A critical comparison between an ultra-high-performance liquid chromatography triple quadrupole mass spectrometry (UHPLC-QqQ-MS) method and an enzyme assay for anti-cholinesterase pesticide residue detection in cereal matrices.

Analytical method development for the control of pesticide residues occurring in significant dietary foodstuffs is of utmost importance considering their potential impact on consumer health and food market sustainability. Depending on the purpose, either instrumental analysis, mainly chromatographic methods, or screening assays, mostly using biorecognition affinity, are commonly used, featuring different advantages and drawbacks. To practically compare these two different types of analytical strategies, we applied them for the detection of (i) 97 organophosphate (OP) and carbamate (CM) pesticide residues in wheat flour and (ii) carbofuran (a carbamate insecticide) in wheat, rye and maize flour samples. Regarding high-end analysis, an ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC-QqQ-MS) method was developed and validated achieving low limits of quantification (LOQs, from 0.002 to 0.040 mg kg-1) and a short chromatographic run (12 min). In terms of bioanalytical methods, a fast (17 min) and cost-efficient (∼0.01€ per sample) acetylcholinesterase (AChE) microplate assay for carbofuran screening was utilized. Importantly, carbofuran was the strongest of the 11 OP and CM tested pesticides achieving a half maximal inhibitory concentration (IC50) of 0.021 µM whilst the assay detectability was at the parts per billion level in all three cereal matrices. Based on the attained results, a critical discussion is presented providing the analytical merits and bottlenecks for each case and a wider outlook related to the application of analytical methods in the food safety control analytical scheme.

A microfluidic paper-based analytical device (µPAD) with smartphone readout for chlorpyrifos-oxon screening in human serum.

Acute intoxication incidents due to neurotoxic organophosphate (OP) insecticides are occasionally reported, related either to suicidal attempts or occupational exposure due to the misuse of protective equipment. Among them, chlorpyrifos is a compound related to great controversy, which is still authorized and easily accessible in many countries around the world. However, to screen for its exposure markers, instrumental methods are commonly applied, which cannot enable rapid monitoring at an early stage of an intoxication. Therefore, in this study, a microfluidic paper-based analytical device (µPAD) able to rapidly screen for chlorpyrifos-oxon, the toxic chlorpyrifos metabolite, in human serum was developed and fully validated. The µPAD combines wax-printed butyrylcholinesterase (BChE) paper sensors, a lab-on-a-chip (LOC) prototype injector and a smartphone as the analytical detector. In principle, the wax-printed strips with adsorbed BChE are embedded into LOC injectors able to deliver samples and reagents on-demand. A smartphone reader was used to monitor the color development on the strips providing binary qualitative results. µPAD method performance characteristics were thoroughly evaluated in terms of specificity, detection capability (CCß) and ruggedness. The developed analytical platform is rapid (results within 10 min), cost-efficient (0.70 €), potentially applicable at the point-of-need and attained a low CCß (10 µg L-1 in human serum). Finally, µPAD characteristics were critically compared to well-established methods, namely an in-house BChE microplate assay and liquid chromatography tandem mass spectrometry.

Lorazepam photofate under photolysis and TiO2-assisted photocatalysis: identification and evolution profiles of by-products formed during phototreatment of a WWTP effluent.

This manuscript reports on the study of Lorazepam (LZP) phototransformation pathways under artificial UV and natural solar irradiation, through photolytic and TiO2-assisted photocatalytic processes. Three experimental set-ups were employed: two lab-scale photoreactors, each provided with an UV lamp (one medium pressure mercury lamp and one blacklight blue lamp), and a pilot-scale Solar Plant with Compound Parabolic Collectors (CPCs). Samples collected along the different phototreatment experiments were analyzed by ultra-high performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry (UHPLC/QqToF-MS). The key assumption of the analytical approach was that related compounds (LZP and its by-products (LBPs)) provide identical "diagnostic fragment ions". Identification was also based on the chlorine atoms specific isotopic pattern, as well as accurate masses. Six major LBPs were identified and elucidated, with nominal [M + H](+) masses of 337, 303, 319, 275, 291 and 293 Da. The proposed LZP photodegradation mechanism included the initial opening of the diazepinone seven-membered ring, followed by a rearrangement into a highly stabilized six-membered aromatic ring and subsequent cleavage and/or hydroxylation reactions. The evolution profiles of LBPs were described for each of the three experimental prototypes and the CPCs Solar Pilot Plant proved to be the most efficient one. Finally, LZP photocatalytic degradation was further assessed on a municipal effluent, where the photoproducts generated showed to be more persistent than LZP itself.

A fast and simple procedure for determination of perfluoroalkyl substances in food and feed: a method verification by an interlaboratory study.

In this study, a simple, fast, and cheap sample preparation procedure for the analysis of three well-known representatives of perfluoroalkyl substances (perfluorooctane sulfonate, perfluorooctanoic acid, and perfluorooctane sulfonamide) was validated in accordance with Commission Decision 2002/657/EC. The method was based on extraction with methanol followed by a dispersive solid phase extraction cleanup step by addition of activated charcoal for fish tissue, fish feed, and milk samples. The novel analytical approach combined with liquid chromatography-tandem mass spectrometry makes it possible to achieve limits of quantification below 1 µg/kg (defined by Commission Recommendation 2010/161/EU). This method provides a high laboratory sample throughput: ten samples in 60 min. The validated procedure was successfully verified in an interlaboratory study.

Occurrence of brominated flame retardants in household and car dust from the Czech Republic.

The levels and profiles of 16 polybrominated diphenyl ethers congeners (PBDEs), three isomers of hexabromocyclododecane (HBCD) and other six "alternative" brominated flame retardants (BFRs) in dust collected in 25 Czech households and 27 car interiors were investigated. The Σ16 PBDEs contents varied widely with maximum concentrations reaching up to 5896 and 33728 µg/kg in house and car dust, respectively. The highest concentrations of PBDEs were observed for BDE 209, which was found almost in all samples and exceeded concentrations of other PBDEs even by one order of magnitude. The profile and levels of Penta-, Octa-, and DecaBDE obtained within this study were comparable to those presented in other studies worldwide and confirmed lower contamination of dust from Europe compared to North America. From the group of "alternative" BFRs, suitable for commercial applications as an alternative to banned PBDEs, mainly decabromodiphenyl ethane (DBDPE) and HBCD were detected in the concentration ranges <20-3567 and <0.3-950 µg/kg, respectively. γ-HBCD was dominating, forming up to 70% of ΣHBCD. Using the measured concentrations and estimates of dust ingestion rates it was estimated that toddlers had a higher exposure than adults for all compounds investigated.

Polybrominated diphenyl ethers (PBDEs) contents in house and car dust of Portugal by pressurized liquid extraction (PLE) and gas chromatography-mass spectrometry (GC-MS).

Dust is the repository of various compounds including flame retardants. In this study an analytical method based on PLE extraction and gas chromatography-mass spectrometry was selected for the analysis of 16 PBDEs congeners in house and car dust samples collected in Portugal. The analytical performance of the method was validated using standard reference material (SRM); values from 90% to 109% and from 2% to 11% were obtained for recovery and precision, respectively. The PBDE congeners distribution in whole and sieved fractions of the dust samples, as well as influence of the source on the levels of these contaminants, were obtained. The wide range of PBDEs contents found in the dust samples indicates heterogeneous levels of contamination in these matrices. The clearest feature of the results obtained was that Deca-BDE was the main PBDE in both house and car dust samples. The total PBDEs measured in house dust (ranging from 34 to 1928 ng g(-1)) was lower than those found in car dust (ranging from 193 to 22955 ng g(-1)). However, house dust provides a major contribution to human exposure due to the time spent there, much higher than in cars.

Effects of pollution on chub in the River Elbe, Czech Republic.

The Elbe River is one of the most polluted aquatic ecosystems in the Czech Republic. The effect of three major chemical plants located on the Elbe River (at Pardubice, Neratovice, and Usti nad Labem) on fish was studied in 2004. Health status, chemical concentrations (Hg, PCB, DDT, HCH, HCB, OCS, 4-tert-nonylphenols, 4-tert-octylphenol) in muscle, and biomarkers (hepatic ethoxyresorufin-O-deethylase (EROD), plasma vitellogenin, and plasma 11-ketotestosterone) were assessed in male chub (Leuciscus cephalus L.). Differences between localities upstream (US) and downstream (DS) from the monitored source of pollution were identified. Fish from DS sampling sites showed significantly higher levels of contaminants than fish from US sampling sites. Generally, the concentrations of pollutants in fish from the Elbe sites were significantly higher compared to the reference site. Reduced gonad size, decreased plasma levels of 11-ketotestosterone, EROD and vitellogenin induction, and histopathologies of male gonads indicated harmful effects of aquatic pollution in fish from the Czech portion of the Elbe River.

Organic pollutants in areas impacted by flooding in 2002: a 4-year survey.

This paper summarizes a 4-year survey focused on polycyclic aromatic hydrocarbons (PAHs) and halogenated persistent organic pollutants (POPs) in river sediments, soil and crops collected in the locality impacted by catastrophic floods that occurred in the western part of Bohemia in August 2002. In spite of relatively high levels of polychlorinated biphenyls (PCBs) in river sediments, the increase of these POPs in flooded arable soil was not significant. On the other hand, remarkably higher levels of PAHs and dichlorodiphenyl trichloroethane (DDTs) were found as compared to those in reference soil samples. Regardless of this increased soil pollution, no measurable elevated concentrations of POPs occurred in the wheat grown in this area.

Chub (Leuciscus cephalus) as a bioindicator of contamination of the Vltava River by synthetic musk fragrances.

Synthetic musk fragrances, which are contained in almost all scented consumer products, enter aquatic environment mainly by way of wastewater paths. To monitor contamination of the Vltava River by these relatively persistent chemicals in the surroundings of Prague industrialized agglomeration, chub (Leuciscus cephalus) was employed as a bioindicator. Validated gas chromatography-mass spectrometry method was used for fish sample examination. Polycyclic musks, represented by 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta-(gamma)-2-benzopyran (galaxolide) and 1-(5,6,7,8-tetrahydro-3,5,5,6,8,8-hexamethyl-2-naphthalenyl)-ethanone (tonalide) were the most abundant representatives of this group; their levels in fillets were in the range of 1.7 to 105.9 microg/kg and 0.9 to 19.3 microg/kg wet weight, respectively. Nitro-musks, musk ketone, and musk xylene were also detected in most samples; nevertheless, their levels were lower,