Development of liquid chromatography methods coupled to mass spectrometry for the analysis of substances with a wide variety of polarity in meconium

Development of a Methodology for Determination of Dioxins and Dioxin-like PCBs in Meconium by Gas Chromatography Coupled to High-Resolution Mass Spectrometry (GC-HRMS)

An analytical strategy was applied to investigate polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in newborn meconium samples. The methodology includes extraction by selective pressurized liquid extraction (SPLE), followed by a clean-up multicolumn step. The samples were injected by gas chromatography coupled to a high-resolution mass spectrometer (GC-HRMS). The surrogate recoveries ranged from 68% to 95%, and the average of the limit of quantification (LOQ) ranged from 0.03 to 0.08 pg g^-1 wet weight (ww) for PCDD/Fs and 0.2 to 0.88 pg g^-1 ww for dl-PCBs. The strategy was applied to 10 samples collected in Valencia (Spain) in 2022. In total, 18 out of 29 analysed congeners were detected in at least one sample, whereas 6 of them were detected in all the samples (OCDD, PCB-123, PCB-118, PCB-105, PCB-167, and PCB-156). The levels for the sum of the 17 congeners of PCDD/Fs and 12 congeners of dl-PCBs in the upper-bound (UB), expressed as picograms of toxic equivalency quantity (TEQ) per gram of ww, ranged from 0.19 to 0.31 pg TEQ g^-1 ww.

Evaluation of Placental Transfer and Tissue Distribution of cis- and Trans-Permethrin in Pregnant Rats and Fetuses Using a Physiological-Based Pharmacokinetic Model

Biomonitoring studies have highlighted the exposure of pregnant women to pyrethroids based on the measurement of their metabolites in urine. Pyrethroids can cross the placental barrier and be distributed in the fetus as some pyrethroids were also measured in the meconium of newborns. Prenatal exposure to pyrethroids is suspected to alter the neurodevelopment of children, and animal studies have shown that early life exposure to permethrin, one of the most commonly used pyrethroid in household applications, can alter the brain development. This study aimed to characterize the fetal permethrin exposure throughout gestation in rats. We developed a pregnancy physiologically based pharmacokinetic (pPBPK) model that describes the maternal and fetal kinetics of the cis- and trans- isomers of permethrin during the whole gestation period. Pregnant Sprague-Dawley rats were exposed daily to permethrin (50 mg/kg) by oral route from the start of gestation to day 20. Permethrin isomers were quantified in the feces, kidney, mammary gland, fat, and placenta in dams and in both maternal and fetal blood, brain, and liver. Cis- and trans-permethrin were quantified in fetal blood and tissues, with higher concentrations for the cis-isomer. The pPBPK model was fitted to the toxicokinetic maternal and fetal data in a Bayesian framework. Several parameters were adjusted, such as hepatic clearances, partition coefficients, and intestinal absorption. Our work allowed to estimate the prenatal exposure to permethrin in rats, especially in the fetal brain, and to quantitatively estimate the placental transfer. These transfers could be extrapolated to humans and be incorporated in a human pPBPK model to estimate the fetal exposure to permethrin from biomonitoring data.

Monitoring of prenatal exposure to organic and inorganic contaminants using meconium from an Eastern Canada cohort

Evaluating in utero exposure to inorganic and multiclass organic contaminants is critical to better evaluate potential harmful effects on prenatal and postnatal development. The analysis of meconium, the first bowel discharge of the newborn, has been proposed as a non-invasive way to assess cumulative prenatal exposure. The aim of this study was to implement an analytical method for quantifying 72 targeted organic compounds, including pesticides, pharmaceutical compounds and daily life xenobiotics, in meconium in addition to selected elements (17 elements). We report initial monitoring results based on the analysis of 396 meconium samples from an Eastern Canada cohort (Quebec, Canada). Element contents in meconium were analysed by mass spectrometry after digestion in nitric acid and peroxide. Targeted organic compounds were extracted and purified from meconium samples by a solid-liquid extraction followed by a dispersive-SPE purification before tandem mass spectrometry analysis. Concentrations of targeted elements were within the range of concentration reported in European and US studies but were lower than concentrations found in a developing country cohort (i.e., Pb, Cd). Out of the 72 targeted organic compounds, 31 were detected at least once and 30 were quantified. Compounds with the highest frequency of detection were caffeine, detected in all samples (from 2.80 to 6186 ng g-1), followed by acetaminophen detected in 53% of the samples (up to ~402 µg g-1) and methyl paraben detected in 20% of the samples (up to ~10 µg g-1). Pesticides were detected in low frequencies (< 2%) and low concentration (< 35 ng g-1). Results show that meconium can be used to monitor prenatal exposure of foetus to a wide array of inorganic and organic contaminants.

Screening for Polar Chemicals in Water by Trifunctional Mixed-Mode Liquid Chromatography-High Resolution Mass Spectrometry

The presence of persistent and mobile organic contaminants (PMOC) in aquatic environments is a matter of high concern due to their capability of crossing through natural and anthropogenic barriers, even reaching drinking water. Most analytical methods rely on reversed-phase liquid chromatography (RPLC), which is quite limited for the detection of very polar chemicals. Thus, many of these PMOCs may have not been recognized as water pollutants yet, due to the lack of analytical methods capable to detect them. Mixed-mode LC (MMLC), providing the combination of RP and ion-exchange functionalities is explored in this work with a trifunctional column, combining RPLC, anion and cation exchange, which allows the simultaneous determination of analytes with extremely different properties. A nondiscriminant sample concentration step followed by a MMLC-high resolution mass spectrometry method was developed for a group of 37 very polar model chemicals with different acid/base functionalities. The overall method performance was satisfactory with a mean limit of detection of 50 ng/L, relative standard deviation lower than 20% and overall recoveries (including matrix effects) higher than 60% for 54% of model compounds. Then, the method was applied to 15 real water samples, by a suspect screening approach. For those detected PMOC with standard available, a preliminary estimation of concentrations was also performed. Thus, 22 compounds were unequivocally identified in a range of expected concentrations from 6 ng/L to 540 μg/L. Some of them are well-known PMOC, such as acesulfame, perfluorobutanoic acid or metformin, but other novel pollutants were also identified, as for example di-o-tolylguanidine or trifluoromethanesulfonic acid, which had not or were scarcely studied in water so far.