Abstract:

Accurate and reliable analytical methods are fundamental to ensuring the validity and reproducibility of scientific results， particularly in research involving trace-level contaminants in biological samples. While standardized methods regulated by official guidelines are commonly used in certified laboratories， research laboratories often rely on in-house or self-developed non-standard methods tailored for specific studies. These methods， however， frequently lack harmonized validation criteria， especially regarding accuracy evaluation. Traditionally， method accuracy is assessed through single performance indicators such as recovery， relative standard deviation （RSD）， or bias. These indicators， although useful， may vary widely in their interpretation and offer limited insight into overall method performance， particularly when comparing between laboratories or over different concentration ranges. To address these limitations， the Société Française des Sciences et Techniques Pharmaceutiques （SFSTP） introduced the accuracy profile approach. This method integrates both trueness and precision using a statistical model to generate β-expectation tolerance intervals， allowing a visual and comprehensive representation of whether an analytical method meets predefined acceptance criteria across multiple concentration levels. Unlike traditional evaluations， which may obscure marginal performance failures， the accuracy profile provides a single， unified framework that simplifies interpretation and decision-making. In this study， we applied the SFSTP accuracy profile approach to validate a high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） method for quantifying 20 urinary phenols. Method performance was assessed at three concentration levels （low， medium， and high） and the results were compared with conventional validation methods. The intra-batch RSD values ranged from 2.8% to 10.7%， and inter-batch RSD values ranged from 3.3% to 14.4%. The pooled intermediate precision RSD ranged from 4.9% to 16.6%， indicating acceptable reproducibility. Relative errors were between -25.3% and 13.0%， According to traditional evaluation using single parameters， the accuracy of all 20 phenol measurements met standard criteria. However， accuracy profile analysis revealed that only 13 phenols， such as bisphenol AF and bisphenol B， had β-expectation tolerance intervals entirely within the ±30% acceptance limits across all tested concentration levels. The remaining seven phenols， including benzylparaben and benzophenone-8， exceeded acceptable limits at low or medium concentrations， suggesting areas for method optimization. In conclusion， this study demonstrates that the HPLC-MS/MS method provides reliable quantitative results for the majority of tested urinary phenols. More importantly， the SFSTP accuracy profile offers a superior alternative to conventional validation methods by combining accuracy parameters and risk analysis into a coherent， statistically sound framework. This approach enables researchers to clearly identify the strengths and weaknesses of analytical methods without increasing experimental complexity or cost. Its advantages in standardization， interpretability， and decision-making support its broader adoption for validating non-standard methods in research and applied laboratories.

Key words: accuracy assessment, β-expectation tolerance intervals, urinary phenols, high performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS）