Optimized extraction and analysis methods using liquid chromatography-tandem mass spectrometry for zearalenone and metabolites in human placental tissue.

Zearalenone and its metabolites, a group of endocrine disrupting mycotoxins, have been linked to adverse reproductive health effects. They cross the placental barrier, potentially reaching the fetus. In this study, we adapted and optimized our protocol previously used for urine, to measure these mycotoxins in human placentas. We combined a supported liquid extraction step using Chem Elut cartridges with solid phase extraction on Discovery® DSC-NH2 tubes. The optimized extraction efficiencies were between 68 and 80% for all metabolites. Analysis was performed by UHPLC-HRMS using a Betasil™ Phenyl-Hexyl column eluted with a gradient of acetonitrile-methanol-water. The chromatography method separated all analytes in under 15 min. Validation experiments confirmed the method's sensitivity, with LODs ranging from 0.0055 to 0.011 pg/mg tissue. The method was linear over a range of 0.0025-1.5 pg/mg tissue with R2 values ≥ 0.994. Precision and accuracy calculations ranged from 4.7-7.9% and 0.6-6.7% respectively. The method was then successfully applied to a subset of placenta samples (n = 25) collected from an ongoing prospective birth cohort. Interestingly, 92% of the samples contained at least one measurable zearalenone metabolite, providing initial indication of potentially widespread exposure during pregnancy.

A comparison of four liquid chromatography-mass spectrometry platforms for the analysis of zeranols in urine.

Targeted biomonitoring studies quantifying the concentration of zeranols in biological matrices have focused on liquid chromatography interfaced to mass spectrometry (LC-MS). The MS platform for measurement, quadrupole, time-of-flight (ToF), ion trap, etc., is often chosen based on either sensitivity or selectivity. An instrument performance comparison of the benefits and limitations using matrix-matched standards containing 6 zeranols on 4 MS instruments, 2 low-resolution (linear ion traps), and 2 high-resolution (Orbitrap and ToF) was undertaken to identify the best measurement platform for multiple biomonitoring projects characterizing the endocrine disruptive properties of zeranols. Analytical figures of merit were calculated for each analyte to compare instrument performance across platforms. The calibration curves had correlation coefficients r = 0.989 ± 0.012 for all analytes and LODs and LOQs were ranked for sensitivity: Orbitrap > LTQ > LTQXL > G1 (V mode) > G1 (W mode). The Orbitrap had the smallest measured variation (lowest %CV), while the G1 had the highest. Instrumental selectivity was calculated using full width at half maximum (FWHM) and as expected, the low-resolution instruments had the broadest spectrometric peaks, concealing coeluting peaks under the same mass window as the analyte. Multiple peaks from concomitant ions, unresolved at low resolution (within a unit mass window), were present but did not match the exact mass predicted for the analyte. For example, the high-resolution platforms were able to differentiate between a concomitant peak at 319.1915 from the analyte at 319.1551, included in low-resolution quantitative analyses demonstrating the need to consider coeluting interfering ions in biomonitoring studies. Finally, a validated method using the Orbitrap was applied to human urine samples from a pilot cohort study.

Recent Trends in Multiclass Analysis of Emerging Endocrine Disrupting Contaminants (EDCs) in Drinking Water.

Ingestion of water is a major route of human exposure to environmental contaminants. There have been numerous studies exploring the different compounds present in drinking water, with recent attention drawn to a new class of emerging contaminants: endocrine-disrupting compounds (EDCs). EDCs encompass a broad range of physio-chemically diverse compounds; from naturally occurring to manmade. Environmentally, EDCs are found as mixtures containing multiple classes at trace amounts. Human exposure to EDCs, even at low concentrations, is known to lead to adverse health effects. Therefore, the ability to evaluate EDC contamination with a high degree of sensitivity and accuracy is of the utmost importance. This review includes (i) discussion on the perceived and actual risks associated with EDC exposure (ii) regulatory actions that look to limit EDC contamination (iii) analytical methods, including sample preparation, instrumentation and bioassays that have been advanced and employed for multiclass EDC identification and quantitation.

A surface sampling and liquid chromatography mass spectrometry method for the analysis of quaternary ammonium compounds collected from public transportation buses in New Jersey.

Quaternary ammonium compounds (QACs) are a class of antimicrobial disinfectants whose use in cleaning products increased during the COVID-19 pandemic. Chemically, their low vapor pressure indicates a proclivity to persist on surfaces, and their presence suggests a level of protection against microorganisms. The widespread application of QACs in response to the SARS CoV-2 virus created a need to evaluate their longevity on surfaces, for both efficacy and possible health risks. There are however, no standardized analytical methods for QAC surface sampling and analysis, and no published studies quantifying their concentrations on mass transportation vehicles-a high occupancy, close-contact microenvironment documented to facilitate the spread the SARS CoV-2 virus. Here, we describe a robust liquid chromatography mass spectrometry (LC-MS) method for the analysis of QACs and simultaneous development of a direct surface sampling and extraction protocol. We demonstrate the applicability of the method through the analysis of surface samples collected from in-service public transportation buses. The rapid, sensitive LC-MS method included 8 target QACs quantified on a Q-Exactive HF Hybrid Quadrupole-Orbitrap mass spectrometer using an electrospray ionization source and Dionex UltiMate 3000 UHPLC system for analyte separation. QAC standard mixtures at concentrations between 0.1 ng mL-1 and 2000 ng mL-1 were analyzed, and chromatographic separation of all analytes was achieved in less than 10 min. All correlation coefficients were reported at r > 0.986, and LODs ranged from 0.007 to 2.103 ng mL-1 for all compounds, confirming the method's sensitivity. A previously reported surface sampling and extraction protocol was modified to further simplify the procedure and expand the number of target compounds. The new sampling protocol was optimized from 10 commercially available wipes and 4 solvent types by quantifying recovery from the surface. Band-Aid brand small gauze pads saturated with isopropanol had the highest recovery efficiencies, ranging from 61.5 to 102.9% across all analytes. To test the real-world applicability, wipe samples were collected from 4 in-circulation New Jersey Transit buses on 5 separate days over the course of a month to assess the occurrence and longevity of QACs on sanitized mass transportation vehicles. Concentrations of QACs were detected on every wipe sample taken, and at all sampled time points, confirming their persistence on hard surfaces. QACs have the potential to form polymers, and detection of the polymer might serve as a secondary indication of their effectiveness on surfaces. None of the polymers detected however, were unique to QACs from this study. The polymers detected were already present in the wipe and used as an internal standard to demonstrate the efficacy of extraction and analysis of polymeric QACs.