Institute of Clinical Chemistry, Hospital of the University of Munich, Munich, Germany.
Clin Chem Lab Med. 2010 Nov;48(11):1647-50. doi: 10.1515/CCLM.2010.310. Epub 2010 Aug 13.
The goal of this study was to develop and to validate an improved isotope-dilution-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of methylmalonic acid (MMA) in urine.
A previously described sample preparation protocol requires two solvent extraction steps, including evaporation. The first extraction is to extract the analyte from the sample, and second occurs following derivatization of the extract. In the method described here, the second evaporation step was substituted by on-line solid phase extraction employing column-switching and a permanent co-polymer based extraction cartridge. A standard validation protocol was applied to investigate the performance of the method.
The method was found to be linear in the clinically relevant range of concentrations (6-100 μmol/L). Total coefficients of variation were below 10% and inaccuracy was <10% for quality control samples at three concentrations.
By omitting one evaporation step, the semi-automated method described in this article enables for more convenient work-flow in the quantification of urinary MMA compared to the previous protocol. This is of relevance for MMA measurement in the routine clinical laboratory setting. Validation demonstrated acceptable analytical performance.
本研究旨在开发和验证一种改良的同位素稀释液相色谱-串联质谱（LC-MS/MS）方法，用于定量检测尿液中的甲基丙二酸（MMA）。
先前描述的样品制备方案需要两步溶剂萃取，包括蒸发。第一步萃取是从样品中提取分析物，第二步萃取发生在提取物衍生化之后。在本文描述的方法中，第二个蒸发步骤被在线固相萃取取代，采用柱切换和基于永久共聚物的萃取柱。应用标准验证方案来评估方法的性能。
该方法在临床相关浓度范围内（6-100 μmol/L）呈线性。在三个浓度的质控样品中，总变异系数低于 10%，准确度<10%。
通过省略一个蒸发步骤，与先前的方案相比，本文描述的半自动化方法使得在定量检测尿液 MMA 时具有更方便的工作流程。这对于 MMA 在常规临床实验室检测中具有重要意义。验证结果表明该方法具有良好的分析性能。
