Assessment of the occurrence and interaction between pesticides and plastic litter from vineyard plots.

In this research, aged plastic fragments collected from vineyards were characterized in terms of composition, residues of pesticides, and their potential to exchange these compounds with the aquatic media. To this end, we employed the qualitative and quantitative information provided by complementary analytical techniques, including chromatography, organic and inorganic mass spectrometry, infrared spectroscopy and electronic microscopy. Debris of weathered plastics were identified as polypropylene and polyethylene, containing different types of additives, from organic UV stabilizers to inorganic fillers, such as calcium salts. Regardless of polymer type, plastic litter collected from vineyards contained residues of pesticides, and particularly of fungicides, with total concentrations in the range of values from 114 ng g-1 to 76.4 µg g-1. Data obtained under different extraction conditions suggested that a fraction of these compounds was absorbed in aged polymers, penetrating inside the material. The parallel analysis of plastic litter and vineyard soils reflected higher pesticide residues in the former matrix. Furthermore, several fungicides, considered as labile in vineyard soils (i.e. zoxamide and folpet), were those showing the highest levels in plastic litter. Simulated sorption-desorption studies, with plastic debris in contact with surface water, demonstrated the higher affinity of aged materials by moderately polar pesticides than their new counterparts. For the first time, the manuscript highlights the presence of plastic litter in vineyards soils, reflecting the accumulation of several fungicides in this matrix, in some cases, with a different stability pattern to that observed in the soil from same vineyards.

Supercritical fluid chromatography time-of-flight mass spectrometry enantiomeric determination of basic drugs in sewage samples.

Many pharmacologically active compounds are chiral species, and their therapeutic or toxicological effects might differ between isomers. Herein, we develop a fast and sensitive chiral analysis methodology for the determination of eight pharmaceuticals, considered as emerging environmental pollutants and belonging to two different chemical classes, in wastewater and sludge samples. Compounds were separated using supercritical fluid chromatography (SFC) combined with time-of-flight mass spectrometry (TOF-MS) detection. The stationary phase, the modifier and the additive combined with supercritical carbon dioxide (CO2), in the SFC mobile phase, played a major effect in the enantiomeric resolution of selected compounds. Moreover, the composition of the mobile phase affected their ionization efficiency in the electrospray ionization source. Methanol (MeOH), containing a 0.1% of ammonia, was used as CO2 modifier for the separation of compounds in a polysaccharide-type column. Total analysis time was 15.5 min, achieving resolution factors between 1.03 and 2.49 for the eight pairs of enantiomers. In combination with mixed-mode solid-phase extraction and matrix solid-phase dispersion protocols, compounds were determined in wastewater and sludge samples, with limits of quantification in the range of 0.010-0.020 µg L-1 and 3.7-11.1 ng g-1, for aqueous and solid samples, respectively. The amine-type drugs (tramadol, propranolol and venlafaxine) were mostly found in wastewater samples, whilst azolic antimycotics were mainly quantified in sludge. The first group of compounds showed enantiomeric fractions significantly different to those existing in the commercial counterpart pharmaceuticals.

Assessment of direct analysis in real time accurate mass spectrometry for the determination of triclosan in complex matrices.

In this work, the applicability of direct analysis in real time coupled to accurate mass spectrometry (DART-MS) to the quantitative determination of triclosan (TCS) in samples with increasing complexity, from personal care products to extracts from sewage, is investigated. In the first term, DART-MS spectra of TCS as free phenol and as derivatized species are characterized; thereafter, the effects of several instrumental variables in the detectability of TCS (i.e., temperature, solvent, and compound holder) are discussed. Under final selected conditions, TCS was determined from its [M-H]- ions, without need of derivatization, attaining an instrumental limit of quantification of 5 ng mL-1, with a linear response range up to 1000 ng mL-1. Complex matrices, such as solid-phase extracts obtained from environmental water samples, moderately inhibited the ionization efficiency of TCS, with signal attenuation percentages in the range of 6 to 57%, depending on the sample type and on the concentration factor provided by the SPE procedure. The accuracy of results obtained by DART-MS was evaluated using liquid chromatography (LC) with MS detection; in both cases, a time-of-flight (TOF) MS instrument was employed for the selective determination of the [M-H]- ions of TCS (m/z values 286.9439 and 288.9410) using a mass window of 20 ppm. DART-MS did not only provide enough sensitivity to detect the presence of TCS in environmental samples (raw and treated wastewater as well as freeze-dried sludge), but also measured concentrations matched those determined by LC-ESI-TOF-MS, with only slightly higher standard deviations. During analysis of personal care products, containing much higher concentrations of TCS in a less complex matrix, both techniques were equivalent in terms of accuracy and precision. Graphical abstract.

Portable dehumidifiers condensed water: A novel matrix for the screening of semi-volatile compounds in indoor air.

The comprehensive identification of organic species existing in indoor environments is a key issue to understand their impact in human health. This study proposes the analysis of condensed water samples, collected with portable dehumidifiers, to characterize semi-volatile compounds in the gas phase of confined areas. Water samples are concentrated by solid-phase extraction (SPE). The obtained extracts are analysed by gas chromatography (GC) time-of-flight mass spectrometry (TOF-MS), following a non-target screening data mining approach. In first term, spectra of deconvoluted compounds are compared with those in NIST low resolution library; thereafter, tentative identifications are verified using an in-house database of accurate electron ionization (EI) MS spectra. Chromatographic (retention index) and spectral data are combined for unambiguous species identification. The potential of condensed water samples to reflect changes in the composition of indoor atmospheres, the match between data obtained using different dehumidifiers, and the relative concentration efficiency of condensed water compared to that attained by active sampling of moderate air volumes are discussed. A total of 141 semi-volatile compounds were identified (98 confirmed against authentic standards) in a set of 21 samples obtained from different homes and working places. This list contains more than 40 fragrances (including several potential allergens), solvents and intermediates in the production of polymeric materials, plasticizers and flame retardants.

Evaluation of supercritical fluid chromatography accurate mass spectrometry for neonicotinoid compounds determination in wine samples.

The suitability of supercritical fluid chromatography, coupled to accurate mass spectrometry (SFC-MS), for the determination of seven commercial neonicotinoid pesticides and one transformation product in wine samples has been investigated. Thorough optimization of the different parameters (column, modifier, back-flush pressure, make up, etc.) affecting the SFC-MS selectivity and sensitivity was carried out. Under final conditions, a 2 mL volume of either red or white wine was extracted by SPE and analysed using external standard calibration achieving limits of quantification from 1 to 11 ng mL-1. Global recoveries ranged between 63 and 118%, depending on the compound and the spiked amount. When compared to UPLC performance, SFC resulted in a better separation of compounds, narrower peaks, comparable sensitivity and significantly lower matrix effects. The developed method allowed the quantification of imidacloprid in around half of the 25 commercial wine samples processed, all of them proceeding from grapes cultivated in year 2018 in the Northwest of Spain, with a maximum concentration of 33 ng mL-1. Acetamiprid was also detected in some white wine samples.