Clin Chim Acta. 2014 Jan 20;428:20-5.
Triglycerides are widely tested in clinical laboratories using enzymatic methods for lipid profiling. As enzymatic methods can be affected by interferences from biological samples, this together with the non-specific nature of triglycerides measurement makes it necessary to verify the accuracy of the test results with a reference measurement procedure. Several such measurement procedures had been published. These procedures generally involved lengthy and laborious sample preparation steps. In this paper, an improved reference measurement procedure for triglycerides and total glycerides was reported which simplifies the sample preparation steps and greatly shortens the time taken.
The procedure was based on isotope dilution gas chromatography-mass spectrometry (IDGC-MS)with tripalmitin as the calibration standard. Serum samples were first spiked with isotope-labeled tripalmitin. For the measurement of triglycerides, the serum samples were subjected to lipid extraction followed by separation of triglycerides from diglycerides and monoglycerides. Triglycerides were then hydrolyzed to glycerol, derivatized and injected into the GC–MS for quantification. For the measurement of total glycerides, the serum samples were hydrolyzed directly and derivatized before injection into the GC-MS for quantification.
All measurement results showed good precision with CV <1%. A certified reference material (CRM) of lipids in frozen human serum was used to verify the accuracy of the measurement. The obtained values for both triglycerides and total glycerides were well within the certified ranges of the CRM, with deviation <0.4% from the certified values. The relative expanded uncertainties were also comparable with the uncertainties associated with the certified values of the CRM. The validated procedure was used in an External Quality Assessment (EQA) Program organized by our laboratory to establish the assigned values for triglycerides and total glycerides.
临床实验室广泛使用酶法测定甘油三酯来进行血脂分析。由于酶法可能会受到生物样本干扰的影响，再加上甘油三酯测量的非特异性，因此有必要使用参考测量程序来验证检测结果的准确性。已经发表了几种这样的测量程序。这些程序通常涉及冗长而繁琐的样品制备步骤。本文报道了一种改进的甘油三酯和总甘油的参考测量程序，该程序简化了样品制备步骤，大大缩短了所需时间。
该程序基于同位素稀释气相色谱-质谱法（IDGC-MS），以三棕榈酸甘油酯作为校准标准。血清样品首先用同位素标记的三棕榈酸甘油酯进行标记。对于甘油三酯的测量，血清样品进行脂质提取，然后将甘油三酯与二甘油酯和单甘油酯分离。然后将甘油三酯水解为甘油，衍生化后注入 GC-MS 进行定量。对于总甘油的测量，血清样品直接水解后衍生化，然后注入 GC-MS 进行定量。
所有测量结果的精密度均良好，CV<1%。使用冷冻人血清中的脂质认证参考物质（CRM）来验证测量的准确性。获得的甘油三酯和总甘油的测量值均在 CRM 的认证范围内，与 CRM 的认证值的偏差<0.4%。相对扩展不确定度也与 CRM 的认证值相关的不确定度相当。经过验证的程序用于我们实验室组织的外部质量评估（EQA）计划，以确定甘油三酯和总甘油的赋值。
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