定量NMR中多种检出限评估方法的比较

Comparison of Different Approaches for Estimation of the Detection Limit of Quantitative NMR

在对核磁共振(Nuclear Magnetic Resonance,NMR)定量检测进行方法验证时,检出限是一项重要的指标.本文对文献中报道的校准曲线法、校准方程参数法、数学模型法、单浓度点评估法进行了系统梳理,重点介绍了这些方法的基本原理、计算公式和特点,并针对信噪比法的不足,提出了信噪比回归曲线法.采用上述五种方法计算了水溶液中甲酸钠^(1)H NMR检测时的检出限,并讨论了采样次数对检出限的影响.在700 MHz核磁共振谱仪上,当采样次数为64时,甲酸钠的检出限在10.4~14.4μmol/L之间.该结果为^(1)H NMR检出限的评估提供了参考.

Limit of detection(LOD),which indicates the detection ability of an analytical method,is an important parameter used in validating quantitative ^(1)H nuclear magnetic resonance(NMR)method.Different approaches to evaluate LOD have been reported in literature,including the calibration curve approach,regression parameters-based approach,ASTM approach(proposed by American Society of Testing Materials),EPA approach(established by the United States Environmental Protection Agency)and the signal-to-noise ratio approach.In this study,systemic analyses and summaries of all mentioned approaches were given together with their principles,equations and characteristics.A novel approach based on signal-to-ratio regression curve for determining the detection limit was proposed,which can overcome weaknesses of the signal-to-noise ratio approach.The LOD of liquid-state ^(1)H NMR method in the determination of sodium formate in aqueous solution was calculated using 5 different approaches.The influence of the number of scans on LOD was discussed.The results showed that the LOD was in the range of 10.4~14.4μmol/L when the number of scans was 64 with 700 MHz NMR spectrometer.In conclusion,the study can provide a reference for determining the LOD of ^(1)H quantitative NMR.