Sample preparation for iodine measurement by arsenic cerium catalytic spectrophotometry

Abstract

Objective To screen the suitable sample digestion method for measuring iodine in serum by arsenic cerium catalytic spectrophotometric method, and to carry out the methodology test for the newly developed arsenic cerium catalytic spectrophotometry for determination of iodine in serum. Methods Methodology evaluation. Experimentswere on the sample on the sample digestion method of serum iodine with several common digestive agents. After digestion treatment, the concentration of iodine in serum was determined by arsenic cerium catalytic spectrophotometry. The linearity and linear range of the standard curve, detection limit, precision, recovery rate and anti-interference ability of the newlydeveloped arsenic cerium catalytic spectrophotometry were tested. Results Sample pretreatment method included in the newly developed arsenic cerium catalytic spectrophotometry was selected as follows: perchloric acid-sodium chlorate solution was used as the digestive agent to digest 120 min at 130℃. The calibration relation of C=a+ blgA(C: iodine concentration, A: measuring absorbance) of the newly developed method existed when arsenic ceriumcatalytic reaction was kept at a certain stable temperature range from 13℃ to 30℃ and in certain stable reacting time. The linear range of the calibration curvewas 0 -300 μg/Land the linear correlative coefficient was -0.9996--0.9999. The intra assay coefficients of variation(CVs ) were 0.70%, 0.70% and 0.74% (n=6), and the inter assay CVs were 0.57%, 0.51% and 0.57% (n=6) for 3 serum samples. The average recovery was 97.9% with a range from 92.3% to 105.8% for 3 serum samples. Conclusions The newly developed arsenic cerium catalytic spectrophotometry has good precision and accuracy. The sample digestion agent is easy to be prepared and reserved, and the instrument is simple and easy to be operated. The method can be widely used as a reliable technique for measuring iodine in serum.(Chin J Lab Med, 2017, 40: 119-125) Key words: Iodine; Serum; Reference standards; Spectrophotometry; Arsenicals; Cerium