摘要
For determination of iodine,dissolution or oxidation of an organic matrix by acid K-chlorate in dilute nitric acid to obtain non-volatile iodate immediately,is a method of choice.Optical emission spectroscopy is usually sensitive enough to control iodized table salt.Spectral interference by P upon the most sensitive I-emission line,e.g.in mineral feeds and marine algae,was overcome by co-precipitation of P with Al-or Fe hydroxide,leaving iodate(and also borate)in solution.After addition of Al or Fe nitrate or sulfate,ammonia was added to reach pH 8.8,and the resulting precipitate separated by cetrifugation and decantation.Al-hydroxide was more efficient,and its precipitation was facilitated by adding 10-30 mg of a natural clay to 5 mL sample.Correct results with materials from former ring tests were obtained down to 15 mg/kg by an ICP 20 years of age.Highlights:This method enables to use optical emission ICP for determination of high levels of iodine after a simple separation of phosphate from oxidizing acid digests,thus avoiding catalytic or spectrophotometric methods,or high blanks in an ICP-MS utilized for ambient iodine levels.
