When hospitalized, infants, particularly preterm, are often subjected to multiple painful needle procedures to collect sufficient blood for metabolic screening or diagnostic purposes using standard clinical tests. For example, at least 100 µL of whole blood is required to perform one creatinine plasma measurement with enzymatic colorimetric assays. As capillary electrophoresis–mass spectrometry (CE–MS) utilizing a sheathless porous tip interface only requires limited amounts of sample for in‐depth metabolic profiling studies, the aim of this work was to assess the utility of this method for the determination of creatinine in low amounts of plasma using residual blood samples from adults and infants. By using a starting amount of 5 µL of plasma and an injection volume of only 6.7 nL, a detection limit (S/N = 3) of 30 nM could be obtained for creatinine, and intra‐ and interday precisions (for peak area ratios) were below 3.2%. To shorten the electrophoretic separation time, a multi‐segment injection (MSI) strategy was employed to analyze up to seven samples in one electrophoretic run. The findings obtained by CE–MS for creatinine in pretreated plasma were compared with the values acquired by an enzymatic colorimetric assay typically used in clinical laboratories for this purpose. The comparison revealed that CE–MS could be used in a reliable way for the determination of creatinine in residual plasma samples from infants and adults. Nevertheless, to underscore the clinical efficacy of this method, a subsequent investigation employing an expanded pool of plasma samples is imperative. This will not only enhance the method's diagnostic utility but also contribute to minimizing both the amount and frequency of blood collection required for diagnostic purposes.

中文翻译：

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毛细管电泳-质谱法分析残留临床血浆样本中的肌酐并与金标准测定进行比较

住院时，婴儿，特别是早产儿，经常要接受多次痛苦的针刺手术，以收集足够的血液，用于使用标准临床测试进行代谢筛查或诊断目的。例如，使用酶比色测定进行一次肌酸酐血浆测量至少需要 100 µL 全血。由于利用无鞘多孔尖端接口的毛细管电泳-质谱（CE-MS）仅需要有限数量的样品来进行深入的代谢分析研究，因此本工作的目的是评估该方法在测定肌酐中的实用性使用成人和婴儿的残留血液样本提取少量血浆。通过使用起始量为 5 µL 的血浆和仅 6.7 nL 的进样量，可以获得 30 nM 的肌酐检测限 (S/N = 3)，以及日内和日间精度（峰面积比）均低于3.2%。为了缩短电泳分离时间，采用多段进样 (MSI) 策略在一次电泳运行中分析多达七个样品。将 CE-MS 获得的预处理血浆中肌酐的结果与临床实验室通常用于此目的的酶比色测定法获得的值进行比较。比较表明，CE-MS 可以可靠地用于测定婴儿和成人残留血浆样本中的肌酐。然而，为了强调该方法的临床功效，必须使用扩大的血浆样本库进行后续研究。这不仅将增强该方法的诊断效用，而且有助于最大限度地减少诊断目的所需的血液采集量和频率。