Nontargeted LC-HRMS-Based Strategies as a Tool to Study the Behavior of Chemical Attribution Signatures of Organophosphorus in Complex Environmental Matrices.

Biomonitoring: a demonstration of the importance of direct analytical methods for the assessment of chemical exposures

Biomonitoring of commercial endocrine-disrupting chemicals (EDCs) increasingly underpins exposure assessment and risk evaluation, yet most large-scale studies still rely on indirect, enzymatic hydrolysis–based methods whose quantitative performance has not been systematically verified. Here, we describe the development and rigorous validation of a direct liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay using validated standards to simultaneously quantify bisphenol S (BPS), propylparaben (PrP), monobutyl phthalate (MBP), and their major urinary glucuronide and sulfate conjugates in human urine. A direct LC–MS/MS assay was developed for the simultaneous quantification of BPS, PrP, MBP and their major urinary metabolites. The method was validated in accordance with U.S. Food and Drug Administration bioanalytical guidelines, including assessments of linearity, accuracy, precision, selectivity, specificity, matrix effects, recovery, and carryover. The validated assay was then used to evaluate the accuracy of a conventional β‐glucuronidase–based hydrolysis workflow across a wide concentration range in spiked synthetic urine by comparing indirect measurements with direct totals for each analyte. Method utility in human biomonitoring was demonstrated by analysis of urine samples from 30 pregnant women in their second trimester. Using isotope-dilution calibration, solid-phase extraction, and negative-ion electrospray multiple reaction monitoring, the method achieved sub‐ng/mL limits of detection for all analytes, linear response over 3-4 orders of magnitude, and intra‐ and inter‐day precision and accuracy within contemporary bioanalytical criteria, confirming fitness for trace-level biomonitoring. Indirect, hydrolysis-based measurements closely tracked direct totals for BPS and PrP, but systematically underestimated MBP, with a concentration-dependent negative bias that increased at higher levels, demonstrating that hydrolysis efficiency is analyte-specific and cannot be inferred from surrogate substrates alone. Application of the direct method to archived urine samples from 30 pregnant individuals enabled the first simultaneous resolution of the free and conjugated forms of these three EDCs in a maternal cohort and revealed that glucuronides accounted for the majority of the total urinary burden, with total concentrations exceeding contemporary NHANES estimates. Collectively, these findings show that indirect methods can introduce substantial, analyte-dependent underestimation of internal dose, with implications for exposure misclassification, attenuation of epidemiologic effect estimates, and underestimation of population risk. The data support the position that direct LC–MS/MS quantification of parent and conjugated species, coupled with analyte-resolved assessment of hydrolysis efficiency, should become standard practice in method validation and national biomonitoring programs to ensure accurate exposure assessment for non‐persistent EDCs.

Multi-class UHPLC-MS/MS method for the simultaneous determination of 32 endocrine-disrupting chemicals in the urine of pregnant women.

A Generic Approach for Simultaneous Screening and Quantification of Aflatoxins and Pesticide Residues in Rice by LC-MS/MS: Single Laboratory Validation.

BACKGROUND Chemical residues in rice require highly sensitive analytical methods to verify compliance with stringent residue limits. In addition to pesticide residues, aflatoxins are critical contaminants due to their toxicity and carcinogenicity. OBJECTIVE To develop and validate a simple, generic LC-MS/MS workflow for simultaneous screening and quantification of pesticide residues and aflatoxins in rice. METHODS Samples were extracted using a modified QuEChERS EN 15662:2018 procedure with acidified acetonitrile, followed by dispersive solid-phase extraction cleanup. Analysis was performed using a UHPLC coupled to a triple quadrupole mass spectrometer (QQQ) with heated electrospray ionization in time-scheduled selected reaction monitoring mode. Method performance was assessed in accordance with SANTE guidance using matrix-matched calibration. RESULTS The optimized LC-MS/MS method demonstrated many transitions with polarity switching while maintaining acceptable chromatographic peak quality and selectivity. Acidified extraction improved the response by 3- 5-fold for the selected analytes. The method achieved LOQs of 0.0005 mg/kg for pesticides and aflatoxins. Calibration was linear over 0.0005-0.050 mg/kg for pesticides and 0.0002-0.010 mg/kg (0.2 -10 µg/kg) for aflatoxins, with R² ≥ 0.99 and residuals within ±20%. Recoveries for all target analytes were within 70- 120%, with precision ≤20% RSD at the evaluated spike levels. CONCLUSIONS The proposed single-extraction LC-MS/MS workflow is selective, sensitive, accurate, and suitable for the simultaneous high-throughput determination of pesticide residues and aflatoxins in rice. The method meets SANTE criteria for pesticides, complies with the Commission Implementing Regulation (EU) 2023/2782 for aflatoxins, and complies with FSSAI and EU MRLs/MLs for rice.

Monitoring of BTEX levels in saliva and urine using optimized MWCNTs/ATSB nanocomposite fibers: a comparative study on benzene-steroid hormones interaction

Analytical method development for twenty-one analytically challenging and under-investigated pesticides in drinking water.

Analytically challenging pesticides and biocides remain underrepresented in routine drinking water (DW) monitoring because of their diverse physicochemical properties and associated analytical constraints. Consequently, their occurrence and potential contribution to human exposure remain poorly documented. This study developed and validated complementary analytical methods for the determination of twenty-one under-investigated pesticides, including biocides, in DW. Twenty compounds were determined by online solid-phase extraction coupled to high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS), while only one compound was analyzed by direct injection ion chromatography-tandem mass spectrometry (DI-IC-MS/MS). Method validation was performed according to NF T90-210 and ISO 21253 standards using six representative DW matrices. The validated methods demonstrated satisfactory analytical performance, with limits of quantification (LOQ) ranging from 1.2 to 100 ng L-1, quadratic calibration models (R2 > 0.98), relative recoveries generally between 80 and 120%, acceptable relative bias, intermediate precision below 30%, and expanded measurement uncertainties generally below 50%, although values of up to 60% were observed for some analytes. The methods were subsequently applied to 313 DW samples collected during a nationwide French monitoring campaign from DW systems supplying approximately 20-25% of the population. Among the twenty-one target compounds, only fluopyram was quantified, and only in a single sample, at 11 ng L-1, while no other target compound was quantified among the samples for which a valid analytical result was available. These findings are consistent with national occurrence databases, which indicate extremely low quantification frequencies (QFs) for most investigated substances. The developed methods provide robust tools for routine monitoring of the investigated parent compounds and establish a framework for future studies incorporating relevant transformation products in DW.

Development of a dual LC-MS/MS platform for comprehensive monitoring of the photocatalytic transformation products of cyantraniliprole in wastewater effluents.

Cyantraniliprole (CYA) is a second-generation anthranilic diamide insecticide whose increasing use in non-agricultural and urban settings poses a challenge for wastewater treatment plants (WWTPs). Given its low expected concentration and the potential formation of stable residues, the development of highly sensitive and selective analytical methods is essential. In this study, a comprehensive methodology was developed to monitor CYA and its transformation products (TPs) in wastewater effluents. The analytical strategy integrates dispersive liquid-liquid microextraction with a dual liquid chromatography with mass spectrometry (LC-MS/MS) platform, consisting of triple quadrupole (QqQ) and quadrupole time-of-flight (QTOF) analyzers. Using suspect and non-target screenings, eight TPs were tentatively identified based on high-resolution mass measurements and characteristic isotopic patterns. This structural elucidation allowed for the proposal of a detailed photocatalytic (TiO2) degradation pathway under ultraviolet A (UVA) provided by light emitting diode (LED) lamps, where an 86% degradation of the parent compound was achieved within 19 h. The methodology was subsequently validated and applied to real WWTP effluents previously fortified at 0.2 mg L-1 and subjected to solar photocatalysis (TiO2/Na2S2O8 tandem). In these complex matrices, CYA was quantified in the range of 0.07 to 0.14 mg L-1, and three principal TPs were consistently identified across all effluents. Specifically, IN-J9Z38, IN-HGW87, and IN-M2G98 emerged as the primary stable environmental markers, whereas two additional TPs (OH-CYA1 and CYA487) occurred only at trace levels with lower spectral information. Finally, an in silico environmental risk assessment characterized the insecticide and a selection of its main TPs as persistent and mobile species in the water column.