Enzyme and lateral flow monoclonal antibody-based immunoassays to simultaneously determine spirotetramat and spirotetramat-enol in foodstuffs.

Spirotetramat is employed worldwide to fight insect pests due to its high efficiency. This chemical is quickly metabolized by plants into spirotetramat-enol, so current regulations establish that both compounds must be determined in foodstuffs for monitoring purposes. Nowadays, immunochemical methods constitute rapid and cost-effective strategies for chemical contaminant analysis at trace levels. However, high-affinity binders and suitable bioconjugates are required. In this study, haptens with opposite functionalisation sites were synthesized in order to generate high-affinity monoclonal antibodies. A direct competitive enzyme-linked immunosorbent assay with an IC50 value for the sum of spirotetramat and spirotetramat-enol of 0.1 µg/L was developed using selected antibodies and a novel heterologous bioconjugate carrying a rationally-designed hapten. Studies with fortified grape, grape juice, and wine samples showed good precision and accuracy values, with limits of quantification well below the maximum residue limits. Excellent correlation of results was observed with a standard reference chromatographic method. As a step forward, a lateral flow immunoassay was developed for onsite screening analysis of spirotetramat in wine. This assay was successfully validated according to Regulation 519/2014/EU for semi-quantitative methods at concentrations in line with the legal levels of spirotetramat and spirotetramat-enol in grapes, with a satisfactory false suspect rate below 2%.

Simultaneous determination of spirodiclofen, spiromesifen, and spirotetramat and their relevant metabolites in edible fungi using ultra-performance liquid chromatography/tandem mass spectrometry.

A fast, sensitive, and reliable analytical method was developed and validated for simultaneous identification and quantification of spirodiclofen, spiromesifen, and spirotetramat and their relevant metabolites in edible fungi by ultra-performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS). First, sample extraction was done with acetonitrile containing 1% formic acid followed by phase separation with the addition of MgSO4:NaOAc. Then, the supernatant was purified by primary secondary amine (PSA), octadecylsilane (C18), and graphitized carbon black (GCB). The linearities of the calibrations for all analytes were excellent (R2 ≥ 0.9953). Acceptable recoveries (74.5-106.4%) for all analytes were obtained with good intra- and inter- relative standard deviations of less than 14.5%. The limit of quantification (LOQs) for all analytes was 10 µg kg-1. For accurate quantification, matrix-matched calibration curve was applied to normalize the matrix effect. The results indicated that the method was suitable for detecting the three acaricides and their relevant metabolites in edible fungi.

The chromatographic behaviour of new double-labelled oligodeoxynucleotide probes containing azaphthalocyanine dye as a quencher with respect to evaluation of their purity.

The influence of experimental conditions on chromatographic behaviour of promising oligodeoxynucleotide double-labelled molecular probes containing an azaphthalocyanine macrocycle as a perspective dark quencher was studied. A recently introduced new stationary phase based on styrene-divinylbenzene copolymer was tested. The planar and hydrophobic structure of the azaphthalocyanine is considerably different from those of currently used fluorophores and quenchers. Thus, the most challenging issue was the separation of the double-labelled probe from its main impurity represented by a mono-labelled probe, containing only the azaphthalocyanine macrocycle. The absorbance measurement cannot simply determine this impurity, and its presence fundamentally compromises the biological assay. The commonly used gradient elution was not suitable and isocratic conditions seemed to be more appropriate. The azaphthalocyanine moiety influences the properties of the modified oligodeoxynucleotides substantially, and thus their chromatographic behaviour was determined predominantly by this quencher. Acetonitrile was the preferred organic solvent for the analysis of probes containing the azaphthalocyanine quencher and the effect of ion-pairing reagents was dependent on the probe structure. The temperature seemed to be an effective parameter for fine-tuning of the separation and mass transfer improvement. Generally, our findings could be helpful in method development for purity evaluation of double-labelled oligodeoxynucleotide probes and semipreparative methods.

Bioanalytical assay for the novel TRK inhibitor selitrectinib in mouse plasma and tissue homogenates using liquid chromatography-tandem mass spectrometry.

Selitrectinib is a next generation tropomyosin receptor kinase (TRK) inhibitor developed to overcome acquired resistance to first generation TRK inhibitors. The drug is a cyclic analogue of larotrectinib. An existing bioanalytical assay for larotrectinib was therefore redesigned for selitrectinib. The assay used liquid chromatography-electrospray tandem mass spectrometry in positive selected reaction monitoring mode. Mouse plasma and tissue homogenates of brain, heart, kidney, liver, lung, small intestine, spleen, and testis were pretreated using acetonitrile protein precipitation with larotrectinib added as internal standard. Successful validation using current guidelines was obtained in the range 0.5-1000 ng/ml. Precision was within 5-12% and accuracy within 91-108% for all matrices investigated. The drug was stable in all matrices under the relevant storage conditions. Pharmacokinetics and tissue distribution of selitrectinib were monitored in a pilot study in mice demonstrating the applicability of the presented assay.

New Applications and Analysis of (E)-Azastilbenes in Environmental Samples.

The paper collates and summarizes information on stilbene derivatives, i.e. (E)-azastilbenes, taking into account the new possibilities of their applications, inter alia, in the natural environment. (E)-azastilbenes are biologically active, which is of great importance to humans and the whole ecosystem. As evidenced by a number of studies, they show fungistatic, fungitoxic and, depending on the concentration, estrogenic properties. Due to their properties, (E)-azastilbenes are still of great interest to researchers, who have high hopes for their pharmacological use or the possibility of using them as antiseptics, disinfectants, or preservatives in various products, including the environmental ones. Because of the difficulties with their determination, the study assumes optimal conditions of (E)-azastilbenes extraction from environmental samples and the technique of isotachophoresis is employed for the first time in this type of analysis. The highest recovery values ranging from 83 to 97% were obtained on the aryl extraction columns. The range of linearity of the developed method on the naphthylpropyl column ranged from 5 to 300 µg/mL.

[Determination of spirotetramat and its four metabolites in citrus by ultra-high performance liquid chromatography-triple quadrupole-ion trap mass spectrometry].

A method for the simultaneous determination of spirotetramat and its four metabolites in citrus was developed by ultra-high performance liquid chromatography-triple quadrupole-ion trap mass spectrometry (UPLC-Q TRAP MS).The samples were extracted with acetonitrile and purified by QuEChERS pretreatment.The extracts were detected using an electrospray ionization (ESI) positive ion source under multiple reaction monitoring (MRM) mode, and quantified by matrix matching external standard method.The results showed that spirotetramat and its four metabolites had good linearities in the range of 2-1000 µg/L with correlation coefficients (R2) greater than 0.99.The limits of detection (LODs) of spirotetramat and its four metabolites were in the range of 0.08 to 0.49 µg/kg, while the limits of quantification (LOQ) were in the range of 0.26 to 1.62 µg/kg.The average spiked recoveries were in the range of 94.0% to 98.70%, and the relative standard deviations were 1.1%-5.3%.The results from field trials showed that the contents of the final residues of spirotetramat and its four metabolites in the flesh, peel and whole fruit samples were 5.93-14.20, 11.30-17.86 and 1.30-16.51 µg/kg with the highest recommended dose of 60 mg/kg (active ingredient).The residues in harvested citrus were lower than the national standard maximum residue limit (1.00 mg/kg).The method is simple, rapid and accurate, with a high sensitivity and good separation effect, and the effect of matrix interference can be effectively reduced.The accuracy and precision of this method can meet the requirements of quantitative analysis.The method is suitable for the qualitative and quantitative detection of spirotetramat and its four metabolites in citrus.

Biotransformation of gabapentin in surface water matrices under different redox conditions and the occurrence of one major TP in the aquatic environment.

Laboratory-scale incubation experiments in water/sediment systems were conducted to test the transformation behavior of the anticonvulsant gabapentin (GBP) under different environmental conditions (aerobic, anaerobic, with abiotic controls). GBP was transformed by biological processes as it was eliminated quickly under aerobic conditions (dissipation time 50% of initial concentration (DT50): 2-7 days) whereas no decrease was observed under anaerobic conditions. Measurements via high resolution mass spectrometry (LC-Orbitrap-MS) revealed eight biological transformation products (TPs). Three of them were identified with reference standards (GBP-Lactam, TP186, TP213), while for the other five TPs tentative structures were proposed from information by MS2/MS3 experiments. Furthermore, the quantitatively most relevant TP GBP-Lactam was formed via intramolecular amidation (up to 18% of initial GBP concentration). Incubation experiments with GBP-Lactam revealed a higher stability against biotic degradation (DT50: 12 days) in contrast to GBP, while it was stable under anaerobic and abiotic conditions. Besides GBP, GBP-Lactam was detected in surface water in the µg L-1 range. Finally, GBP and GBP-Lactam were found in potable water with concentrations up to 0.64 and 0.07 µg L-1, respectively. According to the elevated environmental persistence of GBP-Lactam compared to GBP and its presumed enhanced toxicity, we recommend to involve GBP-Lactam into monitoring programs.

Energetic contaminants inhibit plant litter decomposition in soil.

Individual effects of nitrogen-based energetic materials (EMs) 2,4-dinitrotoluene (2,4-DNT), 2-amino-4,6-dinitrotoluene (2-ADNT), 4-amino-2,6-dinitrotoluene (4-ADNT), nitroglycerin (NG), and 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20) on litter decomposition, an essential biologically-mediated soil process, were assessed using Orchard grass (Dactylis glomerata) straw in Sassafras sandy loam (SSL) soil, which has physicochemical characteristics that support "very high" qualitative relative bioavailability for organic chemicals. Batches of SSL soil were separately amended with individual EMs or acetone carrier control. To quantify the decomposition rates, one straw cluster was harvested from a set of randomly selected replicate containers from within each treatment, after 1, 2, 3, 4, 6, and 8 months of exposure. Results showed that soil amended with 2,4-DNT or NG inhibited litter decomposition rates based on the median effective concentration (EC50) values of 1122 mg/kg and 860 mg/kg, respectively. Exposure to 2-ADNT, 4-ADNT or CL-20 amended soil did not significantly affect litter decomposition in SSL soil at ≥ 10,000 mg/kg. These ecotoxicological data will be helpful in identifying concentrations of EMs in soil that present an acceptable ecological risk for biologically-mediated soil processes.

Determination and Safety Assessment of Residual Spirotetramat and Its Metabolites in Amaranth (Amaranthus tricolor) and Soil by Liquid Chromatography Triple-Quadrupole Tandem Mass Spectrometry.

With the purpose of guaranteeing the safe use of spirotetramat and preventing its potential health threats to consumers, a QuEChERS extraction method coupled with LC triple-quadrupole tandem MS was applied in this study to determine residual spirotetramat metabolites in different tissues of amaranth (Amaranthus tricolor) and in soil. The results indicate that the spirotetramat degraded into different types of metabolites that were located in different tissues of amaranth and in soil. B-keto, B-glu, and B-enol were the three most representative degradation products in the leaf of amaranth, and B-glu and B-enol were the two major degradation products found in the stem of amaranth; however, only B-enol was detected in the root of amaranth. B-keto and B-mono were the two products detected in the soil in which the amaranth grew. The cytotoxicity results demonstrate that spirotetramat and its metabolite B-enol inhibited cellular growth, and the toxicity of spirotetramat and its metabolite B-enol exceeded than that of the metabolites B-keto, B-mono, and B-glu. This investigation is of great significance to the safe use of spirotetramat in agriculture.

Dissipation, residues and risk assessment of spirotetramat and its four metabolites in citrus and soil under field conditions by LC-MS/MS.

A modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for the simultaneous determination of spirotetramat and its four metabolite residues in citrus, peel, pulp and soil was developed and validated by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The samples were extracted with acetonitrile (1%, glacial acetic acid, v/v) and purified using primary secondary amine and octadecylsilane. The limit of detection was 0.01-0.13 mg/kg, whereas that of quantification was 0.02-0.40 mg/kg for spirotetramat and its metabolites. The average recoveries of spirotetramat, spirotetramat-enol, spirotetramat-mono-hydroxy, spirotetramat-enol-glucoside and spirotetramat-ketohydroxy in all matrices were 73.33-107.91%, 75.93-114.85%, 76.44-100.78%, 71.46-103.19% and 73.08-105.27%, respectively, with relative standard deviations < 12.32%. The dissipation dynamics of spirotetramat in citrus and soil followed first-order kinetics, with half-lives of 2.3-8.5 days in the three sampling locations. The terminal residues of spirotetramat in four matrices at the three locations were measured below the 1.0 mg/kg maximum residue limit set by China, and residues were found to be concentrated on the peel. The risk assessment of citrus was evaluated using risk quotients. The risk quotient values were found to be significantly <1, suggesting that the risk to human health was negligible when using the recommended doses of spirotetramat in citrus. These results could provide guidance for the safe and proper application of spirotetramat in citrus in China.

[Rapid determination of spirotetramat and its metabolite residues in milk by ultra performance liquid chromatography-tandem mass spectrometry].

A method for the rapid and simultaneous determination of spirotetramat (BYI08330) and its four metabolites in milk was developed with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted with acetonitrile for precipitating proteins, degreased with hexane, and analyzed by UPLC-MS/MS in positive electrospray ionization and multiple reaction monitoring (MRM) mode. Good linear relationships between peak areas and mass concentrations of the analytes were obtained in the range of 0.5-50 µ g/L with correlation coefficients greater than 0.998 (n=6). The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) were 0.05-0.30 µ g/L and 0.17-1.00 µ g/L, respectively. The recoveries at the spiked levels of 1.0, 2.0 and 10 µ g/L were in the range of 80.0%-108.8% with relative standard deviations (RSDs) of 4.8%-15.2% (n=6). The method is fast, sensitive and accurate, and can be used to simultaneously determine BYI08330 and its four metabolites in milk.

The fate of spirotetramat and dissipation metabolites in Apiaceae and Brassicaceae leaf-root and soil system under greenhouse conditions estimated by modified QuEChERS/LC-MS/MS.

The aim of this study was to investigate the dissipation of spirotetramat and its four metabolites (B-enol, B-keto, B-mono and B-glu) in different parts of vegetables belong to the minor crops (Appiacea and Brassicaceae) and soil from cultivation. The challenge of this study was to apply an optimized clean up step in QuEChERS to obtain one universal sorbent for different complex matrices like leaves with high levels of pigments, roots containing acids, sugars, polyphenolls and pigments and soil with organic ingredients. Eight commercial (Florisil, neutral alumina, GCB, PSA, C18, diatomaceous earth, VERDE and ChloroFiltr) and one organic (Chitosan) sorbents were tested. A modified clean up step in QuEChERS methodology was used for analysis. The dissipation of spirotetramat and its metabolites was described according to a first-order (FO) kinetics equation with R2 between 0.9055 and 0.9838. The results showed that the time after 50% (DT50) of the substance degraded was different for soil, roots and leaves, and amounted to 0.2day, 2.8-2.9days and 2.1-2.4days, respectively. The terminal residues of spiroteramat (expressed as the sum of spirotetramat, B-enol, B-glu, B-keto and B-mono) were much lower than the MRLs.

Azaarenes in fine particulate matter from the atmosphere of a Chinese megacity.

Azaarenes (AZAs) are toxicologically relevant organic compounds with physicochemical properties that are significantly different from the well-studied polycyclic aromatic hydrocarbons (PAHs). However, little is known about their concentrations, seasonal variations, fate, and relationship with PAHs in air. This paper reports the temporal variations in the concentrations and composition patterns of AZAs in PM2.5 that was sampled once per 6 days from outdoor air of Xi'an, China from July 2008 to August 2009. The concentrations of the ∑AZAs, quinoline (QUI), benzo[h]quinoline (BQI), and acridine (ACR) in PM2.5 were 213-6441, 185-520, 69-2483, and 10-3544 pg m(-3), respectively. These concentrations were higher than those measured in urban areas of Western Europe. AZA compositional patterns were dominated by BQI and ACR. The high concentration of AZAs, high AZA/related PAH ratio, and the dominance of three-ring AZAs (BQI and ACR) in PM2.5 of Xi'an are all in contrast to observations from Western European and North American cities. This contrast likely reflects differences in coal type and the more intense use of coal in China. The PM2.5-bound concentration of AZA in winter season (W) was higher than during the summer season (S) with W/S ratios of 5.7, 1.4, 4.1, and 13, for ∑AZAs, QUI, BQI, and ACR, respectively. Despite their significantly different physicochemical properties, AZAs were significantly (p < 0.05) positively correlated with their related PAHs and pyrogenic elemental carbon. The changes in AZA concentrations were positively correlated with ambient pressure but negatively correlated with ambient temperature, wind speed, and relative humidity. This trend is similar to that observed for the related PAHs. We conclude that Xi'an and possibly other Chinese cities have higher emission of AZAs into their atmosphere because of the more pronounced use of coal. We also conclude that in spite of differences in physicochemical properties between AZAs and related PAHs, the atmospheric dynamics and relationships with meteorological factors of both compound groups are similar.

Recognition and detection of 8-oxo-rG in RNA using the DNA/OMeRNA chimera probes containing fluorescent adenosine-diazaphenoxazine analog.

Recent studies indicate that oxidative damage to RNA results in dysfunction of translation and eventual pathogenesis. A representative oxidized base in RNA is 8-hydroxyguanosine (8-oxo-rG), however, unlike its DNA counterpart (8-oxo-dG), its role in pathogenesis has not attracted much attention until recently. The 2'-deoxyadenosine derivative with a diazaphenoxazine skeleton at the 6-amino group (Adap) was shown to be selective for 8-oxo-dG in DNA. In this study, the 2'-O-methoxy derivative of Adap (2'-OMeAdap) was designed as a selective molecule for 8-oxo-rG in RNA. 8-Oxo-rG in the homopurine RNA was selectively recognized by the ODN probe incorporating Adap. In contrast, although it was not possible by the Adap-containing ODN prove due to the instability of the corresponding duplex, 8-oxo-rG in homopyrimidine RNA was selectively detected by the 2'-OMeRNA probe incorporating 2'-OMeAdap.

Behaviour of spirotetramat residues and its four metabolites in citrus marmalade during home processing.

The effect of home processing on the residues of spirotetramat and its four metabolites (B-enol, B-glu, B-mono and B-keto) in citrus marmalade is comprehensively investigated in this paper by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). A five-fold recommended dose of spirotetramat was applied to citrus fruit under field conditions and the processing included five steps: washing, peeling, pre-treatment for peel, mixing and boiling. The results showed that spirotetramat was the predominant component detected in unprocessed citrus, accounting for 64%. All the detected residues were primarily deposited on citrus peel, except for B-enol which was also present in the citrus pulp. Washing reduced spirotetramat, B-enol, B-glu and B-keto by 83%, 56%, 41% and 16%, respectively, and pre-treatment of the peel removed between 42% and 68% of the residues. Four compounds were all below the limit of detection after the mixing step. In the final product, only B-keto was detected at the concentration of 0.010 mg kg(-1). After the whole process, the processing factors for spirotetramat, B-enol, B-glu and B-keto were < 0.041, < 0.125, < 0.294 and 0.313, respectively, which indicated that home processing can significantly reduce residues of spirotetramat and its metabolites in citrus marmalade.

Residue evaluation of imidacloprid, spirotetramat, and spirotetramat-enol in/on grapes (Vitis vinifera L.) and soil.

A combination of imidacloprid and spirotetramat effectively controls sucking pests on grapevines. Residues of these insecticides on grapes were evaluated after treatment with spirotetramat 12% + imidacloprid 12% (240 SC) three times at 90 and 180 g a.i. ha(-1). The samples were extracted and purified by QuEChERS method and analyzed by high-performance liquid chromatography with a photodiode array detector (imidacloprid) and gas chromatography mass spectrometry (spirotetramat and its metabolite spirotetramat-enol). Satisfactory results were obtained with ranges of 80.6-98.6% for the recovery, 3.1-10% for the relative standard deviation range, and 9.8-15.6% for the uncertainty. The limits of detection and quantification were 0.015 µg mL(-1) and 0.05 mg kg(-1), respectively. Initial residue concentrations of imidacloprid after the 90 and 180 g a.i. ha(-1) treatments were 0.912 (half-life 11 days) and 1.681 mg kg(-1) (half-life 12.4 days), respectively. For spirotetramat + spirotetramat-enol, the residue concentrations were 1.337 (half-life 5.6 days) and 2.0 mg kg(-1) (half-life 7.6 days) for the 90 and 180 g a.i. ha(-1) treatments, respectively. Spirotetramat degraded faster than spirotetramat-enol. After treatment at 90 g a.i. ha(-1), the initial residues of both insecticides were within European Union maximum residue limits and a 1-day pre-harvest interval (PHI) was adequate for safe consumption of grapes. After treatment at 180 g a.i. ha(-1), the required PHI was 7 day. Therefore, a PHI of 7 day should be used after treatment with imidacloprid and spirotetramat.

An Aza-Cope Reactivity-Based Fluorescent Probe for Imaging Formaldehyde in Living Cells.

Formaldehyde (FA) is a reactive carbonyl species (RCS) produced in living systems that has been implicated in epigenetics as well as in the pathologies of various cancers, diabetes, and heart, liver, and neurodegenerative diseases. Traditional methods for biological FA detection rely on sample destruction and/or extensive processing, resulting in a loss of spatiotemporal information. To help address this technological gap, we present the design, synthesis, and biological evaluation of a fluorescent probe for live-cell FA imaging that relies on a FA-induced aza-Cope rearrangement. Formaldehyde probe-1 (FAP-1) is capable of detecting physiologically relevant concentrations of FA in aqueous buffer and in live cells with high selectivity over potentially competing biological analytes. Moreover, FAP-1 can visualize endogenous FA produced by lysine-specific demethylase 1 in a breast cancer cell model, presaging the potential utility of this chemical approach to probe RCS biology.

Characterizations of organic compounds in diesel exhaust particulates.

To characterize how the speed and load of a medium-duty diesel engine affected the organic compounds in diesel particle matter (PM) below 1 µm, four driving conditions were examined. At all four driving conditions, concentration of identifiable organic compounds in PM ultrafine (34-94 nm) and accumulation (94-1000 nm) modes ranged from 2.9 to 5.7 µg/m(3) and 9.5 to 16.4 µg/m(3), respectively. As a function of driving conditions, the non-oxygen-containing organics exhibited a reversed concentration trend to the oxygen-containing organics. The identified organic compounds were classified into eleven classes: alkanes, alkenes, alkynes, aromatic hydrocarbons, carboxylic acids, esters, ketones, alcohols, ethers, nitrogen-containing compounds, and sulfur-containing compounds. At all driving conditions, alkane class consistently showed the highest concentration (8.3 to 18.0 µg/m(3)) followed by carboxylic acid, esters, ketones and alcohols. Twelve polycyclic aromatic hydrocarbons (PAHs) were identified with a total concentration ranging from 37.9 to 174.8 ng/m(3). In addition, nine nitrogen-containing polycyclic aromatic compounds (NPACs) were identified with a total concentration ranging from 7.0 to 10.3 ng/m(3). The most abundant PAH (phenanthrene) and NPACs (7,8-benzoquinoline and 3-nitrophenanthrene) comprise a similar molecular (3 aromatic-ring) structure under the highest engine speed and engine load.

Toxicological effects of soil contaminated with spirotetramat to the earthworm Eisenia fetida.

The aim of this study was to evaluate the potential toxicity of spirotetramat to the earthworm Eisenia fetida in a natural soil environment. Many biochemical markers, viz., superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione S-transferase (GST), cellulase, and malondialdehyde (MDA) contents were measured after exposure to 0.25, 1.25, and 2.5mgkg(-1) for 2, 7, 14, 21, and 28days. In addition, the comet assay was performed on earthworm coelomocytes to assess the level of genetic damage. The results demonstrate that the SOD activity and MDA content were significantly stimulated by the highest dose (2.5mgkg(-1)) of spirotetramat for the entire period of exposure. The activities of CAT and POD increased significantly by 2d and 21d, respectively, but the activities of both were significantly inhibited after prolonged exposure (28d). After an initial increase on the 2nd day, the cellulase activity in the high-dose treatment group was significantly inhibited for the entire remaining exposure period. The comet assay results demonstrate that spirotetramat (⩽2.5mgkg(-1)) can induce low and intermediate degrees of DNA damage in earthworm coelomocytes. The results indicate that spirotetramat may pose potential biochemical and genetic toxicity to earthworms (E. fetida), and this information is helpful for understanding the ecological toxicity of spirotetramat on soil invertebrate organisms.

Alkaline hydrolysis of hexahydro-1,3,5-trinitro-1,3,5-triazine: M06-2X investigation.

Alkaline hydrolysis mechanism of possible environmental contaminant RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) was investigated computationally at the PCM(Pauling)/M06-2X/6-311++G(d,p) level of theory. Results obtained show that the initial deprotonation of RDX by hydroxide leads to nitrite elimination and formation of a denitrated cyclohexene intermediate. Further nucleophilic attack by hydroxide onto cyclic CN double bond results in ring opening. It was shown that the presence of hydroxide is crucial for this stage of the reaction. The dominant decomposition pathway leading to a ring-opened intermediate was found to be formation of 4-nitro-2,4-diazabutanal. Hydrolytic transformation of its byproduct (methylene nitramine) leads to end products such as formaldehyde and nitrous oxide. Computational results are in a good agreement with experimental data on hydrolysis of RDX, suggesting that 4-nitro-2,4-diazabutanal, nitrite, formaldehyde, and nitrous oxide are main products for early stages of RDX decomposition under alkaline conditions.