Occurrence and risk assessment of pesticides and their transformation products related to olive groves in surface waters of the Guadalquivir river basin.

Pesticides are considered one of the main sources of contamination of surface waters, especially in rural areas highly influenced by traditional agricultural practices. The objective of this work was to evaluate the impact caused by pesticides and their transformation products (TPs) related to olive groves in surface waters with strong agricultural pressure. 11 streams were monitored during four sampling campaigns over 2 years. A solid-phase extraction, followed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) analysis was used in the quantitative target approach, with more than 70 validated compounds. Target method was combined with a suspect screening strategy involving more than 500 pesticides and TPs, using ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) to identify additional pesticides and TPs out of the scope of analysis. A total of 43 different compounds were detected with the target method. The herbicide MCPA was present in all samples and at the highest concentration (1260 ng L-1), followed by the fungicide carbendazim (1110 ng L-1), and the herbicide chlorotoluron (706 ng L-1). The suspect screening strategy revealed the presence of 7 compounds out of the target analysis (1 pesticide and 6 TPs). 6 analytes were confirmed with the analytical standards. Semi-quantification results revealed that TPs exhibited higher concentrations than their corresponding parent compounds, indicating higher persistency. Some small streams showed a comparable number of pesticides and concentrations to the most polluted large river. The determined pesticide and TPs concentrations represented an estimated environmental hazard in almost all sampling sites under study. This work underscores the importance of including pesticide TPs and small streams impacted by extensive agricultural activities in water quality monitoring programs.

Liquid chromatography-dielectric barrier discharge ionization mass spectrometry for the analysis of neutral lipids of archaeological interest.

Dielectric barrier discharge ionization has gained attention in the last few years due to its versatility and the vast array of molecules that can be ionized. In this study, we report on the assessment of liquid chromatography coupled to dielectric barrier discharge ionization with mass spectrometry for neutral lipid analysis. A set of different neutral lipid subclasses (triacylglycerides, diacylglycerides, and sterols) were selected for the study. The main species detected from our ionization source were [M-H2 O+H]+ , [M+H]+ or [M-R-H2 O+H]+ , attributed to sterol dehydration, protonation or the fragmentation of an acyl chain accompanied by a water loss of the glycerolipids, respectively. In terms of sensitivity, the dielectric barrier discharge displayed overall improved abundances and comparable or better limits of quantitation than atmospheric pressure chemical ionization for both acylglycerols and sterols. As a case study, different archaeological samples with variable content in neutral lipids, particularly triacylglycerides, were studied. The identification was carried out by combining accurate mass and the tentative formula associated with the exact mass, retention time matching with standards, and additional structural information from in-source fragmentation. The high degree of unsaturation and the presence of sterols revealed the potential vegetal origin of the material stored in the analyzed samples.

Ionization of semi-fluorinated n-alkanes in controlled atmosphere using flexible micro-tube plasma (FµTP) ionization source with square- and sine-wave voltage.

Non-thermal plasma-based ionization sources have been widely used and shown excellent soft ionization performance in mass spectrometry. Despite their extensive application, the ionization mechanisms of these sources are of great interest for further exploring their full potential. A controlled atmosphere can provide a clean and controllable ionization environment and is beneficial for studying the ionization mechanism. The plasma source itself also has a significant impact on the ionization mechanism of the analyte, and the voltage waveform is one of the key parameters for controlling the plasma source. In this paper, a miniature flexible micro-tube plasma (FµTP) ionization source was sustained using both square and sine-wave voltage. The ionization processes of typical semi-fluorinated n-alkanes (SFAs) were investigated in the controlled atmosphere filled with 80% N2 and 20% O2. The main mass peaks using both square and sine-wave voltages are found to be [M-mH]+ and [M-mH+nO]+ (m = 1, 3; n = 0, 1, 2). However, for the square-wave voltage, the [M-H+O]+ species are the most abundant while [M-H]+ species are dominant for the sine-wave voltage, showing that the plasma generated with sine-wave voltage is somewhat "softer" than the one with square-wave voltage for SFAs. With the assistance of optical spectroscopy, the plasma developments in one discharge cycle for both voltage waveforms were obtained. Only one discharge can be found in each half cycle for square-wave voltage while several for the sine-wave voltage. These would be responsible for the different ionization behaviors in these two cases. This work provides more insight into the ionization mechanism of SFAs and more understanding of plasma-based soft ionization. In addition, the analytical performance was evaluated to be comparable when using these two voltage generators with a big difference in cost, which will benefit the instrumental development.

Development of a capillary electrophoresis method for the separation of flavonolignans in silymarin complex.

CE method for the baseline separation of structurally similar flavonolignans silybin A, silybin B, isosilybin A, isosilybin B, silychristin, silydianin, and their precursor taxifolin in silymarin complex has been developed and validated. The optimized background electrolyte was 100 mmol/L boric acid (pH 9.0) containing 5 mmol/L heptakis(2,3,6-tri-O-methyl)-ß-CD and 10% (v/v) of methanol. The separation was carried out in an 80.5/72 cm (50 µm id) fused silica capillary at +25 kV with UV detection at 200 nm. Genistein (10 µg/mL) was used as internal standard. The resolution between the diastereomers of silybin and isosilybin was 1.73 and 2.59, respectively. The method was validated for each analyte in a concentration range of 2.5-50 µg/mL. The calibration curves were rectilinear with correlation coefficients ≥0.9972. The method was applied to determine flavonolignans in two dietary supplements containing Silybum marianum extract. The accuracy was evaluated by comparing the results of the CE analyses of the dietary supplements with those of the reference United States Pharmacopeial HPLC method. The unpaired t-test did not show a statistically significant difference between the results of both the proposed CE and the reference method (p > 0.05, n = 3).

Evaluation of a novel controlled-atmosphere flexible microtube plasma soft ionization source for the determination of BTEX in olive oil by headspace-gas chromatography/mass spectrometry.

Although electron impact ionization (EI) remains the standard ionization source for GC-MS, it presents extensive fragmentation as its main limitation. The potential of a novel plasma-based soft ionization source named controlled-atmosphere flexible microtube plasma (CA-FµTP) has been evaluated in this work for the determination of monoaromatic volatile BTEX group (namely benzene, toluene, ethylbenzene, and o-, m- and p-xylenes) in olive oil, based on headspace technique. The obtained results show an attractive advantage over EI due to no fragmentation was observed. A nitrosated ion [M + NO]+ is obtained as the most abundant species. Thus, the BTEX mass spectrum identification can be carried out without major effort. In general, the sensitivity for CA-FµTP was comparable to those obtained by EI, achieving LODs ranged from 0.6 to 1.0 µg kg-1. The potential usefulness of GC-CA-FµTP-MS for the detection of BTEX was demonstrated by analyzing olive oil samples and identifying traces of these compounds in one sample. Therefore, the proposed plasma-based soft ionization is suitable for BTEX analysis in fatty complex matrixes as olive oil.

Worldwide survey of pesticide residues in citrus-flavored soft drinks.

After more than ten years since pesticide residues were detected in citrus-flavored soft drinks, this study reveals that the situation has not changed. A new sensitive multiresidue UHPLC-MS/MS method has been validated for 88 pesticides, which was used to analyze 200 samples manufactured in 67 countries, 80% corresponding to fruit-based soft drinks. The results show that 98% of the samples collected worldwide contained at least one pesticide, and 85% of them contained more than 4 pesticides. 40 out of 88 target compounds were quantified among the screened samples. Europe was the world region with the highest total amount of pesticides, probably due to the higher content of juice concentrate in samples, which may be the main source of the pesticide residues. Nevertheless, residues were also found in samples with no juice, so water quality also plays an important role as the main ingredient of citrus-flavored soft drinks.

Determination of atropine and scopolamine in spinach-based products contaminated with genus Datura by UHPLC-MS/MS.

Datura species are well known because of their high concentration of tropane alkaloids, which has led to poisoning episodes when Datura is accidentally mixed with edible crops. Therefore, the European Union has set a maximum level in cereal-based infant food products of 1 µg kg-1 for atropine and scopolamine. However, the occurrence of these compounds in other commodities has become a global concern. Spinach and derived products can be contaminated with Datura innoxia leaves. In this study, we tested frozen spinachs and spinach-based infant food products. The determination was carried out by UHPLC-MS/MS after applying the QuEChERS method as sample treatment. The LOQs were below 0.016 µg kg-1, achieving satisfactory results in terms of precision, accuracy, and matrix effects. The obtained results (ranging between 0.02 and 8.19 µg kg-1) were close to the maximum level set by the European Union for 24% of the samples tested.

In-line molecularly imprinted polymer solid phase extraction-capillary electrophoresis coupled with tandem mass spectrometry for the determination of patulin in apple-based food.

We present a simple and sensitive method for the determination of patulin at µg·kg-1 level in apple-based products. Our method relies on the application of an in-line molecularly imprinted polymer solid-phase extraction microcartridge in capillary electrophoresis coupled with mass spectrometry. Capillary zone electrophoresis method has been developed and parameters affecting the in-line process have been carefully optimized. Validation parameters were assessed for patulin, giving LOQ of 1 µg·kg-1 and linearity range 1-100 µg·kg-1 with R2 ≥ 0.997. The LOQ was below the maximum content of patulin requested by the European Union in this type of products. The precision of the peak area and the migration time were less than 14.9 and 1.6%, respectively. Patulin has been analyzed in the presence of 5-hydroxymethylfurfural, which is the main interference in this kind of matrix. The method was applied to assay patulin content in various apple-based products.

Stability study of α-bromophenylacetic acid: Does it represent an appropriate model analyte for chiral separations?

The stability of α-bromophenylacetic acid (BPAA) in 50% aqueous methanol solution has been tested. CE in different running buffers was used to separate BPAA from the decomposition reaction products α-hydroxyphenylacetic (mandelic) acid and α-methoxyphenylacetic acid. Suitable CE separation of all three compounds and other product, bromide, was achieved in 60 mmol/L formate buffer (pH 3.0) at -30 kV in 50 µm (i.d.) poly(vinyl alcohol)-coated fused silica capillary (30 cm/24.5 cm) with UV detection at 200 nm. The CE method was applied to determine the reaction order of the decomposition of BPAA (0.47 mmol/L) via nucleophilic substitution in 50% aqueous methanol. The first-order reaction kinetics was confirmed by linear and non-linear regression, giving the rate constants 1.52 × 10-4 ± 2.76 × 10-5 s-1 and 7.89 × 10-5 ± 5.02 × 10-6 s-1, respectively. Additionally, the degradation products were identified by CE coupled to mass spectrometric (MS) detection. The CE-MS experiments carried out in 60 mmol/L formate buffer (pH 3.0) and in 60 mmol/L acetate buffer (pH 5.0) confirmed the results obtained by CE-UV. Furthermore, the stability of BPAA in polar solvents was tested by 1H NMR experiments. Our results provide strong evidence of the instability and fast degradation of BPAA in 50% aqueous methanol indicating that BPAA is not suitable as the model analyte for chiral separations.

Ambient (desorption/ionization) mass spectrometry methods for pesticide testing in food: a review.

Ambient mass spectrometry refers to the family of techniques that allows ions to be generated from condensed phase samples under ambient conditions and then, collected and analysed by mass spectrometry. One of their key advantages relies on their ability to allow the analysis of samples with minimal to no sample workup. This feature maps well to the requirements of food safety testing, in particular, those related to the fast determination of pesticide residues in foods. This review discusses the application of different ambient ionization methods for the qualitative and (semi)quantitative determination of pesticides in foods, with the focus on different specific methods used and their ionization mechanisms. More popular techniques used are those commercially available including desorption electrospray ionization (DESI-MS), direct analysis on real time (DART-MS), paper spray (PS-MS) and low-temperature plasma (LTP-MS). Several applications described with ambient MS have reported limits of quantitation approaching those of reference methods, typically based on LC-MS and generic sample extraction procedures. Some of them have been combined with portable mass spectrometers thus allowing "in situ" analysis. In addition, these techniques have the ability to map surfaces (ambient MS imaging) to unravel the distribution of agrochemicals on crops.

Endogenous Biosynthesis of S-Nitrosoglutathione From Nitro-Fatty Acids in Plants.

Nitro-fatty acids (NO2-FAs) are novel molecules resulting from the interaction of unsaturated fatty acids and nitric oxide (NO) or NO-related molecules. In plants, it has recently been described that NO2-FAs trigger an antioxidant and a defence response against stressful situations. Among the properties of NO2-FAs highlight the ability to release NO therefore modulating specific protein targets through post-translational modifications (NO-PTMs). Thus, based on the capacity of NO2-FAs to act as physiological NO donors and using high-accuracy mass-spectrometric approaches, herein, we show that endogenous nitro-linolenic acid (NO2-Ln) can modulate S-nitrosoglutathione (GSNO) biosynthesis in Arabidopsis. The incubation of NO2-Ln with GSH was analyzed by LC-MS/MS and the in vitro synthesis of GSNO was noted. The in vivo confirmation of this behavior was carried out by incubating Arabidopsis plants with 15N-labeled NO2-Ln throughout the roots, and 15N-labeled GSNO (GS15NO) was detected in the leaves. With the aim to go in depth in the relation of NO2-FA and GSNO in plants, Arabidopsis alkenal reductase mutants (aer mutants) which modulate NO2-FAs levels were used. Our results constitute the first evidence of the modulation of a key NO biological reservoir in plants (GSNO) by these novel NO2-FAs, increasing knowledge about S-nitrosothiols and GSNO-signaling pathways in plants.

Study of Controlled Atmosphere Flexible Microtube Plasma Soft Ionization Mass Spectrometry for Detection of Volatile Organic Compounds as Potential Biomarkers in Saliva for Cancer.

A new soft ionization device for mass spectrometry is presented using the flexible microtube plasma under controlled atmospheric conditions. The controlled atmosphere flexible microtube plasma consists of the plasma source itself connected to a gas chromatograph and a mass spectrometer using a borosilicate glass cross piece. Controlled atmosphere, for example, nitrogen and/or an oxygen mixture, is introduced to the system to create a clean ionization environment. Reproducibility issues are discussed, and solutions are presented manipulating the gas flow in the cross piece. A proof of concept is shown using a ketone mixture introduced to the mass spectrometer to optimize atmospheric conditions. Furthermore, application of the presented device for the sensitive and nonfragmenting ionization of volatile organic biomarkers relevant for cancer is carried out. Sample treatment for human saliva is described, and relevant candidate biomarkers are measured in the saliva matrix, showing a very good ionization efficiency and neglectable matrix effects with limits of detection below 80 ppt.

Quantitative determination of pesticide residues in specific parts of bee specimens by nanoflow liquid chromatography high resolution mass spectrometry.

The presence of pesticide residues in bees is of great interest, given the central role of bees as indicators for environmental assessment. The goal of this article is to propose a method to capture enhanced chemical information for these central environmental indicators. Most of the methods rely on the analysis of pooled samples rather than individual specimens due to practical sample preparation method considerations and limitations in sensitivity. This leads to miss information on the mapping of pesticides and actual amount of pesticide per specimen. In this article, a nanoflow liquid chromatography system coupled to high resolution mass spectrometry (using a hybrid quadrupole-Orbitrap instrument) has been applied for the development of a multiresidue pesticide method for the determination of 162 multiclass pesticides in specific part of honeybee samples (ca. abdomen, head or thorax). The reduced flow rate provided an enhancement in sensitivity and a strong reduction of matrix effects, thus only a quick and simple ultrasound assisted extraction using minute amount of sample was required. Satisfactory results were obtained for all tested analytes with concentration levels detected lower than 0.5 ng g-1 in all cases, thus being acceptable for monitoring purposes. Matrix effect was negligible for 94% of compounds. Extraction recoveries ranged from 70% to 105%, being within SANTE guidelines. Finally, the applicability of the method was demonstrated, by successful application to the analysis of contaminated honeybee samples, extracting useful information from specific bee parts of single specimens, thus, enabling pseudo spatially resolved chemical information.

Determination of Sudan dyes in chili products by micellar electrokinetic chromatography-MS/MS using a volatile surfactant.

A new MEKC-MS/MS method was developed for the determination of four Sudan dyes in chili products. The separation and MS detection conditions were optimized to achieve fast, efficient, selective, and sensitive determination of Sudan I, Sudan II, Sudan III, and Sudan IV dyes. The target compounds were extracted from chili samples with acetonitrile and cleaned by freeze-out. This two-step sample preparation led to excellent extraction efficiency and minimal matrix effect. The analytical performance of the method was very good, with r2 ≥ 0.9914 and limits of quantification lower than 22 µg kg-1. The precision was below 15.7%. The recovery for spiked samples ranged from 84.4 to 99.6%, with relative standard deviations less than 8.0%. For all evaluated samples, the matrix effects did not exceed ± 10%. The applicability of the proposed method was demonstrated with 20 chili products, two of which were found to contain Sudan I and IV residues.

Basin-scale monitoring and risk assessment of emerging contaminants in South American Atlantic coastal lagoons.

Emerging contaminants (ECs) such as pharmaceuticals, personal care products, drugs of abuse and polar pesticides are under particular attention due to their high consumption, frequent detection in the environment and reported ecotoxicological risk. This study investigates the occurrence and distribution of multiclass of ECs in surface waters at basin scale of two Atlantic coastal lagoons of Uruguay, South America. For this purpose, a target screening approach covering up to 362 compounds was employed using nanoflow liquid chromatography - high resolution mass spectrometry (nanoLC/HRMS). 56 compounds were identified including five banned pesticides in the European Union: atrazine, carbendazim, chlorpyrifos ethyl, diazinon, and ethion. Pharmaceuticals, hormones and drugs of abuse showed maximum detection frequencies and concentrations downstream cities. The highest occurrence of pesticides was found in lagoons and streams with neighboring agricultural activity. ECs were also found in coastal sea. Environmental risk assessment revealed that the hormones 17α-ethinylestradiol and 17-ß-estradiol showed the highest risk to aquatic organisms in these basins. This study represents the first basin- scale monitoring of ECs in superficial waters encompassing streams, lagoons, and coastal seas in Uruguay, South America.

Detection of multiclass explosives and related compounds in soil and water by liquid chromatography-dielectric barrier discharge ionization-mass spectrometry.

In this work, the multiclass detection of explosives and related compounds has been studied by liquid chromatography-high-resolution mass spectrometry by means of a time-of-flight mass spectrometer (TOFMS) operated in the negative ion mode, using dielectric barrier discharge ionization (DBDI). Reversed-phase high-performance liquid chromatography (HPLC) separation was performed using water-methanol mobile phase without any modifier, although the effect of ammonium acetate was studied. DBD plasma was generated by applying a square wave voltage of 2.5 kV to a 100-mL min-1 He flow. The DBDI probe was adjusted to fit the commercial API source housing so that the HPLC eluent was nebulized and vaporized in the same manner as for atmospheric-pressure chemical ionization (APCI). The ionization process was affected by the temperature of the two nitrogen streams used to vaporize the solvent and the analytes, particularly for RDX and HMX, which are thermolabile compounds. The best approach in terms of sensitivity for all the studied compounds was the use of a gradient of temperatures in the ionization source, starting at 225/200 °C (vaporizer/drying gas temp) for nitramines and ending at 350/325 °C for nitroaromatic compounds. High-resolution full-scan spectra of individual selected compounds were recorded by LC-DBDI-TOFMS, and the results were compared to LC-APCI-TOFMS. A better sensitivity (slope of calibration curve) was obtained by DBDI for more than 70% of the studied compounds in both wastewater and soil extracts. Graphical abstract ᅟ.

Critical assessment of two sample treatment methods for multiresidue determination of veterinary drugs in milk by UHPLC-MS/MS.

In this work, two sample treatment procedures have been evaluated for the determination of veterinary drug residues in milk. In order to cover a wide range of polarities, a total of 66 veterinary drugs with log Kow ranging from - 1 to 5 were selected. Two sample cleanup steps, (i) dispersive solid-phase extraction (dSPE) using enhanced matrix removal lipid as sorbent and (ii) solid-phase extraction (in pass-through mode) using Oasis HLB PRiME cartridges, were critically assessed in terms of sample throughput, recovery, matrix effect, cleanliness of extracts, limit of quantification, and repeatability. The veterinary drugs tested (viz. benzimidazoles, cephalosporins, imidazothiazoles, macrolides, NSAIDs, penicillins, quinolones, steroids, sulfonamides, and ß-agonists) were analyzed by ultra-high-performance liquid chromatography tandem mass spectrometry. According to the results, both methods exhibited similar recovery rates between 70 and 120% for most of compounds tested. Matrix effects were satisfactory for both methodologies, although the tolerance to matrix effects was slightly higher with HLB PRiME with nearly negligible matrix effects in most cases. Limits of quantitation were also well below the current maximum residue levels established by the European Union. Notably, sample throughput was higher in the case of HLB PRiME, since this pass-through SPE cleanup approach involved fewer steps than the EMR-Lipid dSPE approach. The results in terms of analysis time, sensitivity, precision, cleanliness of extracts, and matrix effect showed the suitability of both procedures for the monitoring of veterinary drugs residues in milk samples in a single run. Graphical abstract.

Use of a modified QuEChERS method for the determination of mycotoxin residues in edible nuts by nano flow liquid chromatography high resolution mass spectrometry.

A nanoflow liquid chromatography high resolution mass spectrometry method for the quantification of mycotoxins in nuts has been developed. Two strategies based on QuEChERS methodology were evaluated. Thus, EMR-lipid was compared with a conventional mixture of PSA and C18 dispersive solid phase extraction sorbents which have been commonly used in this type of matrices as sample clean-up. The results showed that the use of EMR-lipid reduced more effectively matrix components, achieving a negligible matrix effect for all mycotoxins studied in peanut, pistachio and almond. The proposed method was validated in line with SANTE guidelines using EMR-Lipid as dispersive solid phase extraction sorbent. The lowest concentration level were between 0.05 and 5 µg kg-1, being lower than the maximum levels established by the current legislation. Recovery rates ranged from 75% to 98% was obtained in all sample studied, achieving also satisfactory precision with RSD values lower than 19% in all cases.

Monitoring the degradation of atropine and scopolamine in soil after spiking with naturally contaminated organic millet.

The spread of Datura sp. in European countries influences crop management and implies continuous food safety issues because of tropane alkaloids, atropine and scopolamine, the most relevant natural toxic compounds of this weed. These alkaloids can contaminate cereals to such a level that hampers food/feed related use and diverts batches of contaminated raw materials towards ultimate disposal such as burning. As no unambiguous information has been available on the fate of tropane alkaloids in soils, our study focused on the quantification and follow-up of these toxic residues in a soil experiment where the tropane alkaloids were mixed to the soil in the form of naturally contaminated unhulled millet in 1:40 millet:soil ratio - this approach provides a more realistic scenario compared to standard solution based spiking. To achieve accurate results, soil and millet extraction processes have been validated and a liquid chromatography - mass spectrometry set-up was addressed to provide selective and quantitative analysis. The initial concentration of atropine (75ngg-1) and scopolamine (47ngg-1) in the soil decreased with >90% in 15days and reached a high level of elimination (>97%) in 29days. This observation opens an option for the use of tropane contaminated millet or millet waste other than burning, as these toxic alkaloids can be significantly degraded in the soil system. On the other hand, the persistence of intact tropane alkaloids in soils might be questioned to the extent that calls the attention to the (re)assignment of their supposed allelopathic effects.

Multi-residue pesticide analysis in virgin olive oil by nanoflow liquid chromatography high resolution mass spectrometry.

In this article, a nanoflow liquid chromatography system coupled to high resolution mass spectrometry (nanoflow LC/ESI Q-Orbitrap-MS) has been applied for the development of a multiresidue pesticide method for the determination of 162 multiclass pesticides in olive oil samples. Due to the relatively high lipid content of the raw QuEChERS acetonitrile extracts obtained from this type of fatty vegetable samples, a dispersive solid phase extraction (dSPE) sorbent proposed to retain both fatty acids and triglycerides, namely Enhanced Matrix Removal-Lipid (EMR-Lipid) has been implemented as additional cleanup step. The analytical performances of the proposed method were evaluated,achieving recoveries in the range 75-119% with relative standard deviations lower than 19% (n = 6). The dSPE sorbent allowed the removal of most coextracted interferences without a significant loss of analytes. Matrix effects were also evaluated, showing a negligible effect for most of the compounds tested, when a dilution factor of 50 was applied. Notably, despite the use of relatively high dilution factors (e.g. 1:50) to minimize matrix effects, the lowest concentration levels detected with this method - in the low µg kg-1 range - are well below the corresponding maximum residue levels established by the current European legislation.