Application of nanostructure ZnLI
complex in construction
of optical pH sensor
Seyed Alireza Shahamirifard | Mehrorang Ghaedi | Morteza Montazerozohori
Chemistry Department, Yasouj University,
Yasouj 75918‐74831, Iran
Mehrorang Ghaedi, Chemistry
Department, Yasouj University, Yasouj
This is for the first time that application of complex nanostructure is reported as
pH indicator in PVC matrix. This new optical pH sensor was constructed
based on incorporation of ZnLI
complex nanostructure in PVC matrix. The
synthesized nanostructure ZnLI
complex was characterized by SEM and
XRD technique. The membrane solution was speared on the glass plate to
provide thin film and the membrane surface morphology was investigated via
field emission scanning microscope (FE‐SEM) technique. Central composite
design (CCD) combined with desirability function (DF) was applied to
find the best experimental composition of membrane providing the highest
absorbance. These conditions were found in correspondence with 3 mg of pH
indicator, 3 mg of ionic additive and 1.5 mg/mg of DBP/PVC weight ratio.
Under optimum conditions, the proposed pH sensor has two linear working
ranges of 4 ‐ 8 at 393 nm (R
= 0.9897) and 5 ‐ 8(R
= 0.9982) at 570 nm with
response time of 4 min. The pK
of proposed pH optical sensor was calculated
through three methods that found to be 5.63. The present optical sensor shows
stability after 2 months without any significant divergence in response properties
(less than 5% RSD). Furthermore, current pH optode was exhibited good repeat-
ability (RSD = 1.14%) as well as reproducibility (RSD = 4.06%). No significant
variation was observed on sensor response with increasing the ionic strength
in the range of 0.0–0.5 M of sodium chloride. All above features indicated that
the proposed sensor can be successfully used for detection of pH in solutions with
different ionic strength.
central composite design nanostructure ZnLI
complex, optical pH sensor
1 | INTRODUCTION
Optical chemical sensors (optodes) are devices with differ-
ent abilities in various fields and technical applications such
as quality and process control, imaging and remote sensing.
Many types of optical chemical sensors were reported which
operated based on absorbance, florescence or luminescence.
In these optodes, indicator molecules due to changing
analyte concentration product a signal proportional with
analyte amount, accordingly detection and determination
of different molecules as well as ions.
Among all sensors, pH sensors have received high
interest because of the significance pH detection in
several scientific research and practical applications.
Therefore proton monitoring under taken by various
techniques like pH test paper strips, electrochemical and
photochemical sensors can usually give a relatively satis-
factory results in aqueous media.
Received: 18 July 2017 Revised: 18 September 2017 Accepted: 23 September 2017
Appl Organometal Chem. 2018;32:e4143.
Copyright © 2017 John Wiley & Sons, Ltd.wileyonlinelibrary.com/journal/aoc 1of11