Abstract:Abstract:Objectives?To investigate the application potentiality of liquid chromatography tandem mass spectrometry(LC-MS/MS)on establishing target value of apolipoprotein E(apoE)in external quality assessment scheme.Methods?Five pooled human samples were distributed to 76 clinical laboratories by cold-chain for single measurement with immunoturbidimetric assay(ITA).The samples underwent denaturing, alkylation and trypsin digestion with addition of internal standards of isotope labeling arginine.SB-C18 column was used for liquid chromatographic separation, and positive ion mode and multiple reactions monitoring of mass spectrometry were employed for quantification and phenotyping.JMP 13.0 software was used for relative bias analysis among various assay groups.Results?For all samples, the impression of apoE levels within assay measured by ITA varied with assay manufacturers, ranging from 1.7% to 20.4%.The assay?CVs were around 8%(sB-sE spesimen).The mean relative biases of the 5 pooled samples between the results of ITA and LC-MS/MS were-34.2%,-9.4%,-9.8%,-2.7% and-2.1% in the order from low to high levels of samples.The samples with high concentrations were closer to target values than the samples with low concentrations.Conclusion?LC-MS/MS could show the potential on assessing the accuracy of ITA, which may promote its clinical application.