Spectrophotometric Determination Of Iodide Research Articles

Catalytic spectrophotometric determination of iodide in pharmaceutical preparations and edible salt

The catalytic effect of iodide on the oxidation of four dyes: viz. variamine blue (VB), methylene blue (MB), rhodamine B (RB), and malachite green (MG) with different oxidizing agents was investigated for the kinetic spectrophotometric determination of iodide. The above catalyzed reactions were monitored spectrophotometrically by following the change in dye absorbances at 544, 558, 660, or 617 nm for the VB, RB, MB, or MG catalyzed reactions, respectively. Under optimum conditions, iodide can be determined within the concentration levels 0.064-1.27 µg mL(-1) for VB method, 3.20-9.54 µg mL(-1) for RB method, 5.00-19.00 µg mL(-1) for the MB method, and 6.4-19.0 µg mL(-1) for the MG one, with detection limit reaching 0.004 µg mL(-1) iodide. The reported methods were highly sensitive, selective, and free from most interference. Applying the proposed procedures, trace amounts of iodide in pharmaceutical and edible salt samples were successfully determined without separation or pretreatment steps.

Flow Injection Spectrophotometric Determination of Iodide in Environmental Samples

An alternative and simple flow injection spectrophotometric analysis method for the determination of iodide in environmental samples is reported. The method is based on the catalytic destruction of the colour of the Fe(III)–SCN−–CP+–nBPy quarternary complex. The complex shows maximum absorption at 495 nm. The apparent molar absorptivity of the complex in terms of iodide is (6.22) × 105 l mol−1 cm−1. The detection limit of the method is 0.1 ng ml−1 of iodide. The method obeys Beer’s law up to 120 µg l−1 with slope, intercept and correlation coefficient of 0.11, − 0.52 and + 0.99, respectively. Various flow injection analysis parameters for the determination of iodide in the environmental samples were optimized. The sample throughput of the method is 60 samples h−1. The method was successfully useful for the determination of trace level of iodide in environmental samples i.e. ground, surface water.

Spectrophotometric determination of iodide at the 10–6mol l–1level by solvent extraction with methylene blue

Iodide is separated from other chemical species by its oxidation and subsequent extraction into carbon tetrachloride. The proposed method is based on the extraction of the back-extracted iodide into 1,2-dichloroethane as an ion pair with methylene blue. When a 40-ml sample solution is used, the apparent molar absorptivity for iodide is 3.15 × 105 l mol–1 cm–1 and the Sandell sensitivity for a 0.001 absorbance is 4.3 × 10–4µg cm–2 of l– at 657 nm. A linear calibration graph is obtained over the range 7.5 × 10–8–3 × 10–6M iodide and the relative standard deviation is 0.87% at the 1.5 × 10–6M iodide level. The proposed method was successfully applied to the determination of various amounts of iodide in natural water samples.

Spectrophotometric determination of iodide and iodine at parts-per-million level as a thiocyanate complex

A simple method is described for the determination of iodide or iodine in aqueous solutions by the generation and photometric measurement of an iodine thiocyanate complex, I(SCN)$sub 2$$sup -$, in the presence of excess hydrogen peroxide. Because other halides do not produce serious interferences when present in excesses of several thousandfold, separation from these anions can be avoided in many natural samples. The transition metal ions interfered to varying extents. It is suggested that pretreatment of natural samples with a cation exchange resin could remove interfering cations to acceptable levels. (JGB)