Biomonitoring urinary pesticide metabolites in preschool children by supported liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry and their association with oxidative stress

Investigating pesticide exposure and oxidative stress in preschool children is essential for elucidating the determinants of environmental health in early life, with human biomonitoring of urinary pesticide metabolites serving as a critical strategy for achieving this objective. This study demonstrated biomonitoring of 2 phenoxyacetic acid herbicides, 2 organophosphorus pesticide metabolites, and 4 pyrethroid pesticide metabolites in 159 preschool children and evaluated their association with oxidative stress biomarker 8-hydroxydeoxyguanosine. An enzymatic deconjugation process was used to release urinary pesticide metabolites, which were then extracted and enriched by supported liquid extraction, and quantified by ultra-high performance liquid chromatography-tandem mass spectrometry with internal standard calibration. Dichloromethane: methyl tert‑butyl ether (1:1, v/v) was optimized as the solvent for supported liquid extraction, and we validated the method for linear range, recovery, matrix effect and method detection limit. Method detection limit of the pesticide metabolites ranged from 0.01 μg/L to 0.04 μg/L, with satisfactory recoveries ranging from 70.5 % to 95.5 %. 2,4,5-Trichlorophenoxyacetic acid was not detected, whereas the other seven pesticide metabolites were detected with frequencies ranging from 10.1 % to 100 %. The concentration of urinary pesticide metabolites did not significantly differ between boys and girls, with the median concentrations being 9.39 μg/L for boys and 4.90 μg/L for girls, respectively. Spearman correlation analysis indicated that significant positive correlations among urinary metabolites. Bayesian kernel machine regression revealed a significant positive association between urinary pesticide metabolites and 8-hydroxydeoxyguanosine. Para-nitrophenol was the pesticide metabolite that contributed significantly to the elevated level of oxidative stress.

[Determination of phenylglyoxylic acid and mandelic acid in urine by ultra high performance liquid chromatography tandem mass spectrometry]

Objective: To develop a method for the analysis of phenylglyoxylic acid (PGA) and mandelic acid (MA) in urine by ultra-high performance liquid chromatography tandem mass spectrometry. Methods: The study was conducted in April 2022. Urine samples were directly diluted with the initial mobile phase, separated by Waters HSS T3 column after passing through the membrane, and analyzed under negative ionization mode (ESI(-)) and multiple reaction monitoring (MRM) conditions, the contents of PGA and MA in human urine were quantitatively determined by external standard method. Results: The determination of PGA and MA showed a good linear relationship within the range of 10-1000 ng/ml, with a correlation coefficient of 0.9999. The linear regression equation of PGA was y=1141.4x+2157.3, the detection limit and lower limit of quantification of the method were 0.081 ng/ml and 0.269 ng/ml, and the recovery rate was 90.47%-99.83%. The linear regression equation of MA was y=62.8x+140.3, the detection limit and lower limit of quantification of the method were 0.551 ng/ml and 1.836 ng/ml, and the recovery rate was 92.75%-101.09%. The intra and inter batch precision of PGA and MA were both<5%. Conclusion: An ultra-high performance liquid chromatography tandem mass spectrometry method for the analysis of PGA and MA in urine was established.The sample pretreatment operation is simple, and the accuracy and precision of the method meet the standard requirements. It can be used for monitoring and evaluating PGA and MA in urine of the general population and occupational contact population.

Supported liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry for the determination of urinary polycyclic aromatic hydrocarbon metabolites and their application for human biomonitoring

Polycyclic aromatic hydrocarbons (PAHs) are a class of highly lipophilic and ubiquitous, persistent organic pollutants with carcinogenic and mutagenic toxicities. They are a great public health concern, and avoiding exposure to them is a high priority. Human biomonitoring is critical for the evaluation of exposure levels to PAHs by the general population. In this work, we demonstrated the biomonitoring of eleven hydroxylated PAHs (OHPAHs) in urine samples from 226 volunteers from Guangzhou, and evaluated the health risks. The urinary PAH metabolites were released by enzymatic deconjugation, separated, and enriched by supported liquid extraction, and then quantified by ultra-high performance liquid chromatography-tandem mass spectrometry. The limit of quantification of the individual OHPAHs ranged from 10 ng/L to 40 ng/L, and satisfactory recoveries were obtained, ranging from 92.6% to 97.6%. The detection frequencies of the OHPAHs were 100%, and naphthalene metabolites were found at the highest concentrations with a geometric mean of 8.61 μg/L. The mean total OHPAH level in the urine samples of males (13.2 μg/L) was significantly higher than that of females (5.84 μg/L). Pearson correlation analyses indicated significant and positive correlations among urinary OHPAHs. The total estimated daily intake of PAHs was calculated, and a low health risk was obtained by evaluating their hazard quotients and hazard indexes.

Simultaneous determination of multiple isomeric hydroxylated polycyclic aromatic hydrocarbons in urine by using ultra-high performance liquid chromatography tandem mass spectrometry

Monitoring the level of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in urine is the key to exploring human metabolic changes and comprehensive potential toxicity of PAHs. The OH-PAHs with isomeric structure have different biological functions, indicating that their quantification is indispensable. However, the quantitation method is still dissatisfactory due to the poor separation of these isomeric OH-PAHs. The current study established a ultra-high performance liquid chromatography (UHPLC) tandem mass spectrometry (MS) method to complete the simultaneous determination of 17 OH-PAHs, including two naphthalene metabolites (1-hydroxynaphthalene, 2-hydroxynaphthalene), two fluorene metabolites (2-hydroxyfluorene, 3-hydroxyfluorene), five phenanthrene metabolites (1-hydroxyphenanthrene, 2-hydroxyphenanthrene, 3-hydroxyphenanthrene, 4-hydroxyphenanthrene, 9-hydroxyphenanthrene), a pyrene metabolite (1-hydroxypyrene), five chrysene metabolites (1-hydroxychrysene, 2-hydroxychrysene, 3-hydroxychrysene, 4-hydroxychrysene, 6-hydroxychrysene) and two benzo[a]pyrene metabolites (3-hydroxybenzo[a]pyrene, 9-hydroxybenzo[a]pyrene). The method validation results showed good selectivity, linearity (r² > 0.999), inter-day and intra-day precision (relative standard deviation (RSD) < 5.5% and RSD < 6.3%), stability (RSD < 19.3%), matrix effect (-8.3%-11.5%) and recovery (65.9%-116.2%). This method is convenient, sensitive and efficient, saving expensive materials and complicated derivatization procedures. The practical applicability of developed approach was also tested in urine samples to identify potential biomarkers of PAHs exposure in humans, and a great compromise was obtained between recoveries and extract convenience. The developed approach may be widely utilized for specific determination of OH-PAHs with isomer structure in urine samples. It is expected that the application of this method may provide powerful references for PAHs exposure assessment.

An optimized LC-MS/MS method for determination of HYNIC-3PRGD2, a new promising imaging agent for tumor targeting, in rat plasma and its application

HYNIC-3PRGD₂ is used to prepare a new ^99mTc-radiolabeled tracer. HYNIC-3PRGD₂, which has a high binding affinity for the integrin α_vβ₃ due to its special structure, has become a promising tumor imaging agent for diagnosis and monitor of the clinical response to therapeutic effects of anti-tumor agents. Here, we developed and validated a method for determination of HYNIC-3PRGD₂ concentration in rat plasma using ultra-high performance liquid chromatography-tandem mass spectrometry system. Following sample extraction by methanol precipitation, satisfactory separation through chromatography was achieved on an hydrophilic reverse-phase C₁₈ column AQ (2.1 mm × 100 mm, 2.7 μm) at a flow rate of 0.2 mL·min^-1 with an gradient elution using mobile phase consisting of ultrapure water and acetonitrile fortified with 0.1% formic acid respectively. The calibration curve was developed over a linear range of 3.125-100 ng·mL^-1 with the lower limit of quantification of 3.125 ng·mL^-1. The HYNIC-3PRGD₂ and its internal standard c(RGDfK)(RK5) were detected and quantified with the multiple reaction monitoring (MRM) mode on a triple-quadrupole tandem mass spectrometer. This method was successfully validated and applied for pharmacokinetic evaluation of HYNIC-3PRGD₂ during pre-clinical experiments.

Widely targeted metabolomics of Alzheimer's disease postmortem cerebrospinal fluid based on 9-fluorenylmethyl chloroformate derivatized ultra-high performance liquid chromatography tandem mass spectrometry

Confirmed biomarkers of postmortem cerebrospinal fluid (pCSF) are used to differentiate between Alzheimer's disease (AD) patients and healthy seniors with high diagnostic accuracy. However, the extent to which the performance of specific metabolic profiling facilitates reliable estimations of the concentrations of the different pCSF biomarkers and their ratios remains unclear. The interpretation of the lower levels of molecules of metabolic profiling and their concentration ratios in pCSF related to brain disorders could facilitate an unchallenging detection of peripheral biomarkers of AD stages and other dementia types. In this study, we proposed the use of widely targeted metabolomics for pCSF metabolic profiling using 9-fluorenylmethyl chloroformate- (FMOC) derivatized ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to evaluate the diversity of 97 amine-mediated metabolic patterns and pathways from confirmed diagnosis based on AD brain pathology. Our results identified the metabolites that contributed toward and mutually influenced the principal component analysis plot with integrated analytes. Furthermore, the AD group showed a significant variation in several analyte concentration levels compared to those of control subjects. These trends of the concentration levels expressed by the amine metabolic pathways indicated the decreased activity of polyamine and tryptophan-kynurenine (Trp-Kyn) metabolisms. Moreover, increased metabolites such as methionine sulfoxide, 3-methoxy-anthranilate, cadaverine, guanine, and histamine were observed by widely targeted metabolomics of pCSF from the AD subjects. According to their metabolic pathway analysis using FMOC-derivatized UHPLC-MS/MS assay, we supposed that the involvement of polyamine and Trp-Kyn metabolisms was observed in the pCSF samples.

Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) for determination of GHB, precursors and metabolites in different specimens: Application to clinical and forensic cases

Gamma-hydroxybutyric acid (GHB) acts as a precursor and metabolite of the inhibitory central nervous system (CNS) neurotransmitter gamma-aminobutyric acid (GABA). Sodium salt of GHB has been used as a medication for narcolepsy and alcohol withdrawal. Moreover, GHB and its precursor gamma-butyrolactone (GBL), are illegal recreational drugs of abuse. A procedure based on ultra-high-performance liquid chromatography tandem mass spectrometry has been developed and validated in plasma, urine, cerebrospinal fluid and hair for acute and chronic exposure to GHB and in seized preparations coming from black market. In biological matrices, GHB was investigated together with its glucuronide (GHB-Gluc) as a potential marker of exposure, GABA as endogenous precursor and metabolite and GBL as eventual exogenous precursor. GBL was sought together with GHB in illegal preparations. Chromatographic separation was achieved at ambient temperature using a reverse-phase column and an isocratic elution with two solvents: 0.1% formic acid in water and pure methanol. Multiple reaction monitoring (MRM) was used. The method was linear for all analytes under investigation from limit of quantification (LOQ) to 500μgmL^-1 plasma, urine and cerebrospinal fluid, from LOQ to 100ngmg^-1 hair and from LOQ to 10mgmL^-1 illicit preparations with good correlation coefficients (r²=0.99) for all substances. Recovery of analytes under investigation was always higher than 75% and intra-assay and inter-assay precision and accuracy were always better than 15%. The validated method was then successfully applied to real specimens from either forensic (one post-mortem urine sample taken from a GHB fatal intoxication case) or clinical cases (cerebrospinal fluid, plasma and hair samples collected from narcoleptic patients under sodium oxybate treatment). Finally, illicit preparations, seized by police forces were also checked for GHB amount and eventual presence of prodrug GBL.