Development of Membrane Hollow Fiber for Determination of Maleic Anhydride in Ambient Air as a Field Sampler

Development of Membrane Hollow Fiber for Determination of Maleic Anhydride in Ambient Air as a... Abstract This research develops a rapid method for sampling and analysis of maleic anhydride (MA) in air using a one-step hollow fiber (HF) membrane in the liquid phase followed by high-performance liquid chromatography. A sampling chamber was prepared for sampling of MA with HF-supported de-ionized water absorbency. Several important parameters, such as sampling flow rate, sampling time, and breakthrough volume (BTV), were optimized at different concentrations using a central composite design. The results showed that sampling could be performed at the maximum period of 4 h with a flow rate of 1 mL min–1 for different concentrations (in the range of 0.05–2 mg m–3). The BTV was 240 mL. The relative standard deviations for the repeatability of interday and intraday were 7–10%, 10%, respectively, and the pooled standard deviation was 0.088. The limit of detection and limit of quantitation values were 0.033 and 0.060 mg m–3, respectively. Moreover, our findings revealed that the samples could be stored in sealed HF flexible plastic tubes in a cover at refrigerator temperature (4°C) for up to 7 days. The HF method was compared with method number 3512 National Institute Occupational Safety and Health for determination of MA. There was a good correlation (R2 = 0.99) between the two methods at a concentration of 0.05 to 2 mg m–3 in the laboratory and the average concentration of MA for both methods was 0.11 mg m–3 in the ambient air at an adhesive manufacturer. Our findings indicated that the proposed HF can act as a reliable, rapid, and effective approach for sampling of MA in workplaces. air sampling, hollow fiber, liquid absorbent, maleic anhydride Introduction Maleic anhydride (MA) is a solid white substance with a sharp smell that is commonly used in the production of unsaturated polyester resins and 1,4-butanediol (OSHA, 1990; Minamoto et al., 2002; Atta et al., 2007; Trivedi, 2013). The emission of MA in workplaces can affect the respiratory tract of workers and lead to allergic respiratory reactions. Skin contact with MA can cause severe irritation and skin burns and prolonged exposure may lead to dermatitis (OSHA, 1981; Hathaway et al., 1991; Motolese et al., 1993; Minamoto et al., 2002). The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended a workplace standard of 0.01 mg m–3 for MA as an 8-hour time-weighted average (TWA) (ACGIH, 2018). Personal breathing zone sampling is one of the most common methods for assessing the risk of exposure to airborne chemicals. In this regard, various analytical methods have been proposed for sampling and analysis of MA in air (OSHA, 1981, 1990; NIOSH, 1994; Pfäffli et al., 2002). The National Institute Occupational Safety and Health (NIOSH-3512) has recommended the use of a bubbler (impinger) for sampling MA and analyzing the samples using high-performance liquid chromatography (HPLC) with a UV detector (NIOSH, 1994). The use of sorbent tubes such as XAD-2 and Tenax was also recommended for sampling of MA from air (OSHA, 1981; Pfäffli et al., 2002). Despite all the advantages of such sampling techniques, they have some critical limitations during application. Attaching the bubbler to the worker’s collar for to determine TWA concentrations might interfere with their normal work, and the absorbing liquid used in the bubbler and its trap may enter the sampling personal pump and damage it (Okenfuss and Posner, 1980; learning, 2013; OSHA, 2014). In addition, the glass bubbler is prone to breakage due to the movement of workers. Moreover, in the bubbler method, only a small amount of extraction solvent is injected into the analyzer device thereby the sensitivity of the analysis method is dramatically reduced. For this reason, to overcome these limitations and to increase sensitivity, we investigated the application of HF for sampling of MA from air at laboratory and field scale. The application of HF has previously been demonstrated for the separation and extraction of chemical compounds in water and liquid solutions (Payán et al., 2010; Villar-Navarro et al., 2012; Feng et al., 2013; Jahangiri et al., 2013; Shi et al., 2014; Xu et al., 2015; Ghamari et al., 2016). In our previous research, we investigated the application of HF for sampling of 1,1-dimethylhydrazine from air at laboratory scale (Taheri et al., 2018). However, there is still a vast gap of knowledge in the applicability of HF as a monitoring tool for inhalation exposure assessment studies. This study aimed to evaluate the application of HF filled with de-ionized water as a new technique for sampling of MA in air followed by HPLC analysis. The effect of some parameters including flow rate, sampling time, and analyte concentrations was studied on the HF performance for sampling of MA. To evaluate the application of the proposed HF as a field sampler, it was used for determining the workplace concentrations of MA in adhesive manufacturers. The results of sampling and analysis of the compound of interest with the proposed HF and HPLC method were compared with the NIOSH-3512 method in both laboratory and field. Materials and methods Chemicals and materials Methanol 99.9%, formic acid 98%, MA >99%, and dicyclohexylamine >99% were purchased from Merck (Germany). The de-ionized water was prepared in the laboratory with a TKA ultra-water system (Germany). The Q3/2 Accurel PP polypropylene HF membranes (200 µm wall thickness 600 µm inner diameter 0.2 µm pore size) were obtained from membrana GmbH (Germany). A flexible plastic tube with a 600 µm inner diameter and 700 µm outer diameter was purchased from Pars Equip Co. (Iran) and used as a holder for the HF. To prepare the elution mobile phase, 10 mL of dicyclohexylamine and 10 mL of formic acid were diluted by 100 mL of de-ionized water, and then 10 mL of this solution, plus 250 mL methanol, was diluted with 1 L with de-ionized water. A stock standard solution of MA (1000 µg mL–1) was prepared by dissolving 100 mg of the MA in 100 mL of de-ionized water. Finally, the solution was stored in a refrigerator at 4ºC until it was used. Working solutions were prepared daily by diluting an appropriate amount of the stock solution with de-ionized water. The linearity of the MA analysis was determined through the analysis of samples at 7 points calculating the correlation coefficients of the regression equations of the calibration curves, the calibration curve was obtained at different concentrations from 0.1 to 25 µg mL–1 (0.1, 0.2, 0.4, 1, 5, 10, 25 µg mL–1), analyses were performed in triplicate. Instrumentation The chromatographic analysis was conducted using an HPLC system (Agilent Technologies 1260 infinity, Germany) equipped with a G1314F ultraviolet detector and a deuterium lamp (in the wavelength range 190–600 nm), a G1322A solvent degasser, a G1311C pump with low pressure mixing from four individual solvent channels, and a G1313A autosampler with a sample loop of 20 μL. MA was separated using a C18 column (100 mm × 4.6 mm × 3.5 µm, Agilent Eclipse, USA). The flow rate of the mobile phase was 1.7 mL min–1. The injection volume was 20 μL, and the detector wavelength was set at 254 nm. Personal sampling pumps (SKC 224-30 and 222) were used for sampling of MA with the HF and bubbler according to the NIOSH-3512 method. A syringe pump (Sep-10S) was used for the generation of standard test atmospheres (Fig. 1). A Hamilton syringe (100 µL) was purchased from Agilent Technologies. A thermometer (shda-96) and a digital hygrometer (SUN25-H) were provided from Pars Center (Iran). Moreover, a high volume sampling pump (BioLite SKC) was used to collect the air from the sampling chamber. Figure 1. View largeDownload slide A simple schematic of sampling chamber: (a) high volume vacuum pump (BioLite high-volume sample pump, SKC); (b) Personal sampler pump (model skc224-30); (c) Bubbler; (d) low flow pump (personal sampling pump, model SKC 222-3); (e) hollow fiber with holder; (f) syringe pump and glass syringe; (g) sampling chamber (made of glass like an aquarium); (h) digital hygrometer (model SUN25-H); (i) digital thermometer and thermostat (model shda-96); (j) preheating Chamber; (k) system providence moisture; (l) control valve; (m) heater; (n) inlet air. Figure 1. View largeDownload slide A simple schematic of sampling chamber: (a) high volume vacuum pump (BioLite high-volume sample pump, SKC); (b) Personal sampler pump (model skc224-30); (c) Bubbler; (d) low flow pump (personal sampling pump, model SKC 222-3); (e) hollow fiber with holder; (f) syringe pump and glass syringe; (g) sampling chamber (made of glass like an aquarium); (h) digital hygrometer (model SUN25-H); (i) digital thermometer and thermostat (model shda-96); (j) preheating Chamber; (k) system providence moisture; (l) control valve; (m) heater; (n) inlet air. Pilot study A dynamic standard chamber was used to prepare MA concentrations in the desired range in the chamber (Fig. 1). A high volume vacuum pump was used for providing a constant air stream inside the standard chamber. A calibrated syringe pump was applied to inject the analyte of interest (MA) into the premixing chamber. The MA concentrations in the dynamic chamber were accurately measured in accordance with the NIOSH-3512 method. A light bulb was also used to adjust the sampling temperature inside the chamber. To adjust the humidity, the air was passed through a bubbler before entering the sampling chamber. A digital hygrometer was used to measure the relative humidity, and a digital thermometer was also used to monitor the sampling temperature inside the chamber. Sampling with HF (i) An HF was placed in flexible plastic tube and one end of the HF was heated with a heater to block it. The external diameter of hollow fiber was equal to internal diameter of plastic tube (600 µm). As the hollow fiber completely fills in the plastic tube so the air does not pass between the hollow fiber and the plastic tube (Fig. 2). (ii) 50–100 µL of de-ionized water was injected into the lumen of HF and other end was sealed with a heater. For easiness of air penetration into the lumen, 80% of its capacity was filled with de-ionized water (Taheri et al., 2018). (iii) A personal sampling pump was calibrated and attached to HF with flexible tubing and air passes through shell (surface pores) of HF and penetrates to lumen HF and MA absorbed by de-ionized water (Fig. 2). (iv) In field sampling, the flexible plastic tube (holder) was attached to worker’s collar with a clamp and the pump was connected to worker’s belt. In the laboratory scale, the samples were taken from standard chamber. (v) At the end of the sampling process, one end of HF was cut, and then 20 µL of the sample was injected into the HPLC equipped with a UV detector. (vi) The concentration of MA in air was calculated with the following equation: Figure 2. View largeDownload slide A schematic of the hollow fiber sampler with detail. Figure 2. View largeDownload slide A schematic of the hollow fiber sampler with detail. C=mQ⋅t (1) m=Cxv1000 (2) where C represents the MA concentration in the ambient air (mg m–3), m is the mass of the analyte found in the air sample (µg), Q indicates the flow rate of sampling pump (L min–1), t denotes sampling time (min), CX is the MA concentration from calibration curve (µg mL–1), and v represents the volume of de-ionized water used HF (µL). (vii) To evaluate for breakthrough, two HFs were used in series and the front and back HFs were analyzed to evaluate the BTV (Fig. 2). Optimization of methods To optimize the effect of MA concentration and sampling time, for the flow rate and BTV, the HF performance was investigated at various flow rates (1–5 mL min–1), different concentrations of MA (0.05–2 mg m–3), and various sampling times (1–4 h). The results were investigated using response surface methodology (RSM) with central composite design (CCD; Bezerra et al., 2008; Moghaddam et al., 2010). Design expert, v.6.0 software (State-Ease, Inc., MN, USA) was used to design the experiments. Because the TWA standard for occupational exposure limit (OEL) of MA is 1 mg m–3 (OSHA, 1981, 1990; NIOSH, 1994), concentrations of 0.05 to 2 times higher than the recommended OEL was investigated in chamber. The breakthrough percentages were calculated with the following equation: Bt = bb+f×100 (3) where f and b represent the extracted amounts of MA in the front and back HFs, respectively. To decrease the overall sampling time, the maximum sampling flow rate that did not cause a breakthrough for MA was assessed and considered to be the optimum flow rate for further investigations. In this study, a full factorial design expert was used to determine the optimum conditions and the effect of MA concentrations on liquid absorption at different flow rates over the sampling time. This study was conducted for three levels based on full factorial method and study was conducted as two factors–two factors and 27 runs were done. Response RSM is a set of mathematical and statistical techniques for constructing an empirical model. In this method, the goal was to optimize the response (output variable). This response is affected by several independent variables (input variables). In this method, a set of runs is performed to identify the effect of the input variables on the response (Behera et al., 2018). For this purpose, sampling was conducted with two serial HFs at atmospheric standard chamber under the following conditions: the flow rate range (1–5 mL min–1), concentration range of 0.05–2 mg m–3 MA, and sampling time of 1–4 h. The effect of these variables on the amount of mass extraction of MA was specified and the mass amount of analyte extraction was used as response. Validation of method The validation of the HF method was evaluated for the quantitative analysis of the MA in a sampling chamber under the optimal conditions. The calibration curve of sample concentrations was obtained in the range of 0.1–25 µg mL–1. The repeatability of the proposed HF method was calculated as the relative standard deviation from six measurements with HFs at a constant concentration MA and with flow rate of 1 mL min–1 and the humidity and temperature was set at 50% and 25°C. To determine the accuracy of the HF, side-by-side sampling was conducted with the proposed HF and NIOSH-3512 methods in the concentration range 0.05–2 mg m–3 in the standard chamber, and then the correlation between the two methods was determined. The percent recoveries were calculated by dividing the analyte concentration from the HF sampler by actual concentration in the standard chamber (multiplied by 100). The NIOSH and Occupational Safety and Health Administration (OSHA) use recovery from sampling devices spiked at the limit of detection (LOD) concentrations to establish the LOD, but in current method, to determine the method LOD and limit of quantitation (LOQ), the concentration and sampling time in standard chamber were successively reduced until the HPLC measurements from exposed samplers gave signal-to-noise ratios (S/N) of 3 and 10. In this case, samples obtained from analyte in the air; therefore, it is more close to real conditions than spiked sample. The storage time for the proposed HF as a sampler was investigated at a constant MA concentration of 10 µg mL–1 under optimum conditions. In this step of experiments, storage time was investigated under two different storage conditions: storing in a cover at laboratory temperature (18–23°C), and storage in a cover at refrigeration temperature (4°C). The samples were analyzed from 1 to 7 days, and the peak area response of the MA was compared with the initial analyte concentrations to determine the amount of analyte loss during storage. Field sampling of MA by HF After optimizing the application of the HF for sampling MA in the laboratory scale, eight HFs and eight bubblers were used for field sampling and analyzed within 2 working days (four HFs and four bubblers for each day) in March 2018. The sampling was conducted for 4 h (from 8 am to 12 am). HF filled with de-ionized water was used to determine the concentration of MA workers exposures at an adhesive manufacturing facility. The proposed HF was attached to a calibrated low-volume personal sampling pump with a flow rate of 1 mL min–1 and sampling volume of 240 mL. The proposed sampler was attached to respiratory zone of workers at the adhesive manufacturer to estimate their exposure to MA. Results and discussion Optimization In the use of HF, the BTV and flow rate of air through the HF were investigated. In the HF method, by increasing the length of the hollow fiber and increasing the volume of de-ionized water, the amount of breakthrough will be decreased. The BTV also had an inverse relation with the concentration of MA in the sample and the sampling flow rate. To determine the BTV, two HFs were filled with de-ionized water and connected in series; two HFs using flexible plastic tube were connected to the sampling pump and then two HFs were analyzed using HPLC (Fig. 2). If the mass of analyte found on a backup sampler totals >10% of the mass found on the front sampler breakthrough has occurred and the capacity of the sampler has been exceeded, this criterion was recommended in most of NIOSH methods (NIOSH 1998a,b). The results indicated that the highest concentration of MA was absorbed into absorbing liquid (de-ionized water) of the HF at the flow rate of 1 mL min–1 (Fig. 3). No breakthrough was observed within 240 min of sampling and 240 mL was considered as the BTV for analysis of MA with HF. As shown in Fig. 4, the results of MA analysis at the concentration of 2 mg m–3 showed that the breakthrough occurred at the volumes higher than 240 mL and the data in this figure were obtained by increasing the sampling times, at a constant air flow rate of 1 mL min–1. A good linearity was obtained for the sampling volume profiles before the breakthrough point; after the breakthrough, the linearity of the MA profile was quickly reduced with increasing the sampling volume. Breakthrough may happen due to a lack of sufficient time to dissolve analytes in the solution, especially at higher sampling flow rates. An HF fitting loosely inside a flexible plastic tube (holder) can cause an early breakthrough, which results in a decreased BTV. The reusability of an HF was tested by monitoring the MA residue in the HF after washing with de-ionized water. The analysis of MA residue showed that no analyte was found in the HF after 10 times rinsing with de-ionized water, indicating the reusability of HF. Figure 3. View largeDownload slide Effect of sampling parameters (a: flow rate, b: time) on the mass of amount analyte extraction in the Sampling of maleic anhydride. Figure 3. View largeDownload slide Effect of sampling parameters (a: flow rate, b: time) on the mass of amount analyte extraction in the Sampling of maleic anhydride. Figure 4. View largeDownload slide Sampling volume profile versus extracted amount of maleic anhydride in 0.8 mg m–3 and 2 mg m–3. Figure 4. View largeDownload slide Sampling volume profile versus extracted amount of maleic anhydride in 0.8 mg m–3 and 2 mg m–3. Validity of the method To assess the accuracy of the developed method, side-by-side sampling was conducted using the HF method under optimum conditions and the NIOSH-3512 method in atmospheric standard chamber at concentration range 0.05–2 mg m–3. Samples were taken at 25°C, 50% RH, for 4 h with an air flow rate of 1 mL min–1. As shown in Fig. 5, there was a good agreement between the results obtained with the HF and the NIOSH-3512 method under the laboratory determined conditions. The results showed a strong correlation (R2 = 0.99) between the two methods, and the slope of the regression line was also close to unity, which indicated that the developed HF could be applied as a reliable method for the quantification of MA. Repeatability of the developed method was evaluated by sampling under the same conditions using one HF (sampling time: 4 h, 0.6 mg m–3, n = 6). The precision of interday, intraday, and overall precision for HF sampling method for measuring MA is shown in Table 1 and overall precision for HF sampling method comparison with other sampling methods for measuring MA is shown in Table 2. Relative standard deviations indicated that the developed method has good repeatability. The mean recovery was 98%. To determine the sensitivity of the method, LOD and LOQ parameters were determined for the developed HF method. The results (Table 2) show that the LOD and LOQ parameters were compared with the other methods. The LODs and LOQs for MA sampling with HF compared with the values reported by NIOSH and OSHA (Table 2), indicated that the proposed HF method can detect low concentrations of MA. The HF is an exhaustive method in which amounts of analytes can be absorbed completely until breakthrough occurs. The HF method also uses low volume of absorbing liquid, the HF is a simple method, which can generate an 8-h TWA by sampling in two 4-h periods. In the study of Pfäffli et al. (2002), a Tenax tube with a filter was used to sample MA, and gas chromatography-electron capture detector (GC-ECD) was used to analyze the samples (Pfäffli et al., 2002). The comparison of the performance of the HF and Tenax indicated that both methods have high sensitivity for MA determination in the air. The HF sampler does not require extraction, while in the tenax method, a solvent must be used to extract the analyte. The humidity in the environment may affect the sampler performance. The recovery in the HF method (recovery = 98%) was more than that of Tenax sampler (recovery = 94.4%; Pfäffli et al., 2002) but the value of LOQ in the Tenax sampler was lower than the current method (Table 2). Table 1. Interday, intraday, overall precision (pooled standard deviation) for MA Interday for first day Interday for second day Intraday Overall precision X (Mean, mg m–3) 0.64 0.58 0.61 SD (standard deviation) 0.05 0.06 0.06 RSD (relative standard divisions) (SD/X) 0.07 0.10 0.10 RSD Pooled = pooled standard deviation 0.088 Interday for first day Interday for second day Intraday Overall precision X (Mean, mg m–3) 0.64 0.58 0.61 SD (standard deviation) 0.05 0.06 0.06 RSD (relative standard divisions) (SD/X) 0.07 0.10 0.10 RSD Pooled = pooled standard deviation 0.088 View Large Table 1. Interday, intraday, overall precision (pooled standard deviation) for MA Interday for first day Interday for second day Intraday Overall precision X (Mean, mg m–3) 0.64 0.58 0.61 SD (standard deviation) 0.05 0.06 0.06 RSD (relative standard divisions) (SD/X) 0.07 0.10 0.10 RSD Pooled = pooled standard deviation 0.088 Interday for first day Interday for second day Intraday Overall precision X (Mean, mg m–3) 0.64 0.58 0.61 SD (standard deviation) 0.05 0.06 0.06 RSD (relative standard divisions) (SD/X) 0.07 0.10 0.10 RSD Pooled = pooled standard deviation 0.088 View Large Table 2. Comparison of the current method with other methods in terms of (RSD)a, overall precisionb, (LOD)c, (LOQ)d Method Sampler Analysis RSD (%) Overall precision LOD (mg m–3) LOQ (mg m–3) Current method HF HPLC-UV 7–10 0.088 0.033 0.060 NIOSH-3512 Bubbler HPLC-UV 6.7 0.063 0.041 — OSHA-25 XAD-2 HPLC-UV 7.6 — 0.005 — OSHA-86 Filter coated veratrylamine HPLC-UV 8.86 — 0.033 — Pfaffli pirkko and society Tenax GC-EDC 6.3 — — 0.001 Method Sampler Analysis RSD (%) Overall precision LOD (mg m–3) LOQ (mg m–3) Current method HF HPLC-UV 7–10 0.088 0.033 0.060 NIOSH-3512 Bubbler HPLC-UV 6.7 0.063 0.041 — OSHA-25 XAD-2 HPLC-UV 7.6 — 0.005 — OSHA-86 Filter coated veratrylamine HPLC-UV 8.86 — 0.033 — Pfaffli pirkko and society Tenax GC-EDC 6.3 — — 0.001 aRelative standard deviation (RSD) expresses percentage of repeatability. bOverall precision is defined as the pooled standard deviation for sampling and measurement precision. cThe limit of quantitation (LOQ) based on an estimated signal-to-noise ratios (S/N) of 10. dThe limit of detection (LOD) based on an estimated signal-to-noise ratios (S/N) of 3. View Large Table 2. Comparison of the current method with other methods in terms of (RSD)a, overall precisionb, (LOD)c, (LOQ)d Method Sampler Analysis RSD (%) Overall precision LOD (mg m–3) LOQ (mg m–3) Current method HF HPLC-UV 7–10 0.088 0.033 0.060 NIOSH-3512 Bubbler HPLC-UV 6.7 0.063 0.041 — OSHA-25 XAD-2 HPLC-UV 7.6 — 0.005 — OSHA-86 Filter coated veratrylamine HPLC-UV 8.86 — 0.033 — Pfaffli pirkko and society Tenax GC-EDC 6.3 — — 0.001 Method Sampler Analysis RSD (%) Overall precision LOD (mg m–3) LOQ (mg m–3) Current method HF HPLC-UV 7–10 0.088 0.033 0.060 NIOSH-3512 Bubbler HPLC-UV 6.7 0.063 0.041 — OSHA-25 XAD-2 HPLC-UV 7.6 — 0.005 — OSHA-86 Filter coated veratrylamine HPLC-UV 8.86 — 0.033 — Pfaffli pirkko and society Tenax GC-EDC 6.3 — — 0.001 aRelative standard deviation (RSD) expresses percentage of repeatability. bOverall precision is defined as the pooled standard deviation for sampling and measurement precision. cThe limit of quantitation (LOQ) based on an estimated signal-to-noise ratios (S/N) of 10. dThe limit of detection (LOD) based on an estimated signal-to-noise ratios (S/N) of 3. View Large Figure 5. View largeDownload slide Regression line for measurements with NIOSH-3512 and hollow fiber. Figure 5. View largeDownload slide Regression line for measurements with NIOSH-3512 and hollow fiber. Storage time The storage capability of field sampling is very important whenever the analytical apparatus is not available for on-site analysis. In this case, the samples should be shipped to the laboratory, and it is necessary to determine the storage capability of the sampler for keeping the trapped analytes. For this purpose, in this study, the storage capability of the new produced method was investigated in two different modes, (i) sealed HF flexible plastic tubes in a cover at laboratory temperature (18–23°C) and (ii) sealed HF flexible plastic tubes in a cover at refrigerator temperature (4°C). Samples were taken consecutively with the HF under each of storage conditions. The first was analyzed immediately, and the other samples were analyzed after the storage times. The results showed that, from the third day, the amount of analytes in the samples stored at laboratory temperature decreased by 40%, but the samples stored at refrigerator temperature were stable up to 7 days (Fig. 6). Ambient temperature is the most important parameter as the loss trend for HF method. In the NIOSH-3512 method, samples can be stored up to 7 days (NIOSH, 1994). The proposed HF method in comparison with the NIOSH-3512 method has the same storage capacity. The probability of breakthrough at high sampling times (>4 h) and high concentrations (>2 times the OEL) can be considered as the limitations of HF method. Figure 6. View largeDownload slide Peak area response for analytical performance of hollow fiber for 7 day at two conditions of storage time (Cover, refrigerator temperature and Cover, laboratory temperature). Figure 6. View largeDownload slide Peak area response for analytical performance of hollow fiber for 7 day at two conditions of storage time (Cover, refrigerator temperature and Cover, laboratory temperature). Field sampling of MA in adhesive manufacturer Field sampling with the HF was also performed to evaluate the HF performance as a field sampler. An adhesive manufacturer was chosen as an appropriate workplace to monitor the MA workplace concentrations. Sampling was conducted at two stations in the respiratory zone of the workers with the HF and the NIOSH-3512 methods. Table 3 shows the results of exposure to MA in adhesive manufacturer. The results demonstrated that the HF method had small variations in responses compared to the NIOSH-3512 method and the concentrations of MA in all stations were above those recommended by ACGIH as a threshold limit value of 0.01 mg m–3 (ACGIH, 2018) but were lower than the OEL(1 mg m–3; OSHA, 1981, 1990; NIOSH, 1994). Table 3. The results for exposure to MA in adhesive manufacturer HF method (mg m–3) NIOSH-3512 method (mg m–3) Samples number 0.08 0.07 1 0.10 0.10 2 0.13 0.13 3 0.08 0.07 4 0.17 0.21 5 0.11 0.10 6 0.08 0.10 7 0.13 0.10 8 Mean = 0.11 Mean = 0.11 HF method (mg m–3) NIOSH-3512 method (mg m–3) Samples number 0.08 0.07 1 0.10 0.10 2 0.13 0.13 3 0.08 0.07 4 0.17 0.21 5 0.11 0.10 6 0.08 0.10 7 0.13 0.10 8 Mean = 0.11 Mean = 0.11 View Large Table 3. The results for exposure to MA in adhesive manufacturer HF method (mg m–3) NIOSH-3512 method (mg m–3) Samples number 0.08 0.07 1 0.10 0.10 2 0.13 0.13 3 0.08 0.07 4 0.17 0.21 5 0.11 0.10 6 0.08 0.10 7 0.13 0.10 8 Mean = 0.11 Mean = 0.11 HF method (mg m–3) NIOSH-3512 method (mg m–3) Samples number 0.08 0.07 1 0.10 0.10 2 0.13 0.13 3 0.08 0.07 4 0.17 0.21 5 0.11 0.10 6 0.08 0.10 7 0.13 0.10 8 Mean = 0.11 Mean = 0.11 View Large Conclusion In this research, a new sampling method was presented based on the use of HF filled with de-ionized water for MA sampling. In this study, as a new technique, the values of LOD and LOQ were determined from the air of the atmospheric chamber instead of the spiked sample method, which is closer to the real conditions. Because of the low LOD, the sensitivity of the developed method is high and can be easily attached to the worker’s collar without being considered as a nuisance to their occupational activities; this can be used to determine the average of an 8-h exposure to MA. In the field sampling, the HF was used for the environmental and occupational monitoring of MA in adhesive manufacturers. The results showed a strong correlation between the HF and the NIOSH-3512 methods in both laboratory and field. Funding Funding for this project was provided by Hamadan University of Medical Sciences (grant number 9512107695). Acknowledgments The authors thank Hamadan University of Medical Sciences for funding this study. Conflict of Interest statement The authors declare no conflict of interest relating to the material presented in this Article. Its contents, including any opinions and/or conclusions expressed, are solely those of the authors. References ACGIH . ( 2018 ) TLVs and BEIs, threshold limit values for chemical substances and physical agents and biological exposure indices . Cincinnati, OH : American Conference of Governmental Industrial Hygienists . Google Preview WorldCat COPAC Atta AM , Nassar IF , Bedawy HM . ( 2007 ) Unsaturated polyester resins based on rosin maleic anhydride adduct as corrosion protections of steel . React Funct Polym ; 67 : 617 – 26 . Google Scholar Crossref Search ADS WorldCat Behera SK , Meena H , Chakraborty S , Meikap B . ( 2018 ) Application of response surface methodology (RSM) for optimization of leaching parameters for ash reduction from low-grade coal . Int J Min Sci Technol ; 28 : 621 – 9 . Google Scholar Crossref Search ADS WorldCat Bezerra MA , Santelli RE , Oliveira EP et al. ( 2008 ) Response surface methodology (RSM) as a tool for optimization in analytical chemistry . Talanta ; 76 : 965 – 77 . Google Scholar Crossref Search ADS PubMed WorldCat Feng C , Khulbe K , Matsuura T , Ismail A . ( 2013 ) Recent progresses in polymeric hollow fiber membrane preparation, characterization and applications . Sep Purif Technol ; 111 : 43 – 71 . Google Scholar Crossref Search ADS WorldCat Ghamari F , Bahrami A , Yamini Y et al. ( 2016 ) Development of hollow-fiber liquid-phase microextraction method for determination of urinary trans,trans-muconic acid as a biomarker of benzene exposure . Anal Chem Insights ; 11 : 65 – 71 . Google Scholar Crossref Search ADS PubMed WorldCat Hathaway GJ , Proctor NH , Hughes JP , Fischman ML . ( 1991 ) Chemical hazards of the workplace . Chemical hazards of the workplace. New York: Van Nostrand Reinhold . Google Preview WorldCat COPAC Jahangiri S , Hatami M , Farhadi K , Bahram M . ( 2013 ) Hollow-fiber-based LPME as a reliable sampling method for gas-chromatographic determination of pharmacokinetic parameters of valproic acid in rat plasma . Chromatographia ; 76 : 663 – 9 . Google Scholar Crossref Search ADS WorldCat Learning OH . ( 2013 ) W501-measurment of hazardous substances including risk assessment . Available at http://www.ohlearning.com/Files/Extracted_Files/48/JA25%20v1-0%2013Apr10%20W501%20Answers%20Day%204.doc. Accessed 11 September 2018 . Minamoto K , Nagano M , Yonemitsu K et al. ( 2002 ) Allergic contact dermatitis from unsaturated polyester resin consisting of maleic anhydride, phthalic anhydride, ethylene glycol and dicyclopentadiene . Contact Dermatitis ; 46 : 62 – 3 . Google Scholar Crossref Search ADS PubMed WorldCat Moghaddam SS , Moghaddam MR , Arami M . ( 2010 ) Coagulation/flocculation process for dye removal using sludge from water treatment plant: optimization through response surface methodology . J Hazard Mater ; 175 : 651 – 7 . Google Scholar Crossref Search ADS PubMed WorldCat Motolese A , Truzzi M , Giannini A et al. ( 1993 ) Contact dermatitis and contact sensitization among enamellers and decorators in the ceramics industry . Contact Dermatitis ; 28 : 59 – 62 . Google Scholar Crossref Search ADS PubMed WorldCat NIOSH . ( 1994 ) Manual of Analytical Methods (NMAM), maleic anhydride . In, 4 th edn. Available at https://www.cdc.gov/niosh/docs/2003-154/pdfs/3512.pdf. Accessed 11 September 2018 . Google Preview WorldCat COPAC NIOSH . ( 1998a ) Manual of Analytical Methods (NMAM), benzothiazole in asphaltfume . Available at https://www.cdc.gov/niosh/docs/2003-154/pdfs/2550.pdf. Accessed 28 March 2019 . Google Preview WorldCat COPAC NIOSH . ( 1998b ) Manual of Analytical Methods (NMAM), methylene chloride , Available at https://www.cdc.gov/niosh/docs/2003–154/pdfs/1005.pdf. Accessed 28 March 2019 . Google Preview WorldCat COPAC Okenfuss JR , Posner J . ( 1980 ) Investigation of an air sampling and analytical method for methyl ethyl ketone peroxide. Book Investigation of an air sampling and analytical method for methyl ethyl ketone peroxide, City . Cincinnati, OH (USA) : National Inst. for Occupational Safety and Health . Google Preview WorldCat COPAC OSHA . ( 1981 ) Occupational safety & health administration, chemical sampling information, maleic anhydride . Available at https://www.osha.gov/dts/sltc/methods/organic/org025/org025.html. Accessed 11 September 2018 . Google Preview WorldCat COPAC OSHA . ( 1990 ) Occupational safety & health administration, chemical sampling information, maleic anhydride . Available at https://www.osha.gov/dts/sltc/methods/organic/org086/org086.html. Accessed 11 September 2018. Google Preview WorldCat COPAC OSHA . ( 2014 ) Personal sampling for air contaminants-oregon OSHA . Available at https://osha.oregon.gov/OSHARules/technical-manual/Section2-Chapter1.pdf. Accessed 11 September 2018 . Google Preview WorldCat COPAC Payán MR , López MÁB , Fernández-Torres R , Mochón MC , Ariza JLG . ( 2010 ) Application of hollow fiber-based liquid-phase microextraction (HF-LPME) for the determination of acidic pharmaceuticals in wastewaters . Talanta ; 82 : 854 – 8 . Google Scholar Crossref Search ADS PubMed WorldCat Pfäffli P , Hämeilä M , Kuusimäki L et al. ( 2002 ) Determination of maleic anhydride in occupational atmospheres . J Chromatogr A ; 982 : 261 – 6 . Google Scholar Crossref Search ADS PubMed WorldCat Shi J , Li X , Liu C , Shao M , Zhang H , Zhang H , Yu A , Chen Y . ( 2014 ) Determination of sulfonylurea herbicides in pears using hollow fiber-protected magnetized solvent-bar liquid-phase microextraction HPLC . Chromatographia ; 77 : 1283 – 90 . Google Scholar Crossref Search ADS WorldCat Taheri E , Bahrami A , Shahna FG et al. ( 2018 ) Evaluation of a novel hollow fiber membrane technique for collection of 1,1-dimethylhydrazine in air . Environ Monit Assess ; 190 : 479 . Google Scholar Crossref Search ADS PubMed WorldCat Trivedi B . ( 2013 ) Maleic anhydride . USA: Springer Science & Business Media . Google Preview WorldCat COPAC Villar-Navarro M , Ramos-Payán M , Pérez-Bernal JL et al. ( 2012 ) Application of three phase hollow fiber based liquid phase microextraction (HF-LPME) for the simultaneous HPLC determination of phenol substituting compounds (alkyl-, chloro- and nitrophenols) . Talanta ; 99 : 55 – 61 . Google Scholar Crossref Search ADS PubMed WorldCat Xu B , Chen M , Hou J et al. ( 2015 ) Calibration of pre-equilibrium HF-LPME and its application to the rapid determination of free analytes in biological fluids . J Chromatogr B Analyt Technol Biomed Life Sci ; 980 : 28 – 33 . Google Scholar Crossref Search ADS PubMed WorldCat © The Author(s) 2019. Published by Oxford University Press on behalf of the British Occupational Hygiene Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Annals of Work Exposures and Health (formerly Annals Of Occupational Hygiene) Oxford University Press

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© The Author(s) 2019. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.
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Abstract

Abstract This research develops a rapid method for sampling and analysis of maleic anhydride (MA) in air using a one-step hollow fiber (HF) membrane in the liquid phase followed by high-performance liquid chromatography. A sampling chamber was prepared for sampling of MA with HF-supported de-ionized water absorbency. Several important parameters, such as sampling flow rate, sampling time, and breakthrough volume (BTV), were optimized at different concentrations using a central composite design. The results showed that sampling could be performed at the maximum period of 4 h with a flow rate of 1 mL min–1 for different concentrations (in the range of 0.05–2 mg m–3). The BTV was 240 mL. The relative standard deviations for the repeatability of interday and intraday were 7–10%, 10%, respectively, and the pooled standard deviation was 0.088. The limit of detection and limit of quantitation values were 0.033 and 0.060 mg m–3, respectively. Moreover, our findings revealed that the samples could be stored in sealed HF flexible plastic tubes in a cover at refrigerator temperature (4°C) for up to 7 days. The HF method was compared with method number 3512 National Institute Occupational Safety and Health for determination of MA. There was a good correlation (R2 = 0.99) between the two methods at a concentration of 0.05 to 2 mg m–3 in the laboratory and the average concentration of MA for both methods was 0.11 mg m–3 in the ambient air at an adhesive manufacturer. Our findings indicated that the proposed HF can act as a reliable, rapid, and effective approach for sampling of MA in workplaces. air sampling, hollow fiber, liquid absorbent, maleic anhydride Introduction Maleic anhydride (MA) is a solid white substance with a sharp smell that is commonly used in the production of unsaturated polyester resins and 1,4-butanediol (OSHA, 1990; Minamoto et al., 2002; Atta et al., 2007; Trivedi, 2013). The emission of MA in workplaces can affect the respiratory tract of workers and lead to allergic respiratory reactions. Skin contact with MA can cause severe irritation and skin burns and prolonged exposure may lead to dermatitis (OSHA, 1981; Hathaway et al., 1991; Motolese et al., 1993; Minamoto et al., 2002). The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended a workplace standard of 0.01 mg m–3 for MA as an 8-hour time-weighted average (TWA) (ACGIH, 2018). Personal breathing zone sampling is one of the most common methods for assessing the risk of exposure to airborne chemicals. In this regard, various analytical methods have been proposed for sampling and analysis of MA in air (OSHA, 1981, 1990; NIOSH, 1994; Pfäffli et al., 2002). The National Institute Occupational Safety and Health (NIOSH-3512) has recommended the use of a bubbler (impinger) for sampling MA and analyzing the samples using high-performance liquid chromatography (HPLC) with a UV detector (NIOSH, 1994). The use of sorbent tubes such as XAD-2 and Tenax was also recommended for sampling of MA from air (OSHA, 1981; Pfäffli et al., 2002). Despite all the advantages of such sampling techniques, they have some critical limitations during application. Attaching the bubbler to the worker’s collar for to determine TWA concentrations might interfere with their normal work, and the absorbing liquid used in the bubbler and its trap may enter the sampling personal pump and damage it (Okenfuss and Posner, 1980; learning, 2013; OSHA, 2014). In addition, the glass bubbler is prone to breakage due to the movement of workers. Moreover, in the bubbler method, only a small amount of extraction solvent is injected into the analyzer device thereby the sensitivity of the analysis method is dramatically reduced. For this reason, to overcome these limitations and to increase sensitivity, we investigated the application of HF for sampling of MA from air at laboratory and field scale. The application of HF has previously been demonstrated for the separation and extraction of chemical compounds in water and liquid solutions (Payán et al., 2010; Villar-Navarro et al., 2012; Feng et al., 2013; Jahangiri et al., 2013; Shi et al., 2014; Xu et al., 2015; Ghamari et al., 2016). In our previous research, we investigated the application of HF for sampling of 1,1-dimethylhydrazine from air at laboratory scale (Taheri et al., 2018). However, there is still a vast gap of knowledge in the applicability of HF as a monitoring tool for inhalation exposure assessment studies. This study aimed to evaluate the application of HF filled with de-ionized water as a new technique for sampling of MA in air followed by HPLC analysis. The effect of some parameters including flow rate, sampling time, and analyte concentrations was studied on the HF performance for sampling of MA. To evaluate the application of the proposed HF as a field sampler, it was used for determining the workplace concentrations of MA in adhesive manufacturers. The results of sampling and analysis of the compound of interest with the proposed HF and HPLC method were compared with the NIOSH-3512 method in both laboratory and field. Materials and methods Chemicals and materials Methanol 99.9%, formic acid 98%, MA >99%, and dicyclohexylamine >99% were purchased from Merck (Germany). The de-ionized water was prepared in the laboratory with a TKA ultra-water system (Germany). The Q3/2 Accurel PP polypropylene HF membranes (200 µm wall thickness 600 µm inner diameter 0.2 µm pore size) were obtained from membrana GmbH (Germany). A flexible plastic tube with a 600 µm inner diameter and 700 µm outer diameter was purchased from Pars Equip Co. (Iran) and used as a holder for the HF. To prepare the elution mobile phase, 10 mL of dicyclohexylamine and 10 mL of formic acid were diluted by 100 mL of de-ionized water, and then 10 mL of this solution, plus 250 mL methanol, was diluted with 1 L with de-ionized water. A stock standard solution of MA (1000 µg mL–1) was prepared by dissolving 100 mg of the MA in 100 mL of de-ionized water. Finally, the solution was stored in a refrigerator at 4ºC until it was used. Working solutions were prepared daily by diluting an appropriate amount of the stock solution with de-ionized water. The linearity of the MA analysis was determined through the analysis of samples at 7 points calculating the correlation coefficients of the regression equations of the calibration curves, the calibration curve was obtained at different concentrations from 0.1 to 25 µg mL–1 (0.1, 0.2, 0.4, 1, 5, 10, 25 µg mL–1), analyses were performed in triplicate. Instrumentation The chromatographic analysis was conducted using an HPLC system (Agilent Technologies 1260 infinity, Germany) equipped with a G1314F ultraviolet detector and a deuterium lamp (in the wavelength range 190–600 nm), a G1322A solvent degasser, a G1311C pump with low pressure mixing from four individual solvent channels, and a G1313A autosampler with a sample loop of 20 μL. MA was separated using a C18 column (100 mm × 4.6 mm × 3.5 µm, Agilent Eclipse, USA). The flow rate of the mobile phase was 1.7 mL min–1. The injection volume was 20 μL, and the detector wavelength was set at 254 nm. Personal sampling pumps (SKC 224-30 and 222) were used for sampling of MA with the HF and bubbler according to the NIOSH-3512 method. A syringe pump (Sep-10S) was used for the generation of standard test atmospheres (Fig. 1). A Hamilton syringe (100 µL) was purchased from Agilent Technologies. A thermometer (shda-96) and a digital hygrometer (SUN25-H) were provided from Pars Center (Iran). Moreover, a high volume sampling pump (BioLite SKC) was used to collect the air from the sampling chamber. Figure 1. View largeDownload slide A simple schematic of sampling chamber: (a) high volume vacuum pump (BioLite high-volume sample pump, SKC); (b) Personal sampler pump (model skc224-30); (c) Bubbler; (d) low flow pump (personal sampling pump, model SKC 222-3); (e) hollow fiber with holder; (f) syringe pump and glass syringe; (g) sampling chamber (made of glass like an aquarium); (h) digital hygrometer (model SUN25-H); (i) digital thermometer and thermostat (model shda-96); (j) preheating Chamber; (k) system providence moisture; (l) control valve; (m) heater; (n) inlet air. Figure 1. View largeDownload slide A simple schematic of sampling chamber: (a) high volume vacuum pump (BioLite high-volume sample pump, SKC); (b) Personal sampler pump (model skc224-30); (c) Bubbler; (d) low flow pump (personal sampling pump, model SKC 222-3); (e) hollow fiber with holder; (f) syringe pump and glass syringe; (g) sampling chamber (made of glass like an aquarium); (h) digital hygrometer (model SUN25-H); (i) digital thermometer and thermostat (model shda-96); (j) preheating Chamber; (k) system providence moisture; (l) control valve; (m) heater; (n) inlet air. Pilot study A dynamic standard chamber was used to prepare MA concentrations in the desired range in the chamber (Fig. 1). A high volume vacuum pump was used for providing a constant air stream inside the standard chamber. A calibrated syringe pump was applied to inject the analyte of interest (MA) into the premixing chamber. The MA concentrations in the dynamic chamber were accurately measured in accordance with the NIOSH-3512 method. A light bulb was also used to adjust the sampling temperature inside the chamber. To adjust the humidity, the air was passed through a bubbler before entering the sampling chamber. A digital hygrometer was used to measure the relative humidity, and a digital thermometer was also used to monitor the sampling temperature inside the chamber. Sampling with HF (i) An HF was placed in flexible plastic tube and one end of the HF was heated with a heater to block it. The external diameter of hollow fiber was equal to internal diameter of plastic tube (600 µm). As the hollow fiber completely fills in the plastic tube so the air does not pass between the hollow fiber and the plastic tube (Fig. 2). (ii) 50–100 µL of de-ionized water was injected into the lumen of HF and other end was sealed with a heater. For easiness of air penetration into the lumen, 80% of its capacity was filled with de-ionized water (Taheri et al., 2018). (iii) A personal sampling pump was calibrated and attached to HF with flexible tubing and air passes through shell (surface pores) of HF and penetrates to lumen HF and MA absorbed by de-ionized water (Fig. 2). (iv) In field sampling, the flexible plastic tube (holder) was attached to worker’s collar with a clamp and the pump was connected to worker’s belt. In the laboratory scale, the samples were taken from standard chamber. (v) At the end of the sampling process, one end of HF was cut, and then 20 µL of the sample was injected into the HPLC equipped with a UV detector. (vi) The concentration of MA in air was calculated with the following equation: Figure 2. View largeDownload slide A schematic of the hollow fiber sampler with detail. Figure 2. View largeDownload slide A schematic of the hollow fiber sampler with detail. C=mQ⋅t (1) m=Cxv1000 (2) where C represents the MA concentration in the ambient air (mg m–3), m is the mass of the analyte found in the air sample (µg), Q indicates the flow rate of sampling pump (L min–1), t denotes sampling time (min), CX is the MA concentration from calibration curve (µg mL–1), and v represents the volume of de-ionized water used HF (µL). (vii) To evaluate for breakthrough, two HFs were used in series and the front and back HFs were analyzed to evaluate the BTV (Fig. 2). Optimization of methods To optimize the effect of MA concentration and sampling time, for the flow rate and BTV, the HF performance was investigated at various flow rates (1–5 mL min–1), different concentrations of MA (0.05–2 mg m–3), and various sampling times (1–4 h). The results were investigated using response surface methodology (RSM) with central composite design (CCD; Bezerra et al., 2008; Moghaddam et al., 2010). Design expert, v.6.0 software (State-Ease, Inc., MN, USA) was used to design the experiments. Because the TWA standard for occupational exposure limit (OEL) of MA is 1 mg m–3 (OSHA, 1981, 1990; NIOSH, 1994), concentrations of 0.05 to 2 times higher than the recommended OEL was investigated in chamber. The breakthrough percentages were calculated with the following equation: Bt = bb+f×100 (3) where f and b represent the extracted amounts of MA in the front and back HFs, respectively. To decrease the overall sampling time, the maximum sampling flow rate that did not cause a breakthrough for MA was assessed and considered to be the optimum flow rate for further investigations. In this study, a full factorial design expert was used to determine the optimum conditions and the effect of MA concentrations on liquid absorption at different flow rates over the sampling time. This study was conducted for three levels based on full factorial method and study was conducted as two factors–two factors and 27 runs were done. Response RSM is a set of mathematical and statistical techniques for constructing an empirical model. In this method, the goal was to optimize the response (output variable). This response is affected by several independent variables (input variables). In this method, a set of runs is performed to identify the effect of the input variables on the response (Behera et al., 2018). For this purpose, sampling was conducted with two serial HFs at atmospheric standard chamber under the following conditions: the flow rate range (1–5 mL min–1), concentration range of 0.05–2 mg m–3 MA, and sampling time of 1–4 h. The effect of these variables on the amount of mass extraction of MA was specified and the mass amount of analyte extraction was used as response. Validation of method The validation of the HF method was evaluated for the quantitative analysis of the MA in a sampling chamber under the optimal conditions. The calibration curve of sample concentrations was obtained in the range of 0.1–25 µg mL–1. The repeatability of the proposed HF method was calculated as the relative standard deviation from six measurements with HFs at a constant concentration MA and with flow rate of 1 mL min–1 and the humidity and temperature was set at 50% and 25°C. To determine the accuracy of the HF, side-by-side sampling was conducted with the proposed HF and NIOSH-3512 methods in the concentration range 0.05–2 mg m–3 in the standard chamber, and then the correlation between the two methods was determined. The percent recoveries were calculated by dividing the analyte concentration from the HF sampler by actual concentration in the standard chamber (multiplied by 100). The NIOSH and Occupational Safety and Health Administration (OSHA) use recovery from sampling devices spiked at the limit of detection (LOD) concentrations to establish the LOD, but in current method, to determine the method LOD and limit of quantitation (LOQ), the concentration and sampling time in standard chamber were successively reduced until the HPLC measurements from exposed samplers gave signal-to-noise ratios (S/N) of 3 and 10. In this case, samples obtained from analyte in the air; therefore, it is more close to real conditions than spiked sample. The storage time for the proposed HF as a sampler was investigated at a constant MA concentration of 10 µg mL–1 under optimum conditions. In this step of experiments, storage time was investigated under two different storage conditions: storing in a cover at laboratory temperature (18–23°C), and storage in a cover at refrigeration temperature (4°C). The samples were analyzed from 1 to 7 days, and the peak area response of the MA was compared with the initial analyte concentrations to determine the amount of analyte loss during storage. Field sampling of MA by HF After optimizing the application of the HF for sampling MA in the laboratory scale, eight HFs and eight bubblers were used for field sampling and analyzed within 2 working days (four HFs and four bubblers for each day) in March 2018. The sampling was conducted for 4 h (from 8 am to 12 am). HF filled with de-ionized water was used to determine the concentration of MA workers exposures at an adhesive manufacturing facility. The proposed HF was attached to a calibrated low-volume personal sampling pump with a flow rate of 1 mL min–1 and sampling volume of 240 mL. The proposed sampler was attached to respiratory zone of workers at the adhesive manufacturer to estimate their exposure to MA. Results and discussion Optimization In the use of HF, the BTV and flow rate of air through the HF were investigated. In the HF method, by increasing the length of the hollow fiber and increasing the volume of de-ionized water, the amount of breakthrough will be decreased. The BTV also had an inverse relation with the concentration of MA in the sample and the sampling flow rate. To determine the BTV, two HFs were filled with de-ionized water and connected in series; two HFs using flexible plastic tube were connected to the sampling pump and then two HFs were analyzed using HPLC (Fig. 2). If the mass of analyte found on a backup sampler totals >10% of the mass found on the front sampler breakthrough has occurred and the capacity of the sampler has been exceeded, this criterion was recommended in most of NIOSH methods (NIOSH 1998a,b). The results indicated that the highest concentration of MA was absorbed into absorbing liquid (de-ionized water) of the HF at the flow rate of 1 mL min–1 (Fig. 3). No breakthrough was observed within 240 min of sampling and 240 mL was considered as the BTV for analysis of MA with HF. As shown in Fig. 4, the results of MA analysis at the concentration of 2 mg m–3 showed that the breakthrough occurred at the volumes higher than 240 mL and the data in this figure were obtained by increasing the sampling times, at a constant air flow rate of 1 mL min–1. A good linearity was obtained for the sampling volume profiles before the breakthrough point; after the breakthrough, the linearity of the MA profile was quickly reduced with increasing the sampling volume. Breakthrough may happen due to a lack of sufficient time to dissolve analytes in the solution, especially at higher sampling flow rates. An HF fitting loosely inside a flexible plastic tube (holder) can cause an early breakthrough, which results in a decreased BTV. The reusability of an HF was tested by monitoring the MA residue in the HF after washing with de-ionized water. The analysis of MA residue showed that no analyte was found in the HF after 10 times rinsing with de-ionized water, indicating the reusability of HF. Figure 3. View largeDownload slide Effect of sampling parameters (a: flow rate, b: time) on the mass of amount analyte extraction in the Sampling of maleic anhydride. Figure 3. View largeDownload slide Effect of sampling parameters (a: flow rate, b: time) on the mass of amount analyte extraction in the Sampling of maleic anhydride. Figure 4. View largeDownload slide Sampling volume profile versus extracted amount of maleic anhydride in 0.8 mg m–3 and 2 mg m–3. Figure 4. View largeDownload slide Sampling volume profile versus extracted amount of maleic anhydride in 0.8 mg m–3 and 2 mg m–3. Validity of the method To assess the accuracy of the developed method, side-by-side sampling was conducted using the HF method under optimum conditions and the NIOSH-3512 method in atmospheric standard chamber at concentration range 0.05–2 mg m–3. Samples were taken at 25°C, 50% RH, for 4 h with an air flow rate of 1 mL min–1. As shown in Fig. 5, there was a good agreement between the results obtained with the HF and the NIOSH-3512 method under the laboratory determined conditions. The results showed a strong correlation (R2 = 0.99) between the two methods, and the slope of the regression line was also close to unity, which indicated that the developed HF could be applied as a reliable method for the quantification of MA. Repeatability of the developed method was evaluated by sampling under the same conditions using one HF (sampling time: 4 h, 0.6 mg m–3, n = 6). The precision of interday, intraday, and overall precision for HF sampling method for measuring MA is shown in Table 1 and overall precision for HF sampling method comparison with other sampling methods for measuring MA is shown in Table 2. Relative standard deviations indicated that the developed method has good repeatability. The mean recovery was 98%. To determine the sensitivity of the method, LOD and LOQ parameters were determined for the developed HF method. The results (Table 2) show that the LOD and LOQ parameters were compared with the other methods. The LODs and LOQs for MA sampling with HF compared with the values reported by NIOSH and OSHA (Table 2), indicated that the proposed HF method can detect low concentrations of MA. The HF is an exhaustive method in which amounts of analytes can be absorbed completely until breakthrough occurs. The HF method also uses low volume of absorbing liquid, the HF is a simple method, which can generate an 8-h TWA by sampling in two 4-h periods. In the study of Pfäffli et al. (2002), a Tenax tube with a filter was used to sample MA, and gas chromatography-electron capture detector (GC-ECD) was used to analyze the samples (Pfäffli et al., 2002). The comparison of the performance of the HF and Tenax indicated that both methods have high sensitivity for MA determination in the air. The HF sampler does not require extraction, while in the tenax method, a solvent must be used to extract the analyte. The humidity in the environment may affect the sampler performance. The recovery in the HF method (recovery = 98%) was more than that of Tenax sampler (recovery = 94.4%; Pfäffli et al., 2002) but the value of LOQ in the Tenax sampler was lower than the current method (Table 2). Table 1. Interday, intraday, overall precision (pooled standard deviation) for MA Interday for first day Interday for second day Intraday Overall precision X (Mean, mg m–3) 0.64 0.58 0.61 SD (standard deviation) 0.05 0.06 0.06 RSD (relative standard divisions) (SD/X) 0.07 0.10 0.10 RSD Pooled = pooled standard deviation 0.088 Interday for first day Interday for second day Intraday Overall precision X (Mean, mg m–3) 0.64 0.58 0.61 SD (standard deviation) 0.05 0.06 0.06 RSD (relative standard divisions) (SD/X) 0.07 0.10 0.10 RSD Pooled = pooled standard deviation 0.088 View Large Table 1. Interday, intraday, overall precision (pooled standard deviation) for MA Interday for first day Interday for second day Intraday Overall precision X (Mean, mg m–3) 0.64 0.58 0.61 SD (standard deviation) 0.05 0.06 0.06 RSD (relative standard divisions) (SD/X) 0.07 0.10 0.10 RSD Pooled = pooled standard deviation 0.088 Interday for first day Interday for second day Intraday Overall precision X (Mean, mg m–3) 0.64 0.58 0.61 SD (standard deviation) 0.05 0.06 0.06 RSD (relative standard divisions) (SD/X) 0.07 0.10 0.10 RSD Pooled = pooled standard deviation 0.088 View Large Table 2. Comparison of the current method with other methods in terms of (RSD)a, overall precisionb, (LOD)c, (LOQ)d Method Sampler Analysis RSD (%) Overall precision LOD (mg m–3) LOQ (mg m–3) Current method HF HPLC-UV 7–10 0.088 0.033 0.060 NIOSH-3512 Bubbler HPLC-UV 6.7 0.063 0.041 — OSHA-25 XAD-2 HPLC-UV 7.6 — 0.005 — OSHA-86 Filter coated veratrylamine HPLC-UV 8.86 — 0.033 — Pfaffli pirkko and society Tenax GC-EDC 6.3 — — 0.001 Method Sampler Analysis RSD (%) Overall precision LOD (mg m–3) LOQ (mg m–3) Current method HF HPLC-UV 7–10 0.088 0.033 0.060 NIOSH-3512 Bubbler HPLC-UV 6.7 0.063 0.041 — OSHA-25 XAD-2 HPLC-UV 7.6 — 0.005 — OSHA-86 Filter coated veratrylamine HPLC-UV 8.86 — 0.033 — Pfaffli pirkko and society Tenax GC-EDC 6.3 — — 0.001 aRelative standard deviation (RSD) expresses percentage of repeatability. bOverall precision is defined as the pooled standard deviation for sampling and measurement precision. cThe limit of quantitation (LOQ) based on an estimated signal-to-noise ratios (S/N) of 10. dThe limit of detection (LOD) based on an estimated signal-to-noise ratios (S/N) of 3. View Large Table 2. Comparison of the current method with other methods in terms of (RSD)a, overall precisionb, (LOD)c, (LOQ)d Method Sampler Analysis RSD (%) Overall precision LOD (mg m–3) LOQ (mg m–3) Current method HF HPLC-UV 7–10 0.088 0.033 0.060 NIOSH-3512 Bubbler HPLC-UV 6.7 0.063 0.041 — OSHA-25 XAD-2 HPLC-UV 7.6 — 0.005 — OSHA-86 Filter coated veratrylamine HPLC-UV 8.86 — 0.033 — Pfaffli pirkko and society Tenax GC-EDC 6.3 — — 0.001 Method Sampler Analysis RSD (%) Overall precision LOD (mg m–3) LOQ (mg m–3) Current method HF HPLC-UV 7–10 0.088 0.033 0.060 NIOSH-3512 Bubbler HPLC-UV 6.7 0.063 0.041 — OSHA-25 XAD-2 HPLC-UV 7.6 — 0.005 — OSHA-86 Filter coated veratrylamine HPLC-UV 8.86 — 0.033 — Pfaffli pirkko and society Tenax GC-EDC 6.3 — — 0.001 aRelative standard deviation (RSD) expresses percentage of repeatability. bOverall precision is defined as the pooled standard deviation for sampling and measurement precision. cThe limit of quantitation (LOQ) based on an estimated signal-to-noise ratios (S/N) of 10. dThe limit of detection (LOD) based on an estimated signal-to-noise ratios (S/N) of 3. View Large Figure 5. View largeDownload slide Regression line for measurements with NIOSH-3512 and hollow fiber. Figure 5. View largeDownload slide Regression line for measurements with NIOSH-3512 and hollow fiber. Storage time The storage capability of field sampling is very important whenever the analytical apparatus is not available for on-site analysis. In this case, the samples should be shipped to the laboratory, and it is necessary to determine the storage capability of the sampler for keeping the trapped analytes. For this purpose, in this study, the storage capability of the new produced method was investigated in two different modes, (i) sealed HF flexible plastic tubes in a cover at laboratory temperature (18–23°C) and (ii) sealed HF flexible plastic tubes in a cover at refrigerator temperature (4°C). Samples were taken consecutively with the HF under each of storage conditions. The first was analyzed immediately, and the other samples were analyzed after the storage times. The results showed that, from the third day, the amount of analytes in the samples stored at laboratory temperature decreased by 40%, but the samples stored at refrigerator temperature were stable up to 7 days (Fig. 6). Ambient temperature is the most important parameter as the loss trend for HF method. In the NIOSH-3512 method, samples can be stored up to 7 days (NIOSH, 1994). The proposed HF method in comparison with the NIOSH-3512 method has the same storage capacity. The probability of breakthrough at high sampling times (>4 h) and high concentrations (>2 times the OEL) can be considered as the limitations of HF method. Figure 6. View largeDownload slide Peak area response for analytical performance of hollow fiber for 7 day at two conditions of storage time (Cover, refrigerator temperature and Cover, laboratory temperature). Figure 6. View largeDownload slide Peak area response for analytical performance of hollow fiber for 7 day at two conditions of storage time (Cover, refrigerator temperature and Cover, laboratory temperature). Field sampling of MA in adhesive manufacturer Field sampling with the HF was also performed to evaluate the HF performance as a field sampler. An adhesive manufacturer was chosen as an appropriate workplace to monitor the MA workplace concentrations. Sampling was conducted at two stations in the respiratory zone of the workers with the HF and the NIOSH-3512 methods. Table 3 shows the results of exposure to MA in adhesive manufacturer. The results demonstrated that the HF method had small variations in responses compared to the NIOSH-3512 method and the concentrations of MA in all stations were above those recommended by ACGIH as a threshold limit value of 0.01 mg m–3 (ACGIH, 2018) but were lower than the OEL(1 mg m–3; OSHA, 1981, 1990; NIOSH, 1994). Table 3. The results for exposure to MA in adhesive manufacturer HF method (mg m–3) NIOSH-3512 method (mg m–3) Samples number 0.08 0.07 1 0.10 0.10 2 0.13 0.13 3 0.08 0.07 4 0.17 0.21 5 0.11 0.10 6 0.08 0.10 7 0.13 0.10 8 Mean = 0.11 Mean = 0.11 HF method (mg m–3) NIOSH-3512 method (mg m–3) Samples number 0.08 0.07 1 0.10 0.10 2 0.13 0.13 3 0.08 0.07 4 0.17 0.21 5 0.11 0.10 6 0.08 0.10 7 0.13 0.10 8 Mean = 0.11 Mean = 0.11 View Large Table 3. The results for exposure to MA in adhesive manufacturer HF method (mg m–3) NIOSH-3512 method (mg m–3) Samples number 0.08 0.07 1 0.10 0.10 2 0.13 0.13 3 0.08 0.07 4 0.17 0.21 5 0.11 0.10 6 0.08 0.10 7 0.13 0.10 8 Mean = 0.11 Mean = 0.11 HF method (mg m–3) NIOSH-3512 method (mg m–3) Samples number 0.08 0.07 1 0.10 0.10 2 0.13 0.13 3 0.08 0.07 4 0.17 0.21 5 0.11 0.10 6 0.08 0.10 7 0.13 0.10 8 Mean = 0.11 Mean = 0.11 View Large Conclusion In this research, a new sampling method was presented based on the use of HF filled with de-ionized water for MA sampling. In this study, as a new technique, the values of LOD and LOQ were determined from the air of the atmospheric chamber instead of the spiked sample method, which is closer to the real conditions. Because of the low LOD, the sensitivity of the developed method is high and can be easily attached to the worker’s collar without being considered as a nuisance to their occupational activities; this can be used to determine the average of an 8-h exposure to MA. In the field sampling, the HF was used for the environmental and occupational monitoring of MA in adhesive manufacturers. The results showed a strong correlation between the HF and the NIOSH-3512 methods in both laboratory and field. Funding Funding for this project was provided by Hamadan University of Medical Sciences (grant number 9512107695). Acknowledgments The authors thank Hamadan University of Medical Sciences for funding this study. Conflict of Interest statement The authors declare no conflict of interest relating to the material presented in this Article. Its contents, including any opinions and/or conclusions expressed, are solely those of the authors. References ACGIH . ( 2018 ) TLVs and BEIs, threshold limit values for chemical substances and physical agents and biological exposure indices . Cincinnati, OH : American Conference of Governmental Industrial Hygienists . Google Preview WorldCat COPAC Atta AM , Nassar IF , Bedawy HM . ( 2007 ) Unsaturated polyester resins based on rosin maleic anhydride adduct as corrosion protections of steel . React Funct Polym ; 67 : 617 – 26 . Google Scholar Crossref Search ADS WorldCat Behera SK , Meena H , Chakraborty S , Meikap B . ( 2018 ) Application of response surface methodology (RSM) for optimization of leaching parameters for ash reduction from low-grade coal . Int J Min Sci Technol ; 28 : 621 – 9 . Google Scholar Crossref Search ADS WorldCat Bezerra MA , Santelli RE , Oliveira EP et al. ( 2008 ) Response surface methodology (RSM) as a tool for optimization in analytical chemistry . Talanta ; 76 : 965 – 77 . Google Scholar Crossref Search ADS PubMed WorldCat Feng C , Khulbe K , Matsuura T , Ismail A . ( 2013 ) Recent progresses in polymeric hollow fiber membrane preparation, characterization and applications . Sep Purif Technol ; 111 : 43 – 71 . Google Scholar Crossref Search ADS WorldCat Ghamari F , Bahrami A , Yamini Y et al. ( 2016 ) Development of hollow-fiber liquid-phase microextraction method for determination of urinary trans,trans-muconic acid as a biomarker of benzene exposure . Anal Chem Insights ; 11 : 65 – 71 . Google Scholar Crossref Search ADS PubMed WorldCat Hathaway GJ , Proctor NH , Hughes JP , Fischman ML . ( 1991 ) Chemical hazards of the workplace . Chemical hazards of the workplace. New York: Van Nostrand Reinhold . Google Preview WorldCat COPAC Jahangiri S , Hatami M , Farhadi K , Bahram M . ( 2013 ) Hollow-fiber-based LPME as a reliable sampling method for gas-chromatographic determination of pharmacokinetic parameters of valproic acid in rat plasma . Chromatographia ; 76 : 663 – 9 . Google Scholar Crossref Search ADS WorldCat Learning OH . ( 2013 ) W501-measurment of hazardous substances including risk assessment . Available at http://www.ohlearning.com/Files/Extracted_Files/48/JA25%20v1-0%2013Apr10%20W501%20Answers%20Day%204.doc. Accessed 11 September 2018 . Minamoto K , Nagano M , Yonemitsu K et al. ( 2002 ) Allergic contact dermatitis from unsaturated polyester resin consisting of maleic anhydride, phthalic anhydride, ethylene glycol and dicyclopentadiene . Contact Dermatitis ; 46 : 62 – 3 . Google Scholar Crossref Search ADS PubMed WorldCat Moghaddam SS , Moghaddam MR , Arami M . ( 2010 ) Coagulation/flocculation process for dye removal using sludge from water treatment plant: optimization through response surface methodology . J Hazard Mater ; 175 : 651 – 7 . Google Scholar Crossref Search ADS PubMed WorldCat Motolese A , Truzzi M , Giannini A et al. ( 1993 ) Contact dermatitis and contact sensitization among enamellers and decorators in the ceramics industry . Contact Dermatitis ; 28 : 59 – 62 . Google Scholar Crossref Search ADS PubMed WorldCat NIOSH . ( 1994 ) Manual of Analytical Methods (NMAM), maleic anhydride . In, 4 th edn. Available at https://www.cdc.gov/niosh/docs/2003-154/pdfs/3512.pdf. Accessed 11 September 2018 . Google Preview WorldCat COPAC NIOSH . ( 1998a ) Manual of Analytical Methods (NMAM), benzothiazole in asphaltfume . Available at https://www.cdc.gov/niosh/docs/2003-154/pdfs/2550.pdf. Accessed 28 March 2019 . Google Preview WorldCat COPAC NIOSH . ( 1998b ) Manual of Analytical Methods (NMAM), methylene chloride , Available at https://www.cdc.gov/niosh/docs/2003–154/pdfs/1005.pdf. Accessed 28 March 2019 . Google Preview WorldCat COPAC Okenfuss JR , Posner J . ( 1980 ) Investigation of an air sampling and analytical method for methyl ethyl ketone peroxide. Book Investigation of an air sampling and analytical method for methyl ethyl ketone peroxide, City . Cincinnati, OH (USA) : National Inst. for Occupational Safety and Health . Google Preview WorldCat COPAC OSHA . ( 1981 ) Occupational safety & health administration, chemical sampling information, maleic anhydride . Available at https://www.osha.gov/dts/sltc/methods/organic/org025/org025.html. Accessed 11 September 2018 . Google Preview WorldCat COPAC OSHA . ( 1990 ) Occupational safety & health administration, chemical sampling information, maleic anhydride . Available at https://www.osha.gov/dts/sltc/methods/organic/org086/org086.html. Accessed 11 September 2018. Google Preview WorldCat COPAC OSHA . ( 2014 ) Personal sampling for air contaminants-oregon OSHA . Available at https://osha.oregon.gov/OSHARules/technical-manual/Section2-Chapter1.pdf. Accessed 11 September 2018 . Google Preview WorldCat COPAC Payán MR , López MÁB , Fernández-Torres R , Mochón MC , Ariza JLG . ( 2010 ) Application of hollow fiber-based liquid-phase microextraction (HF-LPME) for the determination of acidic pharmaceuticals in wastewaters . Talanta ; 82 : 854 – 8 . Google Scholar Crossref Search ADS PubMed WorldCat Pfäffli P , Hämeilä M , Kuusimäki L et al. ( 2002 ) Determination of maleic anhydride in occupational atmospheres . J Chromatogr A ; 982 : 261 – 6 . Google Scholar Crossref Search ADS PubMed WorldCat Shi J , Li X , Liu C , Shao M , Zhang H , Zhang H , Yu A , Chen Y . ( 2014 ) Determination of sulfonylurea herbicides in pears using hollow fiber-protected magnetized solvent-bar liquid-phase microextraction HPLC . Chromatographia ; 77 : 1283 – 90 . Google Scholar Crossref Search ADS WorldCat Taheri E , Bahrami A , Shahna FG et al. ( 2018 ) Evaluation of a novel hollow fiber membrane technique for collection of 1,1-dimethylhydrazine in air . Environ Monit Assess ; 190 : 479 . Google Scholar Crossref Search ADS PubMed WorldCat Trivedi B . ( 2013 ) Maleic anhydride . USA: Springer Science & Business Media . Google Preview WorldCat COPAC Villar-Navarro M , Ramos-Payán M , Pérez-Bernal JL et al. ( 2012 ) Application of three phase hollow fiber based liquid phase microextraction (HF-LPME) for the simultaneous HPLC determination of phenol substituting compounds (alkyl-, chloro- and nitrophenols) . Talanta ; 99 : 55 – 61 . Google Scholar Crossref Search ADS PubMed WorldCat Xu B , Chen M , Hou J et al. ( 2015 ) Calibration of pre-equilibrium HF-LPME and its application to the rapid determination of free analytes in biological fluids . J Chromatogr B Analyt Technol Biomed Life Sci ; 980 : 28 – 33 . Google Scholar Crossref Search ADS PubMed WorldCat © The Author(s) 2019. Published by Oxford University Press on behalf of the British Occupational Hygiene Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Journal

Annals of Work Exposures and Health (formerly Annals Of Occupational Hygiene)Oxford University Press

Published: Aug 7, 2019

References

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