Development of a novel methodology for determination of dialkyl phosphates in human urine using liquid...

In this study a fast and sensitive method was developed for the quantitative determination of six dialkyl phosphates (DAPs) in human urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The proposed methodology was based on liquid-liquid extraction (LLE) with diethyl ether and ethyl acetate using MgSO₄ and NaCl, followed by liquid chromatography and mass spectrometry detection in the selected reaction mode (SRM) with negative electrospray ionization (ESI-). Detection settings were optimized by design of experiments (DoE). Dibutyl phosphate (DBP) was used as internal standard. Several criteria established in the SANTE/11813/2017 guidance document for pesticide residues and analysis in food and feed were used to validate the suggested method: recoveries (R %) between 70 and 120% and coefficients of variation (CV %) ≤ 20%. The procedural limit of quantification (LoQ) was 0.50 ng mL^-1 for the six DAPs. The R% and CV% ranges were 82-117% and 3-20%, respectively. In total, 20 spot urine samples from lactating mothers were satisfactorily analyzed by the proposed analytical strategy.