ABSTRACT
Objective:To establish a method for determination of iodine in salt by arsenic-cerium catalytic spectrophotometry.Methods:The content of iodine in salt was detected by arsenic-cerium catalytic spectrophotometry with an automatic iodine analyzer. The standard curve linearity, detection limit, precision and accuracy of the method were evaluated. The iodine content of 20 edible salt samples was detected by the newly established method and direct titration, and the results were compared.Results:In the range of 0 - 150 μg/L standard curve, the correlation coefficient ( r) = - 0.999 9, and the detection limit was 1.4 mg/kg. The average iodine contents of iodine composition analysis standard materials GBW10006z and GBW10007z were 12.2 and 22.8 mg/kg ( n = 6), respectively, which were all within the given standard value ranges, and the relative standard deviations ( RSD) were 2.04% and 2.33%, respectively. Iodine composition analysis standard materials GBW10006b, GBW10007b, GBW10006v, GBW10007v, GBW10006z and GBW10007z measurement results (12.0, 24.6, 12.6, 22.8, 12.3, 23.2 mg/kg, n = 2) were all within the given standard value ranges, with good quality control. The iodine content of 20 edible salt samples was detected by arsenic-cerium catalytic spectrophotometry and direct titration, respectively, and the difference was not statistically significant ( t = 1.99, P = 0.060). Conclusion:Arsenic-cerium catalytic spectrophotometry has the characteristics of good linear relationship, low detection limit, good precision and high accuracy in determination of salt iodine content, which is suitable for popularization and application.
ABSTRACT
Objective To establish a method for quantitative detection of urine iodine by catalytic spectrophotometry using discrete chemical analyzer.Methods After digestion of urine samples,discrete chemical analyzer was used to control the reaction temperature and time,determine the iodine content,which replaced the urine iodine arsenic cerium catalytic spectrophotometry (standard method) after sample digestion in the testing process,and the linear range,detection limit,precision and accuracy of the method were tested.The method was used to detect the urine iodine and the results were compared with the standard method.Results The urinary iodine was in a linear range of 0-1 000 μg/L,correlation coefficient r =-0.999 7.The detection limit of the method was 4.5 μg/L.Precision:the relative standard deviation (RSD) of urine iodine samples with high,medium,and low concentrations were all ＜ 5％.Accuracy:the contents of urinary iodine in reference materials at high,medium,and low concentrations were within their respective given value ranges.No statistical significant was found in the urinary iodine content detected either by this method or the standard method (t =0.643 8,P ＞ 0.05).Conclusion Catalytic spectrophotometry using discrete chemical analyzer is succeessfully established,this method is simple,rapid,accurate and easy to operate.