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This work presents an optimized gas chromatography–electron ionization–high-resolution mass spectrometry (GC-EI-HRMS) screening method. Different method parameters affecting data processing with the Agilent Unknowns Analysis SureMass deconvolution software were optimized in order to achieve the best compromise between false positives and false negatives. To this end, an accurate-mass library of 26 model compounds was created. Then, five replicates of mussel extracts were spiked with a mixture of these 26 compounds at two concentration levels (10 and 100 ng/g dry weight in mussel, 50 and 500 ng/mL in extract) and injected in the GC-EI-HRMS system. The results of these experiments showed that accurate mass tolerance and pure weight factor (combination of reverse-forward library search) are the most critical factors. The validation of the developed method afforded screening detection limits in the 2.5–5 ng range for passive sampler extracts and 1–2 ng/g for mussel sample extracts, and limits of quantification in the 0.6–3.2 ng and 0.1–1.8 ng/g range, for the same type of samples, respectively, for 17 model analytes. Once the method was optimized, an accurate-mass HRMS library, containing retention indexes, with ca. 355 spectra of derivatized and non-derivatized compounds was generated. This library (freely available at https://doi.org/10.5281/zenodo.5647960), together with a modified Agilent Pesticides Library of over 800 compounds, was applied to the screening of passive samplers, both of polydimethylsiloxane and polar chemical integrative samplers (POCIS), and mussel samples collected in Galicia (NW Spain), where a total of 75 chemicals could be identified. [ABSTRACT FROM AUTHOR]

Garlic is one of the most used seasonings in the world whose beneficial health effects, mainly ascribed to organosulfur compounds, are shared with the rest of the Allium family. The fact that many of these compounds are volatile makes the evaluation of the volatile profile of garlic interesting. For this purpose, three garlic varieties- White, Purple, and Chinese-cultivated in the South of Spain were analyzed by a method based on a headspace (HS) device coupled to a gas chromatograph and mass detector (HS-GC/MS). The main temperatures in the HS were optimized to achieve the highest concentration of volatiles. A total number of 45 volatiles were tentatively identified (among them 17 were identified for the first time in garlic); then, all were classified, also for the first time, and their relative concentration in three garlic varieties was used to evaluate differences among them and to study their profiles according to the heating time. Chinese garlic was found to be the richest variety in sulfur volatiles, while the three varieties presented a similar trend under preset heating times allowing differentiation between varieties and heating time using principal component analysis. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The existence of pharmaceuticals and illicit drugs (PIDs) in environmental waters has led many analytical chemists to develop screening methods for monitoring purposes. Water samples can contain a huge number of possible contaminants, commonly at low concentrations, which makes their detection and identification problematic. Liquid chromatography coupled with high resolution mass spectrometry (LC-HRMS) has proven itself effective in the screening of environmental contaminants. The present work investigates the use of the most popular HRMS instruments, quadrupole time-of-flight and linear trap quadrupole-Orbitrap, from two different laboratories. A suspect screening for PIDs was carried out on wastewater (influent and effluent) and surface water samples from Castellón, Eastern Spain, and Cremona, Northern Italy, incorporating a database of 107 PIDs (including 220 fragment ions). A comparison between the findings of both instruments and of the samples was made which highlights the advantages and drawbacks of the strategies applied in each case. In total, 28 compounds were detected and/or identified by either/both instruments with irbesartan, valsartan, benzoylecgonine and caffeine being the most commonly found compounds across all samples. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In the present work, the analysis of seven fullerenes (C and C fullerenes and five functionalised fullerenes) has been performed in river samples collected in the vicinities of Barcelona (Catalonia, NE of Spain). The results of 48 samples (25 river waters, 12 river sediments and 11 wastewater effluents) are presented. Extracts of river water, river sediments and wastewater effluents were analysed by liquid chromatography (LC), using a pyrenylpropyl group bonded silica based column, coupled to a high-resolution mass spectrometer (HRMS), using a dual ion source, atmospheric pressure photoionisation/atmospheric pressure chemical ionisation source (APPI/APCI). The novel methodology presents good chromatographic separation, excellent selectivity and instrumental limits of quantification (ILOQ) in the femtogram order. Method limits of quantification (MLOQ) ranged from 2.9 to 17 pg/l and from 3.2 to 31 pg/l in surface waters and wastewaters, respectively. In wastewater effluents, the sums of C and C ranged from 0.5 to 9.3 ng/l. In surface waters, C fullerene was the most ubiquitous compound, being detected in 100 % of the samples in concentrations from 31 pg/l to 4.5 ng/l, while C concentrations ranged from less than the method limits of detection (MLOD) to 1.5 ng/l. The presence of fullerenes in both the large particulate (diameter Ø > 450 nm) and the colloidal ( Ø < 450 nm) fractions of surface waters should be noticed. In sediments, the concentrations of fullerenes were between the MLOD and 34.4 pg/g. In addition, nanoparticle tracking analysis (NTA) was used for the characterisation of water samples in terms of nanoparticle number concentration and size distribution. As far as our knowledge is concerned, this is the first time that NTA has been used for the characterisation of complex river waters with an environmental focus. [ABSTRACT FROM AUTHOR]