Simultaneous quantitative determination,identification and qualitative screening of pesticides in fruits and vegetables using LC-Q-Orbitrap™-MS

A method based on QuEChERS extraction and LC-quadrupole-Orbitrap? MS detection was established utilising an improved fully non-targeted way of data acquisition with and without fragmentation. A full-scan acquisition event without fragmentation (resolving power 70 000) was followed by five consecutive fragmentation events (variable data independent acquisition – vDIA; resolving power 35 000) where all ions from the full-scan range are fragmented. Compared with fragmentation in a single event (all-ion fragmentation – AIF), this improves both selectivity and sensitivity for the fragment ions, which is beneficial for screening performance and identification capability. The method was validated, using the data from the same measurements, for two types of analysis: quantitation/identification and qualitative screening. The quantitative validation, performed according to the guidelines in SANCO/12571/2013, tested the performance of the method for 184 compounds in lettuce and orange at two spiking levels: 10 and 50 ng g^?1. The validation showed that the vast majority of the compounds met the criteria for trueness and precision set in the SANCO guidance document. In the qualitative validation the same 184 compounds were used to test the untargeted screening capabilities of the method. In this validation the compounds were spiked at three levels into 11 different fruit and vegetable matrices, which were measured twice on separate days. Taking all data from the qualitative validation together, an overall detection rate of 92% was achieved at the 10 ng g^?1 level, increasing to 98% at 200 ng g^?1. A screening detection limit (as defined in the SANCO guidelines) of 10 ng g^?1 could be achieved for 134 compounds. For 39 and two pesticides the SDL was 50 and 200 ng g^?1, respectively. For the other nine compounds no SDL could be established. The identification (ion ratio) criteria as recommended in the SANCO document could be met for 93% of the detected pesticide/matrix/concentration combinations. The outcome of both validations shows that the described method can be used to combine quantitative analysis and the identification of frequently detected pesticides (so far typically done using triple quadrupole MS/MS) with a qualitative screening to be used for a wide range of less frequent detected compounds in one measurement.     

Application of GC–MSD and LC–MS/MS for the determination of priority pesticides in baby foods in Serbian market

Babies and small children are especially sensitive population to the exposure to environmental contaminants. Their small mass and developing systems, including brain development may show adverse health effects from even low levels of contamination on a chronic or single dose case. In this paper one extraction method and two chromatographic techniques for the determination of pesticide residues in baby food were evaluated. A liquid chromatography–tandem mass spectrometry technique combined with electrospray ionization (ESI), (LC–MS/MS) and gas chromatography–mass spectrometry detection (GC–MSD) technique were applied in the detection of 50 pesticides in baby food. So-called QuEChERS (quick, easy, cheap, effective, rugged and safe) method was used as a sample preparation procedure. The recoveries were investigated at three levels (5, 10 and 50 μg/kg) and the results obtained showed compliance with the contemporary EU requirements with a few exceptions. LOQs for most of the tested pesticides were below the EU MRLs (10 μg/kg), except deltamethrin, cypermethrin, fenvalerate, phosalone and beta-cyfluthrin (LOQs were 10 μg/kg). Both techniques were applied in the analysis of 50 samples of baby food manufactured in Serbia.     

Finding of pesticides in fashionable fruit juices by LC–MS/MS and GC–MS/MS

Products labelled as containing extracts from two mushrooms (cordyceps plus reishi) and the juices from açaí, goji, mangosteen, noni, pomegranate, and sea buckthorn have been analysed for 174 different pesticides, using the validated QuEChERS method for sample preparation and electrospray LC–MS/MS in the positive ion mode for analysis. Pesticides were found in 10 of the 21 samples analysed. Most pesticides found were below the tolerance levels (1–6 μg/g, depending on the pesticide), but some were not. This included boscalid, dimethomorph, iprovalicarb, pyridaben, pyrimethanil, and imazalil, for which there is no tolerance reported or zero tolerance in any fruit. However, genuine açaí that was harvested in the state of Pará and lyophilised in Rio de Janeiro had no detectable pesticides, when analysed by both LC–MS/MS and GC–MS/MS, which can detect 213 more pesticides and industrial chemicals. Likewise no pesticides were found in one sample each of cordyceps plus reishi, sea buckthorn and noni.     

Determination of selected pesticides in fruit juices by matrix solid-phase dispersion and liquid chromatography–tandem mass spectrometry

A rapid and sensitive liquid chromatography–tandem mass spectrometry method has been developed for the analysis of acephate, monocrotophos, carbendazim, acetamiprid, dimethoate, simazine, carbofuran, atrazine, diuron, DNOC (4,6-dinitro-o-cresol), malathion and tebufenozide in fruit juices. Extracts were obtained by matrix solid-phase dispersion using diatomaceous earth as dispersant and dichloromethane as eluent. Significant matrix effects observed for most of the pesticides tested were eliminated using matrix-matched standards. The quantification of the analytes was carried out using the most sensitive transition. The confirmation of residues detected in real samples was performed by repeated injection and acquiring additional transitions to that used for quantification. Recoveries were in the range 71–118%. Repeatability of the method, expressed as the relative standard deviation, was in general between 5–15%. Low limits of detection (0.01–0.94 ng ml⁻¹) and quantification (0.03–3.12 ng ml⁻¹) were readily achieved with this method for all tested pesticides.     

Determination of phthalate esters in wine using solid-phase extraction and gas chromatography–mass spectrometry

A method for the determination of six phthalate esters in wine samples has been developed. The phthalates were extracted from wine samples with an optimised solid-phase extraction method on C18 column and quantification was achieved via gas chromatography coupled with a mass spectrometer. The method was linear between 0.015 and 5.000 μg mL⁻¹ for DMP, DEP and DEHP and between 0.018 and 5.000 μg mL⁻¹ for iBP, DBP and BBP. The LOQs of DMP, DEP and DEH were 0.024 μg mL⁻¹ while those of iBP, DBP and BBP were 0.029 μg mL⁻¹. The intra-day method repeatability was between 10% and 15% RSD, whereas the inter-day method repeatability was between 13% and 21% RSD. A survey was performed on white and red wines (n = 62) from the market, winemakers and an experimental pilot plant. All the analysed samples were phthalate contaminated. Commercial wine showed higher detection frequency and level of total phthalate, DBP and BBP than those produced in a pilot plant. iBP and DEHP concentrations were similar in all the groups of samples. iBP concentration was higher in red wines than in white ones.     

Characterization of nutritionally important phytoconstituents in minimally processed ready-to-eat baby-leaf vegetables using HPLC–DAD and GC–MS

Ready-to-eat baby-leaf vegetable market has been rapidly growing and offering to consumers convenient and appealing products, rich in health beneficial bioactive compounds. In the present study, the composition of carotenoids, tocopherols, and fatty acids were analyzed in seven baby-leaf vegetables using HPLC–DAD and GC–MS. Among the vegetables, the maximum amount (μg/g FW) of All-E-violaxanthin (42.77), 9′-Z-neoxanthin (22.13), All-E-lutein (69.67), All-E-β-carotene (60.18), total carotenoids (195.21), γ-tocopherol (19.68) and total tocopherol (47.68) were found in Batavian lettuce (Lactuca sativa L. var. Acephala). In all the studied baby-leaf vegetables, α-linolenic acid (ALA, C18:3) was found in highest quantity (44.73–54.39 %) followed by palmitic acid (C16:0) (13.02–19.49 %), and linoleic acid (C18:2) (8.25–21.54 %). Significantly high amount polyunsaturated fatty acids (PUFA) were recorded in Batavian lettuce (74.33 %) and red Romaine (72.72 %), compared to other studied vegetables. In view of health benefits, baby-leaf vegetables contain a low amount of saturated fatty acids and high-mono and PUFA, which can enhance the health benefits of these vegetables. Carotenoids in most of these studied baby-leaf vegetables can be classified as very high. Knowledge of carotenoid, tocopherols and fatty acids composition in different baby-leaf vegetables will be useful to nutritional experts for selection of nutrient-dense plants for food fortification and proper diet recommendation. To our knowledge, this is the first report on fatty acids composition from baby-leaf vegetables.     

Distribution and migration study of pesticides between peel and pulp in grape by online gel permeation chromatography–gas chromatography/mass spectrometry

A multi-residue method for the analysis of 175 pesticides was developed by online gel permeation chromatography–gas chromatography/mass spectrometry (GPC–GC/MS) to study pesticide distribution and migration between peel and pulp in grape. The separated peel and pulp samples were extracted by acetonitrile after fortified with chlorpyrifos-d₁₀ isotope internal standard. The extract was first purified by solid phase distribution sorbent of primary secondary amine (PSA) and then detected by online GPC–GC/MS. At the spiking levels of 10, 50 and 200 μg kg⁻¹, 73.7%, 94.3% and 98.9% of the pesticides, respectively, presented recoveries between 70% and 120%. The ratios were 91.4%, 94.9% and 92.0%, respectively, for the relative standard deviations (RSDs) bellow 15%. Limits of detection (LODs) for the pesticides in pulp were below 10 μg kg⁻¹. Pesticides were separated to four groups according to the distribution ratios (peel/whole grape) of 100%, 80–99.9%, 50–80% and 0–50% in peel. Relationship between the pesticide distribution and corresponding regulation of EU maximum residue level (MRL) was discussed. Six factors influencing the pesticides distribution and migration between peel and pulp were discussed. Weak linear correlation between the pesticide solubility in water (20 °C) and the distribution ratios (lowest and average) in peel was found for most of the detected pesticides with solubility less than 200 mg L⁻¹.     

Optimization of gas chromatography–single quadrupole mass spectrometry conditions for multiresidue analysis of pesticides in grapes in compliance to EU-MRLs

A single quadrupole GC–MS method was optimized for multiresidue determination of 47 pesticides in grapes with limit of quantifications of each compound in compliance with the EU-MRL requirements. Sample preparation involved extraction of 10 g sample with 10 ml ethyl acetate (+10 g sodium sulphate) by homogenization at 15,000 rpm followed by centrifugation at 3000 rpm. The supernatant was cleaned by dispersive solid phase extraction with primary secondary amine and acidified with 0.1% formic acid. Residues were estimated in selected ion monitoring mode with programmable temperature vaporizer-large volume injection (8 μl). All the GC and MS parameters were thoroughly optimized to achieve satisfactory linearity (R² > 0.99) within 0.01–0.25 mg kg⁻¹ with minimum matrix interferences. Recoveries at 0.01 and 0.02 mg kg⁻¹ were within 67–120% with associated precision RSD below 19%. The method was successfully applied for analysis of the real world samples for incurred residues.     

Application of dispersive liquid–liquid microextraction for the determination of selected organochlorine pesticides in honey by gas chromatography–mass spectrometry

Dispersive liquid–liquid microextraction (DLLME) is a rapid and easy technique that consumes minute amounts of organic solvents. In this work, we present chemometric study on optimization of DLLME parameters for the extraction of aldrin, endrin, lindane, α-endosulfan, 4,4′-DDT and its metabolites from honey matrix. Method quantification limits (MQLs) vary between 0.3 ng/g for 2,4′-DDE and 4,4′-DDE to 13.2 ng/g for α-endosulfan and enable determination at levels below EU-established Maximum Residue Limits. The developed method is linear (R ² > 0.994) in the investigated range (MQL—100 ng/g), with preconcentration factors of 13.2–30.5 and good repeatability (CV ≤ 17%). A comparison with other available methods reported in the last decade is provided. The method has been applied to 19 real samples from Poland, and the results show that organochlorine pesticides (OCPs) are present in analysed honeys at levels not posing threat to human health (below 14 ng/g for sum of 4,4′-DDT and metabolites and below 5 ng/g for aldrin, endrin and lindane). To the best of our knowledge, this is the first reported application of DLLME for the determination of OCPs in honey.     

Quantification of main phenolic compounds in sweet and bitter orange peel using CE–MS/MS

The food and agricultural products processing industries generate substantial quantities of phenolics-rich subproducts, which could be valuable natural sources of polyphenols. In oranges, the peel represents roughly 30% of the fruit mass and the highest concentrations of flavonoids in citrus fruit occur in peel. In this work we have carried out the characterisation and quantification of citrus flavonoids in methanolic extracts of bitter and sweet orange peels using CE–ESI–IT–MS. Naringin (m/z 579.2) and neohesperidin (m/z 609.2) are the major polyphenols in bitter orange peels and narirutin (m/z 579.2) and hesperidin (m/z 609.2) in sweet orange peels. The proposed method allowed the unmistakable identification, using MS/MS experiments, and also the quantification of naringin (5.1 ± 0.4 mg/g), neohesperidin (7.9 ± 0.8 mg/g), narirutin (26.9 ± 2.1 mg/g) and hesperidin (35.2 ± 3.6 mg/g) in bitter and sweet orange peels. CE coupled to MS detection can provides structure-selective information about the analytes. In this work we have developed a CE–ESI–IT–MS method for the analysis and quantification of main phenolic compounds in orange peels.     

Determination of methylmercury in marine and freshwater fish in Ghana using a combined technique of dithizone extraction and gas–liquid chromatography with electron capture detection

Concentrations of methylmercury (MeHg) residues were determined in different marine and freshwater fishes from Ghana. Samples were treated with ethanolic potassium hydroxide in water bath at 100 °C for 1 h. After neutralising with HCl and washing with hexane, MeHg was extracted with dithizone in toluene, cleaned up and determined by gas chromatography with electron capture detection (GC–ECD). The method was sensitive with good precision, detection limit of 0.0005 μg g⁻¹ (0.5 μg kg⁻¹) and provided good separation for organomercury compounds. The validity of the method was established using dogfish muscle certified reference material, DORM-2. The method was applied to different fish species. Concentration of MeHg in the edible muscle tissue of the tested fish ranged from 0.009 to 0.107 μg g⁻¹ wet weight. The concentrations of MeHg in the fish samples obtained do not however, constitute any significant mercury exposure to the general population through consumption of the tested fish species.     

Improved incorporation and stabilisation of β-carotene in hydrocolloids using glycerol

In this paper, a novel method for the incorporation of the antioxidant β-carotene in hydrocolloid matrices is presented, which consists on the use of glycerol as the vehicle for incorporation. This alcohol has been observed to greatly photostabilise the carotenoid molecule within the hydrocolloid matrices without greatly affecting the mechanical properties of the materials. The UV stability of β-carotene in the different hydrocolloid films developed (including starch, soy protein, whey protein concentrate, gelatin and zein) has been studied using UV/visible spectrophotometry, colorimetry and Raman spectroscopy. Raman images of the materials were also generated in order to ascertain the dispersion of the antioxidant within the hydrocolloid materials and it was observed that β-carotene was partially agglomerated in certain areas of the film, fact that could also contribute to enhance the stability of the bioactive molecule.     

Rapid screening and identification of antioxidants in aqueous extracts of Houttuynia cordata using LC–ESI–MS coupled with DPPH assay

Houttuynia cordata Thunb. has been used traditionally as immune stimulant and anticancer agent. An aqueous extract of H. cordata tea showed high radical scavenging activity determined by off-line DPPH assays. Then, it was screened for its antioxidant components via an on-line DPPH radical scavenging technique coupled with a liquid chromatography–electrospray ionization mass spectrometer (LC–ESI–MS). Based on their mass spectra and fragmentation patterns; the antioxidant compounds were identified as quinic acid derivative, caffeic acid derivatives, procyanidin B, neo-chlorogenic acid, catechin, chlorogenic acid, crypto-chlorogenic acid and quercetin hexoside. LC–MS/MS in multiple reactions monitoring (MRM) mode was used to quantify these antioxidant compounds. Chlorogenic acid was found to be a major component in H. cordata tea.     

Some pesticides occurrence in air and precipitation in Québec, Canada

Air and precipitation samples were collected in three stations located in Quebec between January 1993 and March 1996 to determine spatial and seasonal variations of several organochlorine pesticides and metabolites (alpha-HCH, gamma-HCH, HCB, gamma-chlordane, DDT, DDE, Mirex). alpha-HCH, gamma-HCH, and HCB were more or less measured in large amounts at all sites, whereas gamma-chlordane, DDT, and DDE concentrations were lower and Mirex was undetectable. Higher concentrations levels were observed in air during hot spring/summer periods except for HCB, indicating a probable temperature dependence. Ln concentrations vs reciprocal temperature plots and Henry's law determinations helped to highlight the contribution of soil and/or water volatilization of those compounds. Itwas observed that alpha-HCH came mainly from Atlantic Ocean volatilization at Mingan, whereas sources of gamma-chlordane and DDE were mostly due to volatilization from soils in southern Quebec. DDT may be present in the atmosphere by the way of transport from remote regions. Lindane sources were multiple: it may be found in the atmosphere bythe processes of transport and volatilization coming from soil or water. Finally, a negative correlation between HCB and air temperature implies that processes other than volatilization are involved in transport of this compound.     

Determination of danofloxacin in milk combining second-order calibration and standard addition method using excitation–emission fluorescence data

For this paper we propound a new procedure for fast detection and determination of danofloxacin (DANO) in commercial bovine milks. For this aim, a spectrofluorimetric method coupled with chemometric (PARAFAC) tools has been optimized. This method provides valuable information about the total amount of DANO in the selected sample in a short analysis time. After a cleanup step, consisting in protein precipitation in acidic medium, excitation–emission fluorimetric scans (EMMs) were recorded and a standard addition calibration method, using second order multivariate procedures, was applied. The analytical method has been validated according to the European Community directive related to the decision limit (CCα) and detection capability (CCβ). The obtained values, 7.3 and 12 ng mL⁻¹, respectively calculated are well below the MRL for DANO in milk (30 ng mL⁻¹). This procedure has been applied to different commercial milks in order to accomplish the strength of this methodology by PARAFAC standard addition. Recoveries around 100% were observed for all the samples. The high sensitivity of the fluorimetric technique and the fast cleanup step make this method an easy and fast way for quality and antibiotic residues surveys in commercial milks.     

Measurement of malonaldehyde in apple juice using GC–MS and a comparison to the thiobarbituric acid assay

Malonaldehyde (MA) in gamma-irradiated apple juice was measured using a GC–MS method and in comparison to the thiobarbituric acid (TBA) assay. The profiles of MA content as a function of radiation dose were similar using both methods, however, MA content was higher when measured with the TBA assay compared to the GC–MS method. The overestimation of MA using the TBA assay increased as the amount of MA decreased. Use of the GC–MS method demonstrated MA content in irradiated juice declined rapidly during storage at 5 °C. MA content appeared to decrease much less when the TBA assay was used. The GC–MS method also allowed measurement of formaldehyde and acetaldehyde in addition to MA.     

Inactivation of Salmonella Typhimurium in fresh cherry tomatoes using combined treatment of UV–TiO2 photocatalysis and high hydrostatic pressure

Food Science and Biotechnology - The antibacterial efficacy of UV–TiO2 photocatalysis pre-washing in a water-assisted system (UVT, 4.5 mW/cm2, 5–15 min) and high...     

Improved synthesis of isomaltooligosaccharides using immobilized α-glucosidase in organic–aqueous media

Food Science and Biotechnology - α-Glucosidase was immobilized onto an epoxy-activated resin (Eupergit C) to catalyze maltose into isomaltooligosaccharides (IMO), and then the effects of...