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A novel method based on diffused reflectance Fourier-transform infrared spectroscopy (DRS-FTIR) was employed for iodate determination in food grade salt and food products. The method attained sensitivity that was comparable to or better than that in most of the contemporary spectrophotometric methods. This was realized through a combination of azo dye formation and dispersive liquid–liquid microextraction of dye when a 37-fold enrichment was obtained. FT-IR enabled integrating alternative target peak, and freedom in sample solvent composition relative to UV–visible spectrophotometry where the solvent polarity, pH, and presence of ions may affect the spectral properties of the measurable coloured species. Food samples containing iodide or covalently bonded iodine were oxidized with alkaline permanganate for mineralization and iodate formation. Optimization of both reaction conditions was carried out by means of response surface methodology. The method had a linear range 0.04–10 mg kg−1 iodate and limit of detection of 4.4 µg kg−1.

The Berthelot reaction for ammonia is revisited with the aim of miniaturization and addressing interferences as encountered with food and water samples. Headspace single drop microextraction of ammonia in phosphoric acid served to attain selectivity in complex matrices, and liquid-liquid microextraction of red or blue indophenol species into 1-octanol-isooctane (60:40, v/v) resulted into high sensitivity. Fiber-optics-based cuvetteless micro-spectrophotometry has been used for colorimetric determination on microliter volumes of extract. The linear dynamic range, limit of detection and enrichment factor have been found to be 0.2–3 mg kg−1, 0.14 mg kg−1 and 38, respectively, measuring red species for milk, cheese and beer (4.9–5.5% error; 4.8–6.3% RSD; n = 5); and 5–400 µg L−1, 0.4 µg L−1 and 137, respectively, measuring blue species for water samples (3.3–5.7% error; 3.6–6.8% RSD; n = 5). A plausible reaction scheme has been proposed for nitroprusside catalysis in indophenol reaction.

2-Iodosobenzoate and N,N -dimethylaniline have been used at pH 6.4 for selective conversion of iodide to 4-iodo- N,N -dimethylaniline which was extracted with ethanol, when the phase separation occurred by addition of ammonium sulphate, a process called salt-assisted liquid–liquid microextraction (SALLME), and analysed by high-performance liquid chromatography-diode array detection. Iodate was reduced to iodide before derivatisation. The method has been optimised for extracting solvent, salt for phase separation, and reaction time. A linear calibration was obtained for 10 μg-10 mg L −1 of iodide with correlation coefficient of 0.9989 and limit of detection of 3.7 μg L −1 . The SALLME produced 280-fold enrichment of the derivative. The commercial iodised table salt samples have been found highly inhomogeneous; the RSD in analysis of different aliquots of the same sample ranged 18.0-78.1%. The average recovery of spiked iodide to real samples was 98.4% with an average RSD of 7.9% (range 5.2-12.4%).