Study On The Quality Assurance Of Determination Of Cadmium In Large Quantities Of Urines Come From Areas Polluted By Environmental Cadmium

[Objectives:] To assure the accuracy of determination of cadmium in large quantity of urine samples come from the areas polluted by cadmium, so as to provide examination datum accorded with quality requirement for the investigation group of the cadmium pollution affair, and at the same time to study a method for the whole quality assurance process of the examination for large quantities biomaterials in collective unexpected public health affairs.[Methods] According to the concrete requests of CNAS' correlative documents such as《Certificated rules for laboratory determination and ajustment》,《Evaluation directory of the uncertainty in chemical analysis》and the quality assurance system of the own laboratory, and combining with the actual situation of this environmental cadmium polluted affair,the quality control and evaluation measures were taken through the whole process of the examination for cadmium in large quantities of urines in the study ,and the meassures included taking standard examination methods, quality controlls in sampling , receiving samples and standard methods itselves. At the same time of founding integrated quality assurance system, the examination's accuracy and repeatability were evaluated by reserving samples for reexamination and determination for quality control samples,and took reliable and reasonable data statistical strategy to insure the accuracy of the examination datas. The validated evaluation for the whole quality of the examination datum was also taken by contrast with the laboratory ability validation, especially the uncertainty analysis of the examination results.[Results] A total of 1639 urine samples were examined in the study and the examined 1324 people were in the investigation area, in which the urine results of 1305 people were effective. The determination of cadmium in urine by atomic absorption spectrometry revised 32 working curves totally, and the correlation coefficient of curves were in the range of 0.9951～0.9998.The determination of urinary creatinine by spectrometry revised 11 standard curves totally whose correlation coefficient were in the range of 0.9993～0.9999. A total of 121 parallel samples were examined in the study, and the relative standard deviation (RSD) of the results was 3.7%. Altogether 43 repetitive samples were examined and the RSD of the results was 3.2%. The results of the reserving samples' reexamination were checked by t test and P=0.200,so there was no significant dififerency between the fore-and-aft results while a=0.05. The extended uncertainty was 0.42μg/g(creatinie) when the result of urinary cadmium was 4.51μg/g(creatinie).The contrastive result between two laboratories was checked by t test and P=0.518, and there was no significant differency between two laboratories' results whileα=0.05.[Conclusions] In the process of the cadmium determination in large quantities of urines, the integrated quality assurance measures were taken, the examination methods and quality controls inside the laboratories and between laboratories are accorded with the request of correlative quality control, and the uncertainty of the examined results can be accepted absolutely by data users and can become the important gist for the estimation of the healthy dangerous area polluted by cadmium. Those quality assurance measures taked in the whole process can provide references for similar studies or determination.