Measurement of urinary iodine using ammonium persulfate digestion -As-Ce catalytic spectrophotometry with temperature-controlled oil bath

Objective To determine the precision and accuracy of measurement of urinary iodine levels in urine samples digested by temperature-controlled oil bath. Methods The urinary iodine level in the urine samples, digested by temperature-controlled oil bath instead of electrothermal digestion devices, was determined according to the As-Ce catalytic spectrophotometry method for measurement of urinary iodine (WS/T 107-2006). Results The linear range of the standard curve was 0-300 g/L, the average correlation coefficient -0.9998. In terms of the precision, the coefficients of variation in determining the urinary iodine levels of three samples with the contents of (67.6 10),(110.5 10), (223.4 10)g/L were 3.1%, 2.3%, and 4.7% (n=6), respectively. In terms of the accuracy, the relative standard deviations in determining the levels of two national standard substances of iodine-containing urine samples with the iodine content of (78.4 9) and (150.5 10)g/L were 4.8% and 2.8% (n=6), respectively. Conclusion Temperature-controlled oil bath, featuring precise temperature control and ease of making, is a good substitute for electrothermal devices for the measurement of urinary iodine levels.