Identification of organic contaminants in water and related matrices using untargeted liquid chromatography high-resolution mass spectrometry screening with MS/MS libraries.

Nontargeted and suspect screening with liquid chromatography-high resolution mass spectrometry (LC-HRMS) has become an indispensable tool for quality assessment in the aquatic environment - complementary to targeted analysis of organic (micro)contaminants. An LC-HRMS method is presented, suitable for the analysis of a wide variety of water related matrices: surface water, groundwater, wastewater, sediment and sludge, including extracts from passive samplers and on-site solid phase enrichment, while focusing on the data processing aspect of the method. A field study is included to demonstrate the practical application and versatility of the whole process. HRMS/MS data were recorded following LC separation in both (ESI) positive and negative ionization modes using data dependent as well as data independent acquisition. Two vendor (Agilent's Personal Compound Database and Library and from National Institute of Standards and Technology) and one open (MassBank/EU) tandem mass spectral libraries were utilized for the identification of compounds via mass spectral match. The development of a novel software tool for parsing, grouping and reduction of MS/MS features in data files converted to mascot generic format (MGF) helped to substantially decrease the amount of time and effort needed for MS library search. While applying the method, in the course of the entire field study, 18771 detections (from 870 individual compounds) in total were recorded in 275 samples, resulting in 68.3 identified compounds per sample, on average. Among the top ten most frequently detected contaminants across all samples and sample types were pharmaceutical compounds carbamazepine, 4-acetamidoantipyrine, 4-formylaminoantipyrine, tramadol, lamotrigine and phenazone and industrial contaminants toluene-2-sulfonamide, tolytriazole, tris(2-butoxyethyl) phosphate and benzotriazole. Exploratory data analysis methods and tools enabled us to discover organic pollutant occurrence patterns within the comprehensive sets of qualitative data collected from various projects between the years 2018-2023. The results may be used as valuable inputs for future water quality monitoring programs.

The NORMAN Suspect List Exchange (NORMAN-SLE): facilitating European and worldwide collaboration on suspect screening in high resolution mass spectrometry.

Background: The NORMAN Association (https://www.norman-network.com/) initiated the NORMAN Suspect List Exchange (NORMAN-SLE; https://www.norman-network.com/nds/SLE/) in 2015, following the NORMAN collaborative trial on non-target screening of environmental water samples by mass spectrometry. Since then, this exchange of information on chemicals that are expected to occur in the environment, along with the accompanying expert knowledge and references, has become a valuable knowledge base for "suspect screening" lists. The NORMAN-SLE now serves as a FAIR (Findable, Accessible, Interoperable, Reusable) chemical information resource worldwide. Results: The NORMAN-SLE contains 99 separate suspect list collections (as of May 2022) from over 70 contributors around the world, totalling over 100,000 unique substances. The substance classes include per- and polyfluoroalkyl substances (PFAS), pharmaceuticals, pesticides, natural toxins, high production volume substances covered under the European REACH regulation (EC: 1272/2008), priority contaminants of emerging concern (CECs) and regulatory lists from NORMAN partners. Several lists focus on transformation products (TPs) and complex features detected in the environment with various levels of provenance and structural information. Each list is available for separate download. The merged, curated collection is also available as the NORMAN Substance Database (NORMAN SusDat). Both the NORMAN-SLE and NORMAN SusDat are integrated within the NORMAN Database System (NDS). The individual NORMAN-SLE lists receive digital object identifiers (DOIs) and traceable versioning via a Zenodo community (https://zenodo.org/communities/norman-sle), with a total of > 40,000 unique views, > 50,000 unique downloads and 40 citations (May 2022). NORMAN-SLE content is progressively integrated into large open chemical databases such as PubChem (https://pubchem.ncbi.nlm.nih.gov/) and the US EPA's CompTox Chemicals Dashboard (https://comptox.epa.gov/dashboard/), enabling further access to these lists, along with the additional functionality and calculated properties these resources offer. PubChem has also integrated significant annotation content from the NORMAN-SLE, including a classification browser (https://pubchem.ncbi.nlm.nih.gov/classification/#hid=101). Conclusions: The NORMAN-SLE offers a specialized service for hosting suspect screening lists of relevance for the environmental community in an open, FAIR manner that allows integration with other major chemical resources. These efforts foster the exchange of information between scientists and regulators, supporting the paradigm shift to the "one substance, one assessment" approach. New submissions are welcome via the contacts provided on the NORMAN-SLE website (https://www.norman-network.com/nds/SLE/). Supplementary Information: The online version contains supplementary material available at 10.1186/s12302-022-00680-6.

Simultaneous focused ultrasound solid-liquid extraction and dispersive solid-phase extraction clean-up for gas chromatography-tandem mass spectrometry determination of polycyclic aromatic hydrocarbons in crustacean gammarids meeting the requirements of the European Union Water Framework Directive.

The study presents the development and validation of a method for the determination of seven priority polycyclic aromatic hydrocarbons (PAHs, including fluoranthene and benzo[a]pyrene, for which the EU has set environmental quality standards, EQS, for biota) in gammarid samples combining focused ultrasound solid-liquid extraction and dispersive solid-phase extraction clean-up in one step followed by gas chromatography-triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS). The method is designed to analyse small about 100 mg dry weight (dw) samples obtained after lyophilisation of 500 mg wet weight (ww) samples. The sample preparation procedure is simple, environment friendly (method was classified as "an excellent green analysis" according to the analytical Eco-Scale assessment), non-laborious and low-cost and, apart from the sample extract concentration step, is quick. Thorough disintegration of the gammarids is achieved by a combination of sonication and the addition of granular anhydrous Na2SO4 to the gammarid suspension, thus avoiding the need to grind the sample prior to analysis. The QqQ-MS/MS detector, thanks to its excellent selectivity and sensitivity, allows to meet the EQS requirements for PAHs in biota with a good margin (limits of quantification in the range of 0.12 and 0.56 ng g‒1 ww). The method has been successfully validated (in terms of linearity, method limits, precision, trueness, robustness, measurement uncertainty and comparative analysis of real samples), and has been shown to be suitable for monitoring and evaluating the PAHs contamination in surface water biota.

Inhibition of immune-mediated concanavalin a-induced liver damage by free-radical scavengers.

BACKGROUND/AIMS: The aims of the present study were to elucidate whether oxidative stress has a role in Con A-induced hepatitis and to examine if antioxidants may protect against liver damage in this model. METHODS: Hepatitis was induced in Balb/c mice by administration of Con A (18 mg/kg) to the tail vein. Liver enzymes and histology were determined 24 h after Con A injection. Tumor necrosis factor alpha (TNFalpha) and interleukin-10 (IL-10) levels were assayed 2 h after Con A injection. Hepatic malondialdehyde levels were measured at 1, 3, 8, 12, 18, and 24 h after Con A injection in order to examine the timing of free-radicals formation. Nuclear factor kappa B (NF-kappabeta) activation was determined by electrophoresis mobility shift assay (EMSA) 1 and 2 h after Con A injection. In separate experiments, mice were pretreated with either dimethylsulfoxide or dimethylthiourea before Con A inoculation. The antioxidant and NF-kappabeta inhibitor pyrrolidine dithiocarbamate (PDTC) was used as positive control. RESULTS: Hepatic malondialdehyde levels increased 12, 18, and 24 h after Con A inoculation but not earlier. Serum levels of liver enzymes and TNFalpha, hepatic malondialdehyde, and protein carbonyls and the histologic necroinflammatory score were significantly reduced in the antioxidants-treated mice, while IL-10 levels were increased. Dimethylsulfoxide, dimethylthiourea, and PDTC inhibited oxidative stress, but only PDTC inhibited Con A-induced NF-kappaB activation. CONCLUSIONS: Reactive oxygen species play a role in immune-mediated Con A-induced hepatitis probably secondary to immune-mediated liver damage. Scavenging of reactive oxygen species by antioxidants prevents hepatitis independently of NF-kappaB inhibition and may be a new therapeutic target in this experimental model.

Comparison of negative chemical ionization and electron impact ionization in gas chromatography-mass spectrometry of endocrine disrupting pesticides.

The study of pesticide residues belonging to endocrine disrupting chemicals (EDCs) (23 analytes of different chemical classes--organochlorines, organophosphates, pyrethroids, dicarboximides, phtalamides, dinitroanilines, pyrazole, triazinone) in apple matrix with conventional capillary GC-NCI-MS (with methane as reagent gas) in comparison to EI ionization is presented. For sample preparation QuEChERS method was applied. The lowest calibration levels (LCLs) for all pesticides were determined in both modes. Calibration in the NCI mode was performed at the concentration levels from 0.1 to 500 microg kg(-1) (R(2) > 0.999) and for EI in the range from 5 to 500 microg kg(-1) (R(2) > 0.99). From LCLs the instrumental limits of detection (LODs) and quantification (LOQs) were calculated. Chemometric study of pesticide signals in two MS modes was performed. Repeatability of all measurements, expressed by the relative standard deviations of absolute peak areas was better than 10% for the majority of compounds. Significantly lower values were obtained for the NCI mode.

Fast gas chromatography for pesticide residues analysis using analyte protectants.

Fast GC-MS with narrow-bore columns combined with effective sample preparation technique (QuEChERS method) was used for evaluation of various calibration approaches in pesticide residues analysis. In order to compare the performance of analyte protectants (APs) with matrix-matched standards calibration curves of selected pesticides were searched in terms of linearity of responses, repeatability of measurements and reached limit of quantifications utilizing the following calibration standards in the concentration range 1-500 ng mL(-1)(the equivalent sample concentration 1-500 microg kg(-1)): in neat solvent (acetonitrile) with/without addition of APs, matrix-matched standards with/without addition of APs. For APs results are in a good agreement with matrix-matched standards. To evaluate errors of determination of concentration synthetic samples at concentration level of pesticides 50 ng mL(-1) (50 microg kg(-1)) were analyzed and quantified using the above given standards. For less troublesome pesticides very good estimation of concentration was obtained utilizing APs, while for more troublesome pesticides such as methidathion, malathion, phosalone and deltamethrin significant overestimation reaching up to 80% occurred. According to presented results APs can be advantegously used for "easy" pesticides determination. For "difficult" pesticides an alternative calibration approach is required for samples potentially violating MRLs. An example of real sample measurement is shown. In this paper also the use of internal standards (triphenylphosphate (TPP) and heptachlor (HEPT)) for peak areas normalization is discussed in terms of repeatability of measurements and quantitative data obtained. TPP normalization provided slightly better results than the use of absolute peak areas measurements on the contrary to HEPT.

Possibilities and limitations of fast GC with narrow-bore columns.

In this work, two narrow-bore capillary columns with different internal diameters (I.D.) 0.15 mm (15 m length, 0.15 microm film thickness) and 0.10 mm (10 m length, 0.10 microm film thickness) with the same stationary phase (5% diphenyl 95% dimethylsiloxane), phase ratio and separation power were compared with regard to their advantages, practical limitations and applicability in fast GC on commercially available instrumentation. The column comparison concerns fast GC method development, speed and separation efficiency, the sample transfer into the column utilizing split and splitless inlet, sample capacity, detection (analysing compounds of a wide range of polarities and volatilities--even n-alkanes C16-C28 and selected pesticides) and ruggedness (in the field of ultratrace analysis of pesticide residues in real matrix). Under conditions corresponding to speed/separation efficiency trade-off 0.10 mm I.D. versus 0.15 mm I.D. column provides a speed gain of 1.74, but all other parameters investigated were better for the 0.15 mm I.D. column concerning more efficient sample transfer from inlet to the column using splitless injection, no discrimination with split injection. Better sample capacity (three times higher for the 0.15 mm than for the 0.10 mm I.D. column) resulted in improved ruggedness and simpler fast GC-MS method development.

Possibilities and limitations of quadrupole mass spectrometric detector in fast gas chromatography.

In this work the application and limitations of a common bench top quadrupole mass spectrometer was evaluated for the qualitative and quantitative measurement of n-alkanes and pesticides of a wide range of volatilities and polarities with fast GC separations using 0.15 mm I.D. narrow-bore capillary columns. It was found that the spectra acquisition rate has a great impact on sensitivity (peak areas, peak shapes and S/N ratios). The quality of the obtained spectra is not significantly influenced in the full scan monitoring mode for the fastest scan rates. For quantitative analysis a selected ion monitoring mode is able to acquire the sufficient number of data-points for the proper peak shape reconstruction and good repeatability of peak areas measurements expressed by RSD (< 5%) for all tested dwell times shorter than 75 ms. However, for shorter dwell times, S/N ratio is lower, while peak areas are not influenced.

Search on ruggedness of fast gas chromatography-mass spectrometry in pesticide residues analysis.

In this study, suitability of fast gas chromatography-mass spectrometry (GC-MS) on a narrow-bore column with a programmed temperature vaporizer for the analysis of pesticide residues in non-fatty food was evaluated. The main objectives were ruggedness and stability of chromatographic system with regards to co-extractives injected. The chromatographic matrix induced response enhancement was found to be strongly dependent on the concentration of residues and is reaching up to 700% compared to the pesticides solutions in a neat solvent. However, the responses of pesticides in matrix-matched standards at different concentration levels do not significantly change during 130 injections. Response enhancement/or decrease is influenced by the sample preparation technique. External calibration with matrix-matched calibration standards should, therefore, provide results with good precision also at the concentration level of 0.005 mg kg(-1). Special attention is given to the performance of the chromatographic column and retention gap with regards to peak widths, peak tailing and different sample preparation methods. During approximately 460 matrix sample injections, the performance of the analytical column was acceptable. GC-MS set-up with 0.15 mm i.d. column can be successfully utilized for the pesticide residues analysis.

Practical aspects of splitless injection of semivolatile compounds in fast gas chromatography.

Possibilities and practical aspects of implementation of splitless injection of larger volumes for fast GC purposes utilizing narrow-bore column, hydrogen as carrier gas, fast temperature programming under programmed flow conditions and commercial instrumentation were searched. As a model sample semivolatile compounds of a broad range of volatility and polarity (7 n-alkanes and 19 pesticides) were chosen. Peak shapes, peak broadening and peak areas and its repeatability were evaluated under various experimental set-ups (liner/injection technique combinations). Various factors, such as liner design, injection technique, retention gap length, compound volatility and polarity, the solvent used, initial oven temperature influenced compound focusation and/or maximal injection volume. Combination of analytical column (CP-Sil 13 CB 25 m long, 0.15 mm i.d., film thickness 0.4 microm) with normal-bore retention gap (1 m long, 0.32 mm i.d.) allowed maximal injection volume 8 microl for 4 mm i.d. liner used without any peak distortion when solvent recondensation in the retention gap was employed.