基于在盐酸介质中,碘酸钾氧化联苯胺使其显色,提出了光度法测定食盐中微量碘的方法.在40 ℃的水浴中,当2 mol·L-1盐酸溶液用量为1.00 mL、0.42 g·L-1联苯胺溶液用量为0.80 mL时,方法的线性范围为100~1 400 μg·L-1,最大吸收波长在425 nm处,表观摩尔吸光率为1.4×105L·mol-1·cm-1.用于测定加碘食盐中碘含量的测定,回收率在97.5%~101.2%之间,相对标准偏差(n=7)在0.9%~1.9%之间.

Based on the color reaction of potassium iodate with benzidine in HCl medium,a spectrophotometric method for the determination of iodine in table salt was proposed.Linearity range of the method was found between 100-1 400 μg·L-1,at 45 ℃ in a water bath and with addition of 1.00 mL of 2.0 mol·L-1 HCl and 0.80 mL of 0.42 g·L-1 benzidine solution.The absorption maximum was at the wavelength of 425 nm and the apparent molar absorptivity found was 1.4×105L·mol-1 ·cm-1.The proposed method was used in the determination of iodine in table salt,giving the values of recovery and RSD (n=7) in ranges of 97.5%-101.2% and 0.9%-1.9%,respectively.