Serum untargeted lipidomic characterization in a general Chinese cohort with residual per-/polyfluoroalkyl substances by liquid chromatography-drift tube ion mobility-mass spectrometry.

Per- and polyfluoroalkyl substances (PFAS) remain controversial due to their high persistency and potential human toxicity. Although occupational exposure to PFAS has been widely investigated, the implications of PFAS occurrence in the general population remain to be unraveled. Considering that serum from most people contains PFAS, the aim of this study was to characterize the lipidomic profile in human serum from a general cohort (n = 40) with residual PFAS levels. The geometric means of ∑PFAS (11.8 and 4.4 ng/mL) showed significant differences (p < 0.05) for the samples with the highest (n = 20) and lowest (n = 20) concentrations from the general population respectively. Reverse-phase liquid chromatography coupled to drift tube ion mobility and high-resolution mass spectrometry using dual polarity ionization was used to characterize the lipid profile in both groups. The structural elucidation involved the integration of various parameters, such as retention time, mass-to-charge ratio, tandem mass spectra and collision cross section values. This approach yielded a total of 20 potential biomarkers linked to the perturbed glycerophospholipid metabolism, energy metabolism and sphingolipid metabolism. Among these alterations, most lipids were down-regulated and some specific lipids (PC 36:5, PC 37:4 and PI O-34:2) exhibited a relatively strong Spearman correlation and predictive capacity for PFAS contamination. This study could support further toxicological assessments and mechanistic investigations into the effects of PFAS exposure on the lipidome.

A comparison of hydrophilic interaction liquid chromatography and capillary electrophoresis for the metabolomics analysis of human serum.

Cationic, anionic, zwitterionic and, partially polar metabolites are very important constituents of blood serum. Several of these metabolites underpin the core metabolism of cells (e.g., Krebs cycle, urea cycle, proteins synthesis, etc.), while others might be considered ancillary but still important to grasp the status of any organism through blood serum analysis. Due to its wide chemical diversity, modern metabolomics analysis of serum is still struggling to provide a complete and comprehensive picture of the polar metabolome, due to the limitations of each specific analytical method. In this study, two metabolomics-based analytical methods using the most successful techniques for polar compounds separation in human serum samples, namely hydrophilic interaction liquid chromatography (HILIC) and capillary electrophoresis (CE), are evaluated, both coupled to a high-resolution time-of-flight mass spectrometer via electrospray ionization (ESI-Q-TOF-MS). The performance of the two methods have been compared using five terms of comparison, three of which are specific to metabolomics, such as (1) compounds' detectability (2) Pezzatti score (Pezzatti et al. 2018), (3) intra-day precision (repeatability), (4) ease of automatic analysis of the data (through a common deconvolution alignment and extrapolation software, MS-DIAL, and (5) time & cost analysis. From this study, HILIC-MS proved to be a better tool for polar metabolome analysis, while CE-MS helped identify some interesting variables that gave it interest in completing metabolome coverage in metabolomics studies. Finally, in this framework, MS-DIAL demonstrates for the first time its ability to process CE data for metabolomics, although it is not designed for it.

Non-aqueous capillary electrophoresis-time of flight mass spectrometry method to determine emerging mycotoxins.

Enniatins (ENN) and beauvericin (BEA) are emerging mycotoxins that have been traditionally determined by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). However, to the best of our knowledge, no analytical methods based on capillary electrophoresis (CE)-MS/MS have been reported so far. Due to their non-polar nature, in this work, a non-aqueous CE (NACE) method coupled to quadrupole time-of-flight-MS is proposed for the first time to identify and quantify these mycotoxins. Determination was achieved in 4 min under optimum conditions: 40 mM ammonium acetate in 80:20 (v/v) acetonitrile-methanol (buffer), 30 kV (voltage), 80 cm (capillary length), 20 °C (capillary temperature) and 50 mbar × 30 s (injection). Higher selectivity can be achieved when compared with LC due to the formation of exclusive CE adducts such as [M + CH3CH2NH3]+. "All Ions" acquisition mode was selected as it allows the quantification of the usual ENNs, as well as the identity confirmation of less common ENNs. The method was validated for wheat samples, obtaining limits of quantification from 4.0 to 8.3 µg/kg depending on the emerging mycotoxin, recovery values higher than 87.4%, and intra- and inter-day precision values (RSDs) lower than 15.1% in all cases. Finally, 29 wheat samples were analyzed, finding 26 samples with concentrations of enniatin B higher than the limit of quantification (7.5-1480 µg/kg), 20 for enniatin B1 (5.2-550 µg/kg), 7 for enniatin A (10-55 µg/kg), 4 for enniatin A1 (12.6-77 µg/kg) and 5 for BEA (9.2-16.4 µg/kg). Moreover, two other ENNs were tentatively identified.

Identity confirmation of anthocyanins in berries by LC-DAD-IM-QTOFMS.

Rugged analytical methods for the screening and identity confirmation of anthocyanins require a dedicated sample preparation, chromatographic setup, and the reliable generation of multiple identification points to confirm identity against the wide range of phenolic compounds typically present in food, beverage, and plant material samples. To this end, combinations of spectroscopic and mass spectrometric detection are frequently employed for this application to provide higher confidence in the absence of authentic standards. In the present work, low-field drift tube ion mobility (DTIM) separation is evaluated for this task using a LC-DAD-DTIM-QTOFMS method. DTIM-MS allows accurate determination of collision cross sections (DT CCS) for all analysed compounds as well as a precise alignment tool for reconciling fragment and precursor ions in data independent acquisition mode. The presented approach thereby allows for an anthocyanin screening method taking true advantage of all dimensions of the analytical platform: relative retention (RPLC), UV/VIS absorption spectrum, accurate mass, DT CCSN2 , and confirmed high-resolution fragment ions. From the analysis of authentic standards and several berry samples primarily from the Vaccinium genus, Level 1 confirmation data for six anthocyanins from the cyanidin family, and Level 2 confirmation for a further 29 anthocyanins confirmed in berry samples is provided. The method and accompanying dataset provided as part of this work provides a means to develop anthocyanin screening methods using the ion mobility dimension as an additional alignment and filtering parameter in data independent analysis acquisition across any LC-IM-MS platform.

Selective ultrasound-enhanced enzymatic hydrolysis of oleuropein to its aglycon in olive (Olea europaea L.) leaf extracts.

Hydrolysis of oleuropein, the main phenol in olive (Olea europaea L.) leaf extracts, to oleuropein aglycon and other subsequent products in the hydrolytic pathway can be catalyzed by different enzymes. Three of the most used hydrolases were assayed to catalyze the process, and ß-glucosidase from Aspergillus niger was selected. Acceleration of the enzymatic hydrolysis by ultrasound (US) was studied using a Box-Behnken design (duty cycle, amplitude, cycle time) and an oleuropein standard, and the optimum US conditions for achieving maximum yield of oleuropein aglycon were 0.5s/s duty cycle, 50% amplitude and 45s cycle. The method was applied to obtain oleuropein aglycon from commercial and laboratory extracts from olive leaves, which may have a pharmacological use as deduced by its healthy properties. The kinetics of the US-assisted enzymatic hydrolysis was monitored by analysis of the target compounds using liquid chromatography-tandem mass spectrometry.