Kawaguchi Migaku, Takatsu Akiko
Bio-Medical Standard Section, National Metrology Institute of Japan, Tsukuba, Ibaraki.
Anal Sci. 2009 Aug;25(8):989-92. doi: 10.2116/analsci.25.989.
A candidate reference measurement procedure involving isotope dilution coupled with gas chromatography-mass spectrometry (GC-MS) has been developed and critically evaluated. An isotopically labeled internal standard, cortisol-d(2), was added to a serum sample. After equilibration, solid-phase extractions (SPE) for sample preparation and derivatization with heptafluorobutyric anhydride (HFBA) were performed for GC-MS analysis. The limit of detection (LOD) and the limit of quantification (LOQ) were 5 and 20 ng g(-1), respectively. The recovery of the added cortisol ranged from 99.8 to 101.0%. Excellent precision was obtained with a within-day variation (RSD) of 0.7% for GC-MS analysis. The accuracy of the measurement was evaluated by comparing of results of this reference measurement procedure on lyophilized human serum reference materials for cortisol (European Reference Materials (ERM)-DA 192) as Certified Reference Materials (CRMs). The results of this method for total cortisol agreed with the certified values within some uncertainty. This method, which demonstrates simply, easy, good accuracy, high precision, and is free from interferences from structural analogues, qualifies as a reference measurement procedure.
一种涉及同位素稀释与气相色谱 - 质谱联用（GC - MS）的候选参考测量程序已被开发并进行了严格评估。将同位素标记的内标物皮质醇 - d(2)添加到血清样本中。平衡后，进行固相萃取（SPE）用于样品制备，并用七氟丁酸酐（HFBA）进行衍生化以用于GC - MS分析。检测限（LOD）和定量限（LOQ）分别为5和20 ng g(-1)。添加的皮质醇回收率在99.8%至101.0%之间。GC - MS分析的日内变异（RSD）为0.7%，获得了极佳的精密度。通过将该参考测量程序对皮质醇冻干人血清参考物质（欧洲参考物质（ERM） - DA 192）作为有证参考物质（CRM）的结果进行比较，评估了测量的准确性。该方法测定总皮质醇的结果在一定不确定度范围内与认定值一致。该方法操作简单、准确度高、精密度高且不受结构类似物干扰，符合参考测量程序的要求。
