Exploitation of Oxidative Coupling Reaction in Spectrophotometric Determination of Iodate in Iodized Salt

Research Article

Austin J Anal Pharm Chem. 2018; 5(2): 1100.

Exploitation of Oxidative Coupling Reaction in Spectrophotometric Determination of Iodate in Iodized Salt

Al-Okab RA*, Abdul Galil MS

¹Chemistry Department, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen

*Corresponding author: Riyad Ahmed Al-Okab, Chemistry Department, Faculty of Applied Science, Taiz University, Taiz, Republic of Yemen

Received: June 09, 2018; Accepted: July 06, 2018; Published: July 13, 2018

Abstract

A simple and sensitive spectrophotometric method has been described for the determination of iodate. The method was based on the oxidation of Procainamide in hydrochloric acid medium and coupling with phenoxazine (PNZ), which can be spectrophotometrically monitored at 520nm, and the absorbance is directly related to the concentration of iodate in the sample. The calibration curve is linear in the range of 0.08 – 1.13 μg ml-1. The reaction conditions and other important analytical parameters were optimized to enhance the sensitivity of the method. Interference if any, by non-target ions was also investigated. The method was applied successfully for determining iodate in iodized salt with high percentage of recovery, good accuracy and precision.

Introduction

Iodate is not a natural component of water but maybe formed during ozonization (disinfection) of raw water which may contain iodide ions (brackish water and to a lesser extent, in freshwater) [1,2].

Iodine appears to be a trace element essential to animal and plants. Iodine occurs naturally not only as iodide but also as iodate in the form of minerals such as

lautarite [Ca(IO3)2] and dietzeite 7[Ca(IO3)2]8CaCrO4 [3].

Iodine is an essential trace element for human nutrition. The safe dietary intake of iodine as recommended by the World Health Organization (WHO) is 100μg day-1 for infants and 150μg day-1 for adults [4].

There are various analytical methods for determination of iodate in seawater and iodized salt samples [4,5]. Some of the recent methods include spectrophotometry [6,7], spectrofluorometry [8], chemiluminescence [9], colorimetry [10], ion chromatography [11,12], gas chromatography-mass spectrometry [13], transient isotachophoresis- capillary zone electrophoresis [14,15], and electroanalytical methods [16,17], have been reported for the determination of iodate and only a few of them accompanied with a sample preparation step [18].

Most of the techniques are complex and involve sophisticated instruments and complex procedures. It is also observed that application of these analytical methods for iodate determination in table salt is complicated due to the presence of huge excess of chloride [4].

Hence, the aim of the present study is to develop a rapid, reliable and precise, an accurate method for the determination of iodate in table salt, which is based on oxidation of Procainamide in hydrochloric acid medium followed by coupling with phenoxazine (PNZ) in presence of iodate to form red color chromogen, detectable in visible spectroscopic, 520nm (Figure 1).