Reliable creatinine measurements are important to evaluate kidney function and for creatinine correction to reduce biological variability of other urinary analytes. A high-throughput, accurate liquid chromatography tandem mass spectrometry method for quantitation of human urinary creatinine has been developed and validated.

Sample preparation was fully automated including cryovial decapping, sample ID scanning and two serial dilution steps. Quantitation was performed using a stable isotope-labeled internal standard. Multiplexed chromatographic separation of creatinine was achieved within a one-minute analysis and followed by tandem mass spectrometry in positive electrospray ionization mode. The precursor and product ions of creatinine and D₃-creatinine were monitored in selected reaction monitoring mode.

Method validation results showed reproducibility with within-run precision of 3.59, 3.49 and 2.84% and between-run precision of 4.01, 3.28 and 3.57% for low, medium and high quality control materials prepared from pooled donor urine, respectively. The method showed excellent accuracy with a bias of −1.94%, −0.78% and −1.07% for three levels of certified reference material. The calibration curve was linear throughout a 7.50–300 mg/dL (0.663–26.5 mmol/L) measurement range (R² = 0.999), with the mean slope of 0.0115 (95%CI, 0.0108–0.0122) and intercept of 0.0027 (95%CI, 0.0003–0.0051). The limit of detection (LOD) of the method was 3.17 mg/dL (0.280 mmol/L). Analytical specificity was achieved by chromatographically separating creatinine from potentially interfering creatine within a one-minute run and monitoring the Quantitation Ion/Confirmation Ion (QI/CI) ratios in samples.

A simple, accurate, high-throughput method was successfully developed for measuring creatinine in human urine samples.

可靠的肌酐测量对于评估肾功能和肌酐校正以减少其他尿液分析物的生物变异性非常重要。一种用于定量人尿肌酐的高通量、准确的液相色谱串联质谱方法已经开发出来并得到验证。

样品制备完全自动化，包括冷冻管开盖、样品 ID 扫描和两个连续稀释步骤。使用稳定同位素标记的内标进行定量。一分钟的分析内实现了肌酸酐的多重色谱分离，然后在正电喷雾电离模式下进行串联质谱分析。在选定的反应监测模式下监测肌酐和D _{3 -肌酐的前体离子和产物离子。}

方法验证结果显示，对于从汇集的供体尿液中制备的低、中和高质量对照材料，其重复性分别为 3.59、3.49 和 2.84%，批间精密度分别为 4.01、3.28 和 3.57%。该方法显示出出色的准确性，三个级别的认证标准物质的偏差分别为 -1.94%、-0.78% 和 -1.07%。校准曲线在 7.50–300 mg/dL (0.663–26.5 mmol/L) 测量范围内呈线性 (R ²  = 0.999)，平均斜率为 0.0115 (95%CI, 0.0108–0.0122)，截距为 0.0027 ( 95%CI，0.0003–0.0051）。该方法的检测限（LOD）为3.17 mg/dL（0.280 mmol/L）。通过在一分钟运行内色谱分离肌酐与潜在干扰肌酸并监测样品中的定量离子/确认离子 (QI/CI) 比率来实现分析特异性。

成功开发了一种简单、准确、高通量的方法来测量人体尿液样本中的肌酐。