TY - JOUR
AU - Weiner,, P.H.
AB - Abstract Currently, there are three major methods in use to measure μg/l levels of tri- and tetrahalomethanes in aqueous media, namely, (A) a direct aqueous injection method into a gas chromatograph equipped with a selective detector, (B) a liquid-liquid extraction procedure, and (C) a nonequilibrium headspace analysis or gas sparging procedure. During the past several years the authors have encountered problems in applying either of the latter two methods as they currently appear in the literature to various types of samples. Particularly with the nonequilibrium headspace procedure, problems of severe sample foaming with industrial effluent samples and difficulty in reproducibly calibrating the system were encountered. For the liquid-liquid extraction procedure, problems of severe gas chromatographic detector nonlinearity for samples containing mg/l levels were encountered. Also, the extracting solvents frequently were found to contain the components of interest. In the current paper several modifications are made to both procedures to help eliminate these problems. For the nonequilibrium headspace method these modifications involved a redesign of the sparging apparatus. For the liquid-liquid extraction procedure, a way is suggested to estimate the partition coefficients using the ideas developed by Hansch, so that it is no longer necessary to neglect the equilibrium concentrations of the halogenated methanes in the water phase from the final calculation of the original water concentrations. Therefore, the phase ratios can now be adjusted to ensure that the electron capture detector is operating in its linear range. Experimental partition coefficients of several halogenated methanes are measured and are compared with both the estimated partition coefficients and data in the literature. Finally, samples of river water, drinking water, and a time series experiment of haloform production during chlorination are measured using the two modified procedures, and it is shown that either method can be used to measure μg/l levels of haloforms in water samples. * Presented in part at the Northeastern Regional Chromatography Discussion Group, FMC, Middleport, New York, 1977 This content is only available as a PDF.
TI - Modifications to Methods for Volatile Organics Analysis at Trace Levels
JF - Journal of Chromatographic Science
DO - 10.1093/chromsci/18.7.333
DA - 1980-07-01
UR - https://www.deepdyve.com/lp/oxford-university-press/modifications-to-methods-for-volatile-organics-analysis-at-trace-0ohE4Oy0qH
SP - 333
EP - 342
VL - 18
IS - 7
DP - DeepDyve
ER -