Sorption and mobility assessment of tembotrione in soils of upper, trans and middle Gangetic plain zones of India.

The presence of undesired agrochemicals residues in soil and water poses risks to both human health and the environment. The behavior of pesticides in soil depends both on the physico-chemical properties of pesticides and soil type. This study examined the adsorption-desorption and leaching behavior of the maize herbicide tembotrione in soils of the upper (UGPZ), trans (TGPZ) and middle Gangetic plain zones of India. Soil samples were extracted using acetone followed by partitioning with dichloromethane, whereas liquid-liquid extraction using dichloromethane was used for aqueous samples. Residues of tembotrione and its metabolite TCMBA, {2-chloro-4-(methylsulfonyl)-3-[(2,2,2-trifluoroethoxy) methyl] benzoic acid}, were quantified using liquid chromatography-tandem mass spectrometry. The data revealed that tembotrione adsorption decreased with increasing pH and dissolved organic matter but increased with salinity. The maximum adsorption occurred at pH 4, 0.01 m sodium citrate and 4 g/L NaCl, with corresponding Freundlich constants of 1.83, 2.28 and 3.32, respectively. The hysteresis index <1 indicated faster adsorption than desorption. Leaching studies under different flow conditions revealed least mobility in UGPZ soil and high mobility in TGPZ soil, consistent with groundwater ubiquity scores of 4.27 and 4.81, respectively. Soil amendments decreased tembotrione mobility in the order: unamended > wheat straw ash > wheat straw > farm yard manure > compost. The transformation of tembotrione to TCMBA and its mobility in soil columns were also assessed.

Methoxetamine and its metabolites: Postmortem determination in body fluids of human cadaver.

We report the forensic case of a 42-year-old man, a known drug user, who died at home and whose body was only discovered 2 months later. Autopsy was performed on a corpse in the late postmortem stage where no apparent cause of death was found. A toxicological screening of biological materials (blood, urine and gastric content) using liquid chromatography with different types of mass detection (ion trap and high-resolution) revealed the presence of methoxetamine (MXE), a ketamine analog, and its metabolites. MXE and a number of its metabolites (e.g., O-desmethyl, N-desethyl, hydroxy, glucuronides and sulfates) were identified in urine. Based on the results, a method using liquid chromatography with tandem mass spectrometry was developed and validated for the determination of MXE concentration in biological materials. The following values of MXE concentration were found: blood-3.6 ng/mL, urine-70.5 ng/mL and gastric content-18.0 ng/mL. Given the absence of other drugs, medications and poisons, it can be inferred that despite relatively low blood concentrations, MXE contributed to the victim's death. The present case demonstrates that even after 2 months, MXE and its several metabolites can be detected and determined in the human cadaver at a relatively advanced stage of decomposition.

Non-targeted analysis of co-formulants in antifungal pesticide formulations by gas chromatography-tandem high resolution mass spectrometry.

In the present study, six commercial pesticide formulations with antifungal activity were characterized. Thus, two complementary injection methods based on gas chromatography were employed: direct injection (DI) and headspace (HS), both coupled to high resolution mass spectrometry (GC-Q-Orbitrap-MS). The combination of both injection modes allowed the tentatively identification of potential co-formulants. Available analytical standards were acquired for their confirmation, and 21 compounds were successfully confirmed. Finally, the concentration of these co-formulants was calculated, finding the highest value in one of the pesticide formulation, at 218.22 g L-1 for cyclohexanone. Results clearly show that this methodology is suitable for the reliable identification of co-formulants in pesticide formulations, offering high sensitivity, and highlighting that five co-formulants were detected by both injection techniques (DI and HS). Moreover, one of the main advantages of the proposed methods was the great capacity for the elucidation of compounds with similar molecular formula, bearing in mind that up to 8 co-formulants with the same molecular formula C10H14, were well differentiated by retention times between 8.46 (1-methyl-3-propylbenzene) and 10.98 min (1,2,3,4- tetramethylbenzene) in one of the pesticide formulation. Toxicity to human health and the environment has been evidenced for the co-formulants detected, finding compounds with relatively high toxicity, as naphthalene and cyclohexanone.

Occurrence of 2- and 3-monochloropropanediol esters (MCPDE) in infant formula products on the Canadian market between 2015 and 2019.

2- and 3-monochloropropanediol esters (MCPDEs) are most commonly formed as process-induced contaminants during the refinement of vegetable oils used for food production. 'In vivo' hydrolysis of 3-MCPDEs releases the potential carcinogen 3-monochloropropanediol (3-MCPD). Levels of MCPDEs in infant formula are of particular concern, as refined oils are commonly used as main fat ingredients. For this study, infant formula samples (powders, liquid concentrates and ready-to-feed infant formula samples) from the Canadian market were purchased and analysed in 2015 (35 samples) and 2019 (33 samples). MCPDE concentrations (expressed as free MCPD equivalents) were examined through an indirect analytical approach, applying acid-catalysed ester cleavage and using cyclohexanone as derivatising agent. Labelled diesters were used as internal standards. 2015 Survey data were analysed by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode (SIM). 2019 Survey data were analysed with an updated method using GC-MS/MS in multiple reaction monitoring modes (MRM). In 2015, levels in reconstituted formula ranging from 3.7 ng/g to 111 ng/g for 3-MCPD and 2.2 ng/g to 56.2 ng/g for 2-MCPD were found. In 2019, levels ranging from 3.9 ng/g to 74.8 ng/g for 3-MCPD and 1.0 ng/g to 33.9 ng/g for 2-MCPD were found. A significantly reduced mean of combined MCPDEs was observed between 2015 and 2019 data (64.5 ng/g, standard deviation (SD) 8.6 ng/g in 2015 to 31.8 ng/g, SD 5.6 ng/g in 2019, p-value = 0.024). For the majority of manufacturers, the data comparison among brand products over time shows decreased levels of MCPDEs. Occurrence data of MCPDEs, including data from previously published surveys (2012/2013), were also compared and a temporal trend was established.

Design and Fabrication of Yttrium Ferrite Garnet-Embedded Graphitic Carbon Nitride: A Sensitive Electrocatalyst for Smartphone-Enabled Point-of-Care Pesticide (Mesotrione) Analysis in Food Samples.

As the use of pesticides in agriculture is increasing at an alarming rate, food contamination by pesticide residues is becoming a huge global problem. It is essential to develop a sensitive and user-friendly sensor device to quantify trace levels of pesticide and herbicide residues in food samples. Herein, we report an electrocatalyst made up of yttrium iron garnet (Y3Fe5O12; YIG) and graphitic carbon nitride (GCN) to attain picomolar-level detection sensitivity for mesotrione (MTO), which is a widely used herbicide in agriculture. First, YIG was prepared by a hydrothermal route; then, it was loaded on GCN sheets via a calcination method. The surface structures, composition, crystallinity, and interfacial and electrocatalytic properties of the YIG and YIG/GCN were analyzed. As the YIG/GCN displayed better surface and catalytic properties than YIG, YIG/GCN was modified on a screen-printed carbon electrode to fabricate a sensor for MTO. The YIG/GCN-modified electrode displayed a detection limit of 950 pM for MTO. The method was demonstrated in (spiked) fruits and vegetables. Then, the modified electrode was integrated with a miniaturized potentiostat called KAUSTat, which can be operated wirelessly by a smartphone. A first smartphone-based portable sensor was demonstrated for MTO that is suitable for use in nonlaboratory settings.

Simultaneous determination and dietary risk assessment of clethodim and its metabolites in different fruits and vegetables.

Clethodim is one of the most widely used herbicides in agriculture and, after field application, is metabolised to several metabolites. The potential toxicological negative effects of these compounds are poorly understood. Thus, recently, within the risk assessment framework, the European Food Safety Authority (EFSA) proposed to include the minor metabolites in the definition of clethodim residue. In this work, an easy to use and reliable UHPLC method coupled with a triple quadrupole MS/MS was developed and validated for the detection and quantification of the herbicide clethodim and related metabolites clethodim sulphone, clethodim sulphoxide, metabolites M17R and M18R in apple, grape, olive and rice. The five analytes were extracted by using a modified QuEChERS procedure, while the active ingredients were determined in multiple reaction monitoring (MRM) ion-switching mode. The proposed method showed calibration curve linearity with r2 ≥ 0.990 for all active ingredients (a.is.) both in solvent and matrix extracts. Limits of quantitation (LOQ) of the five compounds ranged from 9.44 µg/kg for M17R in olive extract to 11.01 µg/kg for clethodim in apple extract. Recoveries values ranged from 86% to 119% at two concentration levels (LOQ and 10xLOQ), while the intraday and interday precisions of the method were both below 10% in all cases. The method was successfully used for the quantification of the five a.is. in different food matrices. Furthermore, chronic dietary risk was investigated using a hazard quotients (HQ) method based on European dietary habits. The chronic dietary exposure risk quotients ranged from 1.0 × 10-5 (lower bound scenario) to 2.7 × 10-4 (upper bound scenario) which were significantly lower than 1. Data obtained indicate that the dietary exposure risks were acceptable for clethodim and its major and minor metabolites applied in apple, table grape, rice and table olive.

Ultimate fate of herbicide tembotrione and its metabolite TCMBA in soil.

Tembotrione is a triketone group herbicide having worldwide applications for weed management in maize. It is considered to be less stable in the environment and its degradation products may have toxicological consequences due to longer persistence and off-site movements. We studied the persistence behavior and leaching potential of tembotrione and its major metabolite TCMBA in clay loam and sandy loam soils having different physico-chemical properties. The rapid transformation of parent tembotrione to degradation products and their high interactions with soil provided challenging task of residues separation from complex soil matrix. Therefore, a novel sample preparation method (modified QuEChERS) was optimized for trace estimation of tembotrione and TCMBA which offered 86.6-95.6% recoveries with limit of detection (LOD) and quantification (LOQ) as 0.001 and 0.003 µg/g, respectively in both soils without any matrix interference. A first order dissipation kinetics was followed by tembotrione and TCMBA residues with half-life ranged from 7.2 to 13.4 days in both soils. Residues reached below detectable limit on 45-60 days after treatments in two application doses. Leaching experiment revealed maximum retention of tembotrione residues from 15 to 25 cm depth in both soils whereas TCMBA show appreciable leaching potential. It was concluded that tembotrione can be phytotoxic to the succeeding crops if applied at late post-emergence stage. TCMBA can contaminate surface and ground water due to continuous and prolonged use of tembotrione particularly in light textured soils.

Development and establishment of a QuEChERS-based extraction method for determining tembotrione and its metabolite AE 1417268 in corn, corn oil and certain animal-origin foods by HPLC-MS/MS.

In this study, we established a rapid and sensitive HPLC-MS/MS method for quantitative determination of tembotrione and its metabolite AE 1417268 (M5) in corn, corn oil, beef, pork, chicken, and eggs. Both analytes eluted from a C18 column within 6 min. The electrospray ionisation-positive mode was used for tembotrione, whereas the negative mode was used for M5. Acetonitrile was the extractant for all samples, and the addition of 2 g NaCl to each homogenised sample facilitated the extraction of the analytes into acetonitrile. The extracted analytes were further purified by the addition of 50 mg of C18 sorbent (25 mg GCB was also added to corn samples) for subsequent HPLC-MS/MS analysis. Satisfactory calibration-curve linearities (R2 ≥ 0.997) were obtained for the two analytes at concentrations of 1-500 µg/L. Mean recoveries in different matrices ranged from 73.7% to 110.4%, whereas intra-day and inter-day relative standard deviations were <15% for all concentrations of spiked analytes. The limit of quantification was 2 µg/kg for each analyte in all matrices. In food samples obtained from markets, residual tembotrione and M5 were all below the limits of quantification. These results confirm that the method is suitable for the routine monitoring of residual tembotrione and M5 in a variety of food matrices.

Chemometrics based GC-MS aroma profiling for revealing freshness, origin and roasting indices in saffron spice and its adulteration.

Saffron, stigmas of Crocus sativus, is one of the most precious spices used as food colorant and flavoring agent. Due to its scarce source and high cost, it is liable to fraudulent admixture with allied plants "safflower and calendula". In this study, gas chromatography-mass spectrometry (GC-MS) was employed to determine authenticity, adulterants detection, and to assess the roasting impact on its aroma. A total of 93 volatiles were identified belonging to different classes viz. aldehydes, alcohols, ketones, aliphatic hydrocarbons, aromatics, mono-and sesquiterpenes, oxides/ethers and pyrans/furans. Principle component analysis (PCA) identified safranal and 2-caren-10-al as discriminatory volatile markers of saffron from its allied flowers, later found enriched in estragole, ß-caryophyllene and eugenol. PCA model also revealed markers for freshly dried versus long-stored saffron, with ketoisophorone as freshness marker versus safranal as an ageing indicator. Safranal was further identified as a marker to distinguish saffron from safflower, whereas calendula aroma was predominated by monoterpene hydrocarbons.

Dissipation behavior, residues distribution and dietary risk assessment of tembotrione and its metabolite in maize via QuEChERS using HPLC-MS/MS technique.

The dissipation and residues of tembotrione in corn field application were investigated using liquid chromatography tandem mass spectrometry (LC-MS/MS) method. The average recoveries of tembotrione in maize, corncob, and straw were in the ranges of 98-107% with relative standard deviations (RSDs ≤9.3%), respectively. The recoveries of M5 was in the ranges of 90-108% in all three matrices of maize, with RSDs were 3.3-12.8%. The LODs for tembotrione and M5 in maize were 0.85 µg/L and 1.0 µg/L, 0.84 µg/L and 0.43 µg/L in corncob, 0.94 µg/L and 1.5 µg/L in straw, respectively. The LOQs of the method in maize grain, corncob and straw were 0.01, 0.01 and 0.05 mg/kg for both analytes, respectively. The dissipation of tembotrione in straw was in compliance with the first-order dynamic equation, with half-lives of 1.18-1.23 days at Beijing and Heilongjiang. Total residue of tembotrione in maize grain and corncob matrix were both below 0.02 mg/kg, lower than the max residue limit (MRL) recommended by european food safety authority (EFSA). Risk quotients (RQs) of this pesticide was assessed via comparing national estimated daily intake with acceptable daily intake. The dietary intake risk of tembotrione residue in maize was very low for all groups of Chinese residents. These data could provide scientific data and strategies and facilitate Chinese government to establish the MRLs of tembotrione.

Comparison of three collection methods for the sodium rhodizonate detection of gunshot residues on hands.

The aim of this study was to compare three gunshot residue (GSR) collection methods used in conjunction with chemographic detection applied by different regional Swiss police services. The specimens were collected from the hands of a shooter with either filter paper (Filter method) or adhesive foil. The adhesive foil was then either applied against photographic paper during visualisation (AF Photo method) or coated with a layer of polyvinyl alcohol (AF PVAL method). The experiments involved two conditions of the examined hands, i.e. dry and humidified. The residues were revealed using the sodium rhodizonate test (SRT). Preliminary tests assessing the possibility of conducting a confirmatory Scanning Electron Microscopy coupled to Energy Dispersive X-ray spectroscopy (SEM/EDX) analysis after the chemographic test were performed on a number of specimens by cutting positive spots and mounting them on stubs. Obtained results were compared in terms of effectiveness - number of positive spots, time requirements, quality of subsequent SEM-EDX analysis, ease of use and cost. The Filter method generally yielded a high-quality detection with both dry and humidified hands, as well as a simple, quick and efficient confirmation by SEM/EDX. The AF Photo performed well on dry hands, but not on humidified hands. The AF PVAL method performance was lower compared to the other methods in both examined conditions of the hands. The SEM/EDX analysis showed that the Filter and AF PVAL method provided satisfactory results when a sufficient carbon coating thickness was applied to the cuttings. It was also observed that the thinner the PVAL layer, the better the quality of the spectra and obtained images in SEM/EDX. Furthermore, the surface of the photographic paper did not seem to be conductive, even after the application of a thick layer of carbon. In conclusion, the Filter method gave the best overall results, but its application required slightly more time and expertise than the two other methods.

Metabolic profiles in the course of the shikimic acid pathway of Raphanus sativus var. longipinnatus exposed to mesotrione and its degradation products.

The influence of pesticides on the metabolism of edible plants has not been fully investigated. Moreover, once introduced into the environment, pesticides are degraded to many compounds with undefined bioactivity. In presented work, under experimental conditions, model edible plant (Raphanus sativus var. longipinnatus) was exposed to herbicide stress by application of a herbicide (mesotrione, 2-(4-methanesulfonyl-2-nitrobenzoyl)cyclohexane-1,3-dione, MES) or its degradation products (amino-4-(methylsulfonyl)benzoic acid, AMBA; 4-(methylsulfonyl)-2-nitrobenzoic acid MNBA; cyclohexane-1,3-dione, CHD). Metabolic profiles of plants were employed to estimate the plant's defence response to MES and its metabolites. The intensity of herbicide stress was determined by measuring the changes in chlorophyll and catecholamines concentration formed in the shikimic acid pathway. Non-target analysis was conducted by LC-MS/MS, determination of catecholamines by LC-FL, chlorophyll by spectrophotometry. The highest phytotoxicity is characterized by MES (2000%-fold increase in the content of herbicide stress marker (normetanephrine) compared to a blank), followed by CHD (500%) combined with 15% increase in chlorophyll concentration. AMBA and MNBA as stress factors caused the increase in the content of catecholamines in the plant (86-160%). Simultaneously, an increase in chlorophyll content was observed (26-50%). Such diversity of the organism's defence response, also visible on metabolic profiles, can be associated with the chemical structure of compounds that are stress factors. MES and CHD, in contrast to AMBA and MNBA, have cyclohexano-1,3-moiety in their structure, which seems to be responsible for herbicidal properties.

Identification and distribution of mycosporine-like amino acids in Brazilian cyanobacteria using ultrahigh-performance liquid chromatography with diode array detection coupled to quadrupole time-of-flight mass spectrometry.

RATIONALE: Mycosporine-like amino acids (MAAs) are UV-absorbing compounds produced by fungi, algae, lichens, and cyanobacteria when exposed to UV radiation. These compounds have photoprotective and antioxidant functions and have been widely studied for possible use in sunscreens and anti-aging products. This study aims to identify MAA-producing cyanobacteria with potential application in cosmetics. METHODS: A method for the identification of MAAs was developed using ultrahigh-performance liquid chromatography with diode array detection coupled to quadrupole time-of-flight mass spectrometry (UHPLC-DAD/QTOFMS). Chromatographic separation was carried out using a Synergi 4 µ Hydro-RP 80A column (150 × 2,0 mm) at 30°C with 0.1% formic acid aqueous solution + 2 mM ammonium formate and acetonitrile/water (8:2) + 0.1% formic acid as a mobile phase. RESULTS: Out of the 69 cyanobacteria studied, 26 strains (37%) synthesized MAAs. Nine different MAAs were identified using UHPLC-DAD/QTOFMS. Iminomycosporines were the major group detected (7 in 9 MAAs). In terms of abundance, the most representative genera for MAA production were heterocyte-forming groups. Oscilatoria sp. CMMA 1600, of homocyte type, produced the greatest diversity of MAAs. CONCLUSIONS: The UHPLC-DAD/QTOFMS method is a powerful tool for identification and screening of MAAs in cyanobacterial strains as well as in other organisms such as dinoflagellates, macroalgae, and microalgae. The different cyanobacterial genera isolated from diverse Brazilian biomes and environments are prolific sources of MAAs.

Synthesis of molecularly imprinted fluorescent probe based on biomass-derived carbon quantum dots for detection of mesotrione.

A novel fluorescent probe based on molecularly imprinted polymers (MIPs) coupled with carbon quantum dots (CQDs) was fabricated and successfully used for selective recognition of mesotrione. In this probe, the biomass-derived CQDs were prepared through a hydrothermal method using mango peels as carbon source, and the whole synthesis procedure was green without chemical reagents. The CQDs were encapsulated into MIPs by using sol-gel technology. After removal of the template molecule mesotrione, specific binding sites are formed and there is electrostatic attraction between the probe and the template molecule. The synthetic CQDs@MIPs were able to selectively capture the target mesotrione with fluorescence quenching via the specific interaction between mesotrione and the recognition cavities. The probe was used for determination of mesotrione in corn to verify the practicality of the proposed method. The detection limit of mesotrione was 4.7 nmol L-1, and the linear range was 15 nmol L-1 to 3000 nmol L-1. Meanwhile, the recoveries of this method for mesotrione were 91.4-96.2%, and the relative standard deviations (RSDs) were 3.2-6.1%. This work provides a novel research method to synthesize CQDs@MIPs with high selectivity (imprinting factor = 5.6), and which can be used for convenient, rapid recognition and sensitive detection of trace compounds from complex matrices.

LC-MS/MS study of the degradation processes of nitisinone and its by-products.

Nitisinone (2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione, NTBC) was the first synthetically produced triketone herbicide. However, its unsatisfactory herbicidal properties, negative impact on the natural environment and the high cost of synthesis have hindered its commercialization as a plant protection agent. Nevertheless, NTBC has become the medical treatment of choice for a rare hereditary metabolic disease -hepatorenal tyrosinemia. Literature review shows that most research on nitisinone focuses on its medical applications, while there are neither in-depth studies of its stability nor its degradation pathways. Therefore, the aim of our study was to employ liquid chromatography coupled with mass spectrometry (LC-MS/MS) to determine the stability of NTBC in different experimental conditions (pH of solution, temperature, time of incubation, ultraviolet radiation), identify its degradation products and determine the stability of the latter. Electrospray ionization (ESI) in the negative ion mode was used as an ionization method and the analytes were detected by multiple reaction monitoring. We show that nitisinone stability increases with increasing pH of the solution. At pH similar to that of gastric juice in the human stomach, two major products of NTBC degradation are formed: 2-amino-4-(trifluoromethyl)benzoic acid (ATFA) and 2-nitro-4-(trifluoromethyl)benzoic acid (NTFA), which show considerable stability under studied conditions. The results of these studies shed new light on the properties of NTBC, therefore contributing to better understanding of possible risks and benefits of its medical application.

Direct Analysis of Carbonyl Compounds by Mass Spectrometry with Double-Region Atmospheric Pressure Chemical Ionization.

Direct analysis of highly reactive volatile species such as the aliphatic aldehydes as vital biomarkers remains a great challenge due to difficulties in the sample pretreatment. To address such a challenge, we herein report the development of a novel double-region atmospheric pressure chemical ionization mass spectrometry (DRAPCI-MS) method. The DRAPCI source implements a separated structural design that uses a focus electrode to divide the discharge and ionization region to reduce sample fragmentation in the ionization process. Counterflow introduction (CFI) configuration was adopted in the DRAPCI source to reduce background noise, while ion transmission efficiency was optimized through simulating the voltage of the focus electrode and the ion trajectory of the ion source. The limits of detection (LODs) of four carbonyl compounds cyclohexanone, hexanal, heptanal, and octanal by DRAPCI-MS were between 0.1 and 3 µg·m-3, approximately two to eight times lower than those by atmospheric pressure chemical ionization mass spectrometry. Additionally, the DRAPCI-MS method carried out effective in situ analyses of the volatile components in expired milk and the exhaled breath of smokers, demonstrating the DRAPCI-MS as a practical tool to analyze complex mixtures. The DRAPCI-MS method provides a rapid, sensitive, and high-throughput technique in the real-time analysis of gaseous small-molecule compounds.

Comparative study of volatile components from male and female flower buds of Populus × tomentosa by HS-SPME-GC-MS.

The differences of volatile components in male (MFB) and female flower buds (FFB) of Populus × tomentosa were analysed and compared by HS-SPME with GC-MS for the first time. A total of 34 compounds were identified. Two clusters were clearly divided into male and female by hierarchical clustering analysis. Both the male and female flower buds showed methyl salicylate (22.83 and 24.09%, respectively) and 2-hydroxy-benzaldehyde (10.05 and 12.41%, respectively) as the main volatile constituents. The content of 2-cyclohexen-1-one, benzyl benzoate, and methyl benzoate in FFB was remarkably higher than in MFB. In contrast, the content of ethyl benzoate in MFB was greater than that in FFB. The phenomena showed the characteristic differences between MFB and FFB of P. × tomentosa, which enriched the basic studies on dioecious plant.

Effects of the herbicide mesotrione on soil enzyme activity and microbial communities.

Mesotrione (2-[4-(methylsulfonyl)-2-nithobenzoyl]-1, 3-cyclohexanedione) is a selective triketone herbicide that has been widely used in corn production for the past 15 years. However, its potential for risk to soil ecosystems is poorly documented. The present study investigated the soil enzyme activity and soil microbial community responses to a 20 days' mesotrione exposure at doses of 0.1, 1.0 and 5.0 mg/kg. On days 2, 5, 10 and 20, activities of soil ß-glucosidase, urease and acid phosphatase, soil microbe abundances, soil microbial community structure and abundance of the AOA-amoA and AOB-amoA genes were measured. Results showed that activities of urease and acid phosphatase were relatively stable, with no difference found between the mesotrione-treated group and control at the end of exposure. But ß-glucosidase activity was reduced in the 5.0 mg/kg mesotrione treatment. In the 1.0 and 5.0 mg/kg mesotrione-treated soil, abundance of bacteria, fungi and actinomycetes all were reduced. In the 0.1 mg/kg mesotrione-treated soil, only fungi abundance was reduced by the end of the exposure. The analysis of terminal restriction fragment length polymorphism (T-RFLP) revealed soil microbial community structure could be affected by mesotrione at all experimental doses, and microbial diversity declined slightly after mesotrione exposure. Abundance of AOA-amoA and AOB-amoA genes were reduced markedly in 1.0 and 5.0 mg/kg mesotrione-treated soil. The present study suggests that mesotrione at higher doses might induce negative impacts on soil microbes, a finding which merits additional research and which should be accounted for when application of this herbicide is considered.

Quantification of organic solvents in aquatic toys and swimming learning devices and evaluation of their influence on the smell properties of the corresponding products.

Based on the observation that the characteristic odour of inflatable aquatic toys for children is predominantly caused by residues of hazardous organic solvents, the concentrations of cyclohexanone, isophorone and phenol were determined in a selection of 20 products obtained from online suppliers located in Germany. Analytes were extracted with dichloromethane after the addition of non-labelled internal standards, and the volatile fraction was isolated using solvent-assisted flavour evaporation (SAFE). Extracts were then concentrated by Vigreux distillation and analysed by means of gas chromatography with mass spectrometric detection (GC-MS). Furthermore, each sample was evaluated regarding its specific olfactory properties by an expert sensory panel. While some samples did not contain significant amounts of solvents, cyclohexanone concentrations above the lower limit of quantification (LLOQ) were determined in nine samples with six samples containing high concentrations ranging from about 1 to 7 g/kg cyclohexanone. Isophorone concentrations above the LLOQ were observed in eight samples. Thereby, six products contained between 0.3 and 1.6 g/kg isophorone and the remaining two samples contained even about 5 g/kg isophorone, each. Likewise, phenol concentrations exceeded the LLOQ in 14 cases, with four samples containing elevated amounts ranging from about 140 to 280 mg/kg phenol.

Simultaneous determination and method validation of clethodim and its metabolites clethodim sulfoxide and clethodim sulfone in tobacco by LC-MS/MS.

A simple method was developed and validated for the simultaneous determination of clethodim, clethodim sulfoxide, and clethodim sulfone in soil and tobacco by liquid chromatography with tandem mass spectrometry. The three target compounds were extracted from tobacco and soil with acetonitrile, and the extracts were purified using octadecyl silane. The proposed method showed satisfactory linearity (R2 ≥ 0.9973) for the target compounds. The limits of detection and quantitation of the three analytes in all matrices were 0.024-0.06 and 0.08-0.2 mg/kg, respectively. The recovery was tested in blank soil and tobacco leaf samples and calculated to be 74.8-104.4% with relative standard deviations of 1.9-12.1%. The developed method was successfully applied to the analysis of residues of clethodim, clethodim sulfoxide and clethodim sulfone in real soil and tobacco samples. The results indicated that the developed method can meet the requirements for the analysis of trace amounts of all three analytes in soil and tobacco.