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Objective To carry out a methodological validation of a new standard method "Determination of Iodine in Serum-As3+-Ce4+ Catalytic Spectrophotometry".Methods In accordance with the requirements of "Guide for Establishing Occupational Health Standards-Part 5:Determination Methods of Chemicals in Biological Materials (GB/T 210.5-2008)",the methodological validation was tested in 3 standard development and 3 verification laboratories,calculated the linear relation and range of standard curve and the lowest linmit of detection,precision,accuracy and anti-interference ability,sample stability of sample determination.Results The linear range of iodine mass concentration of the standard curve was 0 to 300 μg/L in 6 laboratories.The linear correlation coefficients of the standard curve obtained from each laboratory were 0.999 1 to 1.000 0.The detection limits of serum iodine were 1.8 to 6.9 μg/L (the.sample amount was 0.10 ml) in 5 laboratories.Precision:15 different serum samples from 5 laboratories with a total iodine concentration range of 48.8 to 273.2 μg/L were repeatedly tested for six times,the relative standard deviations (RSD) were 0.7％ to 3.8％ (the average was 1.7％).Accuracy:a total recovery of samples with iodine concentrations ranging from 26.3 to 253.3 μg/L were performed in 5 laboratories,the recoveries were 96.2％ to 105.2％ (the average was 99.8％).One laboratory carried out the standard method and the inductively coupled plasma mass spectrometry (ICP-MS) method for serum iodine determination.The recovery rates of the two methods were 96.4％ ～ 107.8％,which met the measurement requirements.Anti-interference:15 kinds of chemical reagents were added for interference test in 3 laboratories,and the results showed no deviation,indicating that the standard method had strong anti-interference.Stability:The samples could be stored for 7 days at room temperature,for 2 months at 4 ℃,and for 3 months after freezing when the assay results were not affected.Reaction temperature and time:the appropriate pairing budget for temperature and time was consistent with the standard method.Conclusion The verification of the standard method for serum iodine determination further proves that the standard method has the advantages of simple reagents preparation,wide linear range,better correlation coefficient,lower detection limit,higher precision and accuracy,stronger antiinterference ability,convenient batch testing,and wide applicability.
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Objective To resolve the problem that qualified chloramine T was difficult to purchase for some basic laboratories Methods Using the solution of available chlorine prepared by bleaching power instead of chloramine T, the method for determination of cyanide in drinking water was improved Results The data obtained by this assay accorded with Beers Law in the range of 0～2 0 ?g/25 ml cyanide The detection limit,relative standard deviation,and recovery rate were 0 04?g,2 69%～3 09% and 97 50%～99 17% respectively Conclusion This method for determination of cyanide in drinking water was simple and easy to operate and presented good precision and accuracy
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coarse polished rice for lead respectively. Positive correlations were observed in contents of cadmium and lead between soil and rice (r=0.942～0.994, P