ABSTRACT
Objective To verify a new revised method with low usage amount of arsenic trioxide for determining urinary iodine by As(Ⅲ)-Ce4+ catalytic spectrophotometry using ammonium persulfate digestion.Methods The standard curve linearity,sample detection limit,precision and accuracy of determining urinary iodine of this modified method were verified according to Determination Methods of Chemicals in Biological Materials.Results The linear correlative coefficients of the 0-300 μg/L range and 300-1200 μg/L range calibration curve were-0.9998--1.0000(n =6) and-0.9998--1.0000,respectively.The detection limit for iodine was 1.3 μg/L.The relative standard deviations were 1.5％ (1.1/71.3)-2.5％ (6.2/244.9) when measuring 3 urine samples with iodine concentration of 71.3-244.9 μg/L,and 0.6％(2.4/388.5)-1.7％(17.3/1018.0) when measuring 3 urine samples with iodine concentration of 388.5-1018.0 μg/L,respectively(n =6).The test results of the four urinary iodine national standard materials with iodine concentration of 73.0,206.0,556.0 and 883.0 μg,/L were all within the given value range and the average value relative deviation was 1.8％ (1.3/73.0),0.4％ (0.8/206.0),0.2％ (1.0/556.0) and-1.6％(-13.7/883.0),respectively (n =6).The average recovery was 98.8％ with a range of 93.2％ (186.3/200.0)-103.4％(51.7/50.0) when measuring 3 urine samples with iodine concentration of 64.6-144.9 μg/L and 3 urine samples with iodine concentration of 346.8-574.4 μg/L,respectively.Conclusions This new modified method greatly reduces the amount of waste containing arsenic,and can directly take urine samples with high iodine concentration to digest and determine without dilution.It is performed with good standard linear curve,better precision and high accuracy,and in line with the analysis of biological samples requirements.