A method for determination of urinary iodine by ammonium persulfate digestion-flow injection catalytic spectrophotometry with no needs of highly toxic arsenic reagent / 中华地方病学杂志

ABSTRACT

Objective To establish a catalytic spectrophotometric method for determination of iodine in urine without the use of highly toxic arsenic reagents and with good precision and accuracy. Methods Combined flow injection analysis (FIA) with new catalytic spectrophotometry, a new method for determination of iodine with no need of arsenic reagents was developed by the author. An ammonium persulfate digestion-flow injection catalytic spectrophotometry for determination of iodine in urine was established. Standard serial solutions and urine samples were all digested by ammonium persulfate before testing. The standard curve linearity in the range of 0-1200μg/L, detection limit,precision and accuracy in determining urinary iodine were tested. Results A good calibration relation of C=aA2+bA+d (Ciodine concentration,Ameasuring absorbance peak area from FIA) of the newly developed method existed in the range of 0 - 1200 μg/L. The linear correlative coefficient was 0.9998. The FIA analysis speed was 60 samples per hour. The detection limit for urinary iodine was 7.1μg/L. PrecisionThe intra-assay coefficients of variation (CV) were 0.3％ - 3.0％ (n = 6) when measuring 9 urine samples with iodine concentration of 61.8-806.8μg/L;the intra-assay CV were 0.2％-1.7％(n=6) when measuring 5 urinary iodine national standard materials with iodine concentration of 76.9 - 883.0 μg/L; the inter-assay CV were 1.0％ - 1.2％ when measuring 6 batches of 3 urinary iodine national standard materials with iodine concentration of 76.9 - 232.0 μg/L. AccuracyThe average recovery rate was 98.3％ with a range of 91.2％ - 104.6％ when measuring 20 urine samples with iodine concentration ranged from 18.9 to 807.1 μg/L. The test results of 5 urinary iodine national standard materials were all within the given value range and the relative deviations ranges were-2.9％-0.7％. No significant difference was found between the results of the 48 urine samples determined by the current standard method (WS/T 107.1-2016) and the new method (t=0.029, P>0.05). Conclusions The new method has a wide standard curve range, high sensitivity, good precision and accuracy, and is simple and easy to operate, with automatic sampling, rapid analysis, and no need for toxic arsenic reagent which is difficult to obtain and can pollute the environment. The method is suitable for widely application and can be used as a reliable technical method for urinary iodine detection.