Estimation of measurement uncertainty for the quantitative analysis of pharmaceutical residues in river water using solid-phase extraction coupled with injector port silylation-gas chromatography-tandem mass spectrometry

Abstract

Measurement uncertainty (MU) is associated with analytical methods; it enhances the confidence of the method and helps in improving the quality of the analytical results. The present study aims to estimate MU of an analytical method used for analyzing the pharmaceutical residues in river water by using solid-phase extraction (SPE) followed by auto injector port silylation coupled with gas chromatography-tandem mass spectrometry (IPS-GC-MS/MS) system. The SPE conditions were optimized by using design of experiments approach (Plackett-Burman Design and Central Composite Design); top-down and bottom-up approaches were used for the estimation of MU. The calibration curves of all pharmaceutical residues showed dynamic linearity in the concentration range of 10–2000 ng/L with coefficient of determination (R2) ranging between 0.985 and 0.999. The limit of detection, limit of quantification, and recovery were found to be in the range of 2.52–7.31 ng/L, 8.33–24.12 ng/L and 81.82–114.14%, respectively. The method robustness was found within acceptation limit (<15% RSD) for system suitability. The expanded uncertainty was estimated in the range of 1.28–32.96% for the SPE method. Precision and recovery were identified as major uncertainty sources of SPE-IPS-GC-MS/MS method for the analysis of pharmaceutical residues in river water.