Abstract:

Objective To develop the national standard materials of urea,uric acid and total protein in compound frozen human serum,to calibrate and evaluate conventional methods,and to improve the standardization of urea,uric acid and total protein determinations.Methods Serum samples with different levels and without hemolysis,lipemia and choloplania were collected. After filtration and sterilization,serum pools were packed in freezing tubes and stored in -70 ℃. The homogeneity was evaluated by single factor analysis of variance. The stability was evaluated by linear regression analysis. The value was assigned by reference methods or validated method,and the uncertainty was calculated. The commutability of 25 serum samples between reference method and 3 conventional analysis systems was evaluated.Results The F values of homogeneity for urea,uric acid and total protein were 1.071 4,1.339 9 and 1.275 0,respectively. All of them were <F_0.05. The stabilities of urea,uric acid and total protein in candidates can be last at least 37 d at -20 ℃,at least 27,37 and 37 d at 2-8 ℃ and at least 3,8 and 27 d at 20-25 ℃,respectively. The assigned values of candidates for urea,uric acid and total protein were（5.68±0.17） mmol/L（k=2）,（288.68±3.96）μmol/L（k=2）,（67.03±3.46）g/L（k=2）. The linearities for urea,uric acid and total protein for25 samples were all within 95% confidence interval range.Conclusions The homogeneity,stability and commutability of candidates all meet the requirements,and the assigned value is accurate and reliable.

Key words: Urea, Uric acid, Total protein, Frozen human serum, National standard material