Comparison between the triglycerides determination by HPLC in China and reference procedure used in the isotope dilution mass spectrometry CDC CRMLN

Abstract

Objective To evaluate the comparability and consistency of two kinds of triglycerides reference methods, one of which is the isotope dilution liquid chromatography-mass spectrometry (LC/MS) in the Cholesterol Reference Method Laboratory Network (CRMLN), the other isthehigh-performance liquid chromatography (HPLC) method for triglyceride detection in China. Methods 52 fresh frozen sera with triglycerides levels among 0.45-4.52 mmol/L were determined by LC/MS and HPLC. After evaluation the precision and accuracy of the two methods, a series of analyses were conducted including plotting to scatter plots and deviation graphs, testing outliers, selecting the best fitting regression models and calculating the regression equations and parameters, and so on. The expected deviation at the level of medical decision of triglycerides and the 95% confidence range were statistically analyzed. Results For HPLC method, the CV of instrument measurement was 0.29%(0%-1.16%), the total CV of samples measurement was 0.54%(0.04%-1.28%), and the average bias of the reference materials was 0.22% (-0.43%-0.68%). ForLC/MSmethod,the CV of instrument measurement was 0.55%(0%-1.68%), the total CV of samples measurement was 0.79%(0%-1.93%), and the average bias of the NIST reference materials was 0.09%(-0.73%-1.29%). No outlier was found from the scatter plots and the statistical analysis and the linear regression was fitted to analyze the results of the two methods. The linear regression parameters of two methods for 52 fresh frozen human sera were as follows: the slope was 0.998 8, the standard error of slope was 0.003 5, the intercept was 0.003 7mmol/L, the standard error of intercept was 0.003 0 mmol/L, the standard error of Y-estimate was 0.023 6 mmol/L, and the correlation coefficient was 0.999 7. Compared with the LC/MS method, the absolute deviation of fresh sera by HPLC method was -0.001 mmol/L (-0.070-0.056 mmol/L), with a relative deviation of 0.13% (-2.01-2.83%). T-test showed no statistically significant difference between the two methods. The expected deviations at the triglycerides medicine decision level were within the 95% confidence range, and the expected deviations were far less than the allowable error. Conclusions The HPLC method of triglyceridesdetetion has good consistency and comparability with LC/MS method as one of the reference methods of CRMLN. Because of the advantages of HPLC method such as low cost, simplicity, less technical need, and better precision, HPLC method is expected to play an important role in the process of standardization and traceability of serum triglycerides. Key words: Triglycerides; Chromatography, high pressure liquid; Chromatography, liquid; Tandem mass spectrometry; Isotopes