Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Università degli Studi di Milano, Via Celoria 2, 20133 Milano (I), Italy.
Anal Chim Acta. 2009 Nov 23;655(1-2):30-7. doi: 10.1016/j.aca.2009.09.036. Epub 2009 Sep 30.
The limit of detection is a fundamental figure of merit in chemical analysis. Many different approaches are available for its estimation, but only few allow analysing data characterized by a significant change of precision with concentration. Among these, the ISO 11843-2 approach is certainly the most suitable. However, its implementation may not look easy to operators needing to develop the necessary spreadsheets by commercial software packages. This paper is aimed to verifying if alternative approaches are available for getting acceptably approximate estimates of the limit of detection (LOD). Pragmatically, they were set-up by simply adapting some of the approaches already available in the literature, but compatible only with homoscedastic analytical systems. The results obtained by these alternative approaches when analysing a series of calibrations relevant to the electroanalytical determination of hexavalent chromium in some water samples were compared to those furnished by the ISO approach. The results allowed confirming the critical role of the numerosity of the available data on the consistency of any estimate. Even when using the ISO approach, reliable estimates were only obtained by performing a number of calibrations usually uncommon under standard routine conditions. In such a situation, the differences between the results obtained by all the examined approaches appear less important.
检测限是化学分析中的一个基本质量指标。有许多不同的方法可以用来估计它，但只有少数方法允许分析精密度随浓度显著变化的数据。其中，ISO 11843-2 方法无疑是最合适的。然而，对于需要使用商业软件包开发必要电子表格的操作人员来说，其实施可能并不容易。本文旨在验证是否有其他方法可以得到可接受的检测限（LOD）近似估计值。实际上，这些方法是通过简单地适应文献中已经存在的一些方法来设置的，但仅与同方差分析系统兼容。当分析一系列与某些水样中六价铬的电化学测定相关的校准曲线时，这些替代方法得到的结果与 ISO 方法提供的结果进行了比较。结果证实了可用数据数量对任何估计值一致性的关键作用。即使使用 ISO 方法，只有在执行通常在标准常规条件下不常见的一系列校准后，才能得到可靠的估计值。在这种情况下，所有检查方法得到的结果之间的差异似乎不那么重要。
