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The performance of a suspect screening method to detect diverse small-molecule trace organic contaminants (TOCs) was systematically evaluated using a set of 39 model compounds. Experiments showed that ionization efficiency, ion transfer parameters, and chromatography could affect the detection of TOCs. As expected, compounds with low ionization yields and poorly retained compounds in chromatographic columns are more difficult to identify in the samples at environmental concentrations. Similarly, TOCs with large deviations from the average mass of the compounds screened were not transmitted efficiently in the mass spectrometer thus negatively affecting their detection. The suspect screening method was validated in terms of recovery and limits of identification of the model compounds using three different types of solid-phase extraction cartridges (reversed phase with polar groups, mixed-mode anion exchange, and mixed mode cation exchange). Experiments showed that more than two-thirds of the model compounds had recoveries >75% with each of the three cartridges, and comparison of limits of identification showed that more than one-half of the model compounds could be identified at concentrations between 6 and 100 ng [L.sup.-1]. However, it was observed that the amount of co-extracted compounds was higher in mixed-mode ion exchangers compared with the reversed-phase cartridge. Application of the suspect screening method using the three different cartridges to surface water samples showed that between 0 to 3% of the positive matches found by the peak identification algorithm were classified as probable structures. Solutions to improve suspect screening of TOCs are proposed and discussed. Key words: contaminants of emerging concern, pesticides, suspect screening, high-resolution mass spectrometry, solid-phase extraction. Nous avons evalue de facon systematique, a l'aide d'un ensemble de 39 composes modeles, la performance d'une methode de detection de divers micropolluants organiques (MPO) a petite molecule dont la presence est suspectee. Nos experiences ont montre que l'efficacite d'ionisation ainsi que les parametres de transfert d'ion et de chromatographie pouvaient avoir une incidence sur la detection des micropolluants organiques. Tel que nous nous y attendions, les composes a faible rendement d'ionisation et ceux qui sont faiblement retenus par les colonnes chromatographiques sont les plus difficiles a identifier dans les echantillons a des concentrations de l'ordre de celles qu'on trouve dans l'environnement. De meme, les MPO presentant des ecarts importants par rapport a la masse moyenne des composes depistes se transmettaient de maniere peu efficace dans le spectrometre de masse, ce qui nuisait ainsi a leur detection. Nous avons valide la methode de detection de contaminants suspectes sur les plans des taux de recuperation et des limites d'identification des composes modeles a l'aide de cartouches d'extraction en phase solide de trois differents types (phase inverse avec groupes polaires, echange d'ions en mode mixte et echange de cations en mode mixte). Nos experiences ont montre que les deux tiers des composes modeles affichaient des taux de recuperation >75 % avec chacune des trois cartouches. De plus, en comparant les limites de detection, nous avons montre que plus de la moitie des composes modeles pouvaient etre identifies a des concentrations entre 6 et 100 ng [L.sup.-1]. Cependant, nous avons observe que la quantite de composes coextraits etait plus elevee avec les cartouches a echange d'ions en mode mixte qu'avec la colonne en phase inverse. En appliquant la methode de detection de contaminants suspectes avec les trois differentes cartouches a des echantillons d'eau de surface, nous avons montre que 0 a 3% des correspondances trouvees a l'aide de l'algorithme d'identification des pics etaient classees a titre de structures probables. Nous proposons et commentons des solutions pour ameliorer la methode de detection de MPO dont la presence est suspectee. [Traduit par la Redaction] Mots-cles : contaminants soulevant de nouvelles preoccupations, pesticides, depistage de contaminants suspectes, spectroscopie de masse a haute resolution, extraction en phase solide., Introduction Despite the progress in environmental analysis since the 20th century, many trace organic contaminants (TOCs) have gone unnoticed in the environment for years because of inadequate methodology. (1) Pharmaceuticals [...]

Abstract: To improve the certainty that a specific small organic molecule has been detected in a given sample by high-resolution mass spectrometry, other techniques that give conclusive evidence about the [...]

Rationale: The COVID‐19 pandemic demonstrated the importance of high‐throughput analysis for public health. Given the importance of surface viral proteins for interactions with healthy tissue, they are targets of interest for mass spectrometry‐based analysis. For that reason, the possibility of detecting and quantifying peptides using a high‐throughput technique, laser diode thermal desorption–triple quadrupole mass spectrometry (LDTD‐QqQMS), was explored. Methods: Two peptides used as models for small peptides (leu‐enkephalin and endomorphin‐2) and four tryptic peptides (GVYYPDK, NIDGYFK, IADYNYK, and QIAPGQTGK) specific to the SARS‐CoV‐2 Spike protein were employed. Target peptides were analyzed individually in the positive mode by LDTD‐QqQMS. Peptides were quantified by internal calibration using selected reaction monitoring transitions in pure solvents and in samples spiked with 20 μg mL−1 of a bovine serum albumin tryptic digest to represent real analysis conditions. Results: Low‐energy fragment ions (b and y ions) as well as high‐energy fragment ions (c and x ions) and some of their corresponding water or ammonia losses were detected in the full mass spectra. Only for the smallest peptides, leu‐enkephalin and endomorphin‐2, were [M + H]+ ions observed. Product ion spectra confirmed that, with the experimental conditions used in the present study, LDTD transfers a considerable amount of energy to the target peptides. Quantitative analysis showed that it was possible to quantify peptides using LDTD‐QqQMS with acceptable calibration curve linearity (R2 > 0.99), precision (RSD < 18.2%), and trueness (bias < 8.3%). Conclusions: This study demonstrated for the first time that linear peptides can be qualitatively and quantitatively analyzed using LDTD‐QqQMS. Limits of quantification and dynamic ranges are still inadequate for clinical applications, but other applications where higher levels of proteins must be detected could be possible with LDTD. Given the high‐throughput capabilities of LDTD‐QqQMS (>15 000 samples in less than 43 h), more studies are needed to improve the sensitivity for peptide analysis of this technique. [ABSTRACT FROM AUTHOR]

Correct identification of a chemical substance in environmental samples based only on accurate mass measurements can be difficult especially for molecules >300 Da. Here is presented the application of spectral accuracy, a tool for the comparison of isotope patterns toward molecular formula generation, as a complementary technique to assist in the identification process of organic micropollutants and their transformation products in surface water. A set of nine common contaminants (five antibiotics, an herbicide, a beta-blocker, an antidepressant, and an antineoplastic) frequently found in surface water were spiked in methanol and surface water extracts at two different concentrations (80 and 300 μg L-1). They were then injected into three different mass analyzers (triple quadrupole, quadrupole-time-of-fight, and quadrupole-orbitrap) to study the impact of matrix composition, analyte concentration, and mass resolution on the correct identification of molecular formulas using spectral accuracy. High spectral accuracy and ranking of the correct molecular formula were in many cases compound-specific due principally to conditions affecting signal intensity such as matrix effects and concentration. However, in general, results showed that higher concentrations and higher resolutions favored ranking the correct formula in the top 10. Using spectral accuracy and mass accuracy it was possible to reduce the number of possible molecular formulas for organic compounds of relative high molecular mass (e.g., between 400 and 900 Da) to less than 10 and in some cases, it was possible to unambiguously assign one specific molecular formula to an experimental isotopic pattern. This study confirmed that spectral accuracy can be used as a complementary diagnostic technique to improve confidence levels for the identification of organic contaminants under environmental conditions. [ABSTRACT FROM AUTHOR]

In this study, photodegradation experiments simulating the exposure conditions of sunlight on the commonly detected in surface and wastewater contaminants atorvastatin (ATV), bezafibrate (BEZ), oxybenzone (OXZ), and tris(2-butoxyethyl)phosphate (TBEP) were conducted as the fate of these compounds and their transformation products (TPs) was followed. Then a nontargeted analysis was carried out on an urban river to confirm the environmental occurrence of the TPs after which the ECOSAR software was used to generate predicted effect levels of toxicity of the detected TPs on aquatic organisms. Five TPs of ATV were tentatively identified including two stable ones at the end of the experiment: ATV_TP557a and ATV_TP575, that were the product of hydroxylation. Complete degradation of OXZ was observed in the experiment with no significant TP identified. BEZ remained stable and largely undegraded at the end of the exposure. Five TPs of TBEP were found including four that were stable at the end of the experiment: TBEP_TP413, TBEP_TP415, TBEP_TP429, and TBEP_TP343. In the nontargeted analysis, ATV_TP557b, a positional isomer of ATV_TP557a, ATV_TP575 and the 5 TPs of TBEP were tentatively identified. The predicted concentration for effect levels were lower for ATV_TP557b compared to ATV indicating the TP is potentially more toxic than the parent compound. All the TPs of TBEP showed lower predicted toxicity toward aquatic organisms than their parent compound. These results highlight the importance of conducting complete workflows from laboratory experiments, followed by nontargeted analysis to confirm environmental occurrence to end with predicted toxicity to better communicate concern of the newfound TPs to monitoring programs. [Display omitted] • Knowledge is lacking on the fate of most organic contaminants in the environment. • Photolysis plays a key role in the generation of transformation products. • Laboratory-controlled studies can help identify transformation products. • Stable transformation products were identified for contaminants of concern. • A transformation product showed higher predicted toxicity than the parent compound. [ABSTRACT FROM AUTHOR]