Diethyldithiophosphate Research Articles

Combination of a magnetic ionic liquid and magnetic particles for the determination of Pb(II) and Sn(IV) using electrothermal atomic absorption spectrometry

A procedure for the determination of traces of lead and tin by electrothermal atomic absorption spectrometry (ETAAS) after complexation with diethyl dithiophosphate and preconcentration by using a microextraction stage with a magnetic ionic liquid (MIL) supported by ferrite particles is presented. After complexation, the analytes are extracted into the ferrite-supported MIL, the solid particles acting as a carrier to facilitate the separation with a magnet. The analytes are released by treating with acetonitrile and the resulting liquid phase is sampled for the ETAAS measurement. The optimal experimental conditions such as pH, appropriate complexing agent, volumes and doses of all reagents used in the procedure are studied to achieve complete separation of both species. Enrichment factors of 195 and 165 and detection limits of 25 and 72 ng L−1 are obtained for Pb and Sn, respectively. The reliability of the procedure is checked by analyzing six certified reference materials and applied to water samples of different origin, the results being in addition confirmed by standard additions (recoveries 97 ± 7% in all cases).

Development and Validation of a New UFLC-MS/MS Method for the Detection of Organophosphate Pesticide Metabolites in Urine.

To monitor human exposure to pesticides, experts commonly measure their metabolites in urine, particularly dialkyl phosphates (DAPs), which include diethyl phosphate (DEP), Diethyl thiophosphate (DETP), diethyl dithiophosphate (DEDTP), dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP) and dimethyl dithiophosphate (DMDTP)to monitor the metabolites of organophosphates. These DAP metabolites are a urinary biomarker for assessing pesticide exposure and potential health risks. This study presented a new screening method combining ultrafast liquid chromatography with tandem mass spectrometry (UFLC-MS/MS) to detect six DAP metabolites in human urine. The study also compared standard sample extraction methods, namely, liquid-liquid extraction (LLE); quick, easy, cheap, effective, ruggedand safe (QuEChERS); and lyophilization. After a comprehensive analysis of the methods used to extract the analytes, including recovery rate, repeatability and reproducibility, the liquid-liquid extraction (LLE) method was found to be the best. It had a high recovery rate, was easy to handle, required less sample volume and had a short extraction time. Therefore, the LLE method was chosen for further analysis. The results showed excellent performance with high recoveries between 93% and 102%, precise repeatability (RSD) between 0.62% and 5.46% and acceptable reproducibility values (RSD) between 0.80% and 11.33%. The method also had limits of detection (LOD) ranging from 0.0201 ng/mL to 0.0697 ng/mL and limits of quantification (LOQ) ranging from 0.0609 ng/mL to 0.2112 ng/mL. Furthermore, the UFLC-MS/MS method was validated based on the SANTE guidance and successfully analyzed 150 urine samples from farmers and non-farmers. This validated method proved useful for biomonitoring studies focusing on OP pesticide exposure. It offers several advantages, such as a reduced need for samples, chemicals and materials, and a shorter analysis time. The method is sensitive and selective in detecting metabolites in human urine, making it a valuable approach for the practical and efficient assessment of pesticide exposure.

Exposure to non-persistent pesticides and sexual maturation of Spanish adolescent males

BackgroundSeveral non-persistent pesticides are endocrine disrupting chemicals and may impact on sexual maturation. ObjectiveTo examine the association between urinary biomarkers of non-persistent pesticides and sexual maturation in adolescent males in the Environment and Childhood (INMA) Project. MethodsThe metabolites of several pesticides were measured in spot urine samples collected from 201 boys aged 14–17 years, including: 3,5,6-trichloro-2-pyridinol (TCPy), metabolite of chlorpyrifos; 2-isopropyl-4-methyl-6-hydroxypyrimidine (IMPy), metabolite of diazinon; malathion diacid (MDA), metabolite of malathion; diethyl thiophosphate (DETP) and diethyl dithiophosphate, non-specific metabolites of organophosphates; 3-phenoxybenzoic acid (3-PBA) and dimethyl cyclopropane carboxylic acid, metabolites of pyrethroids; 1-naphthol (1-NPL), metabolite of carbaryl; and ethylene thiourea (ETU), metabolite of dithiocarbamate fungicides. Sexual maturation was assessed using Tanner stages, self-reported Pubertal Development Scale, and testicular volume (TV). Multivariate logistic regression was employed to examine associations between urinary pesticide metabolites and the odds of being in Tanner stage 5 of genital development (G5) or pubic hair growth (PH5); stage ≥4 of overall pubertal development, gonadarche, and adrenarche; or having mature TV (≥25 mL). ResultsDETP concentrations>75th percentile (P75) were associated with lower odds of being in stage G5 (OR = 0.27; 95% CI = 0.10–0.70), detectable TCPy with lower odds of gonadal stage≥4 (OR = 0.50; 95% CI = 0.26–0.96), and intermediate detectable MDA concentrations (<P75) with lower odds of adrenal stage≥4 (OR = 0.32; 95% CI = 0.11–0.94). Conversely, detectable concentrations of 1-NPL were associated with higher odds of adrenal stage≥4 (OR = 2.61; 95% CI = 1.30–5.24) but lower odds of mature TV (OR = 0.42; 95% CI = 0.19–0.90). ConclusionExposure to certain pesticides may be associated with delayed sexual maturity in adolescent males.

Use of a simple magnetic material for the determination and speciation of very low amounts of silver and gold

Silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) can be separated of their ions by a magnetic dispersive micro-solid phase extraction procedure using non-functionalised ferrite particles. The separation and speciation are based on careful control of the acidity of the medium, without involving oxidation-reduction processes. Thus, using a small amount of ferrite particles (2 mg for a typical 10 mL sample) which is added to the sample as a suspension, Ag(I) as well as both gold species are retained in the sorbent at pH 4, while AgNPs are retained at pH 8. For the selective retention of AuNPs, ammonium diethyl dithiophosphate is added to the medium and the extraction process is repeated at pH 4. In all cases, the analytes are desorbed by treating the solid phase separated by the magnet with 0.1 mL of a thiourea solution at pH 3 and determined by electrothermal atomization atomic absorption spectrometry. For the measurement of silver, a palladium salt is used as a chemical modifier. This is not required for the determination of gold. The enrichment factor is 97 and the detection limits are 12 and 4 ng L−1 for gold and silver, respectively. The reproducibility is close to 5% for the four analytes studied. The reliability of the procedures is checked by standard additions and by the use of four standard reference materials with certified total silver content. Several water samples are analysed, and speciation results are given.

Highly selective complexation of cadmium from wet phosphoric acid by organic coordination ligands

Recently, the application of organic coordination ligands for the cadmium removal from wet phosphoric acid (WPA) has shown a great interest, and a certain number of commercially available ligands have shown some affinity and selectivity for cadmium. This technic consists in making complexes between cadmium and ligands. It is easy to integrate industrially and does not require significant investment and maintenance overhead; the cost is driven by the organic ligand stability, efficiency and price. However, the challenge still the high cost of ligand and its insufficient world production capacity in comparison to the increasingly demand. The present research article aims to experiment new organic ligands potentially proved in various media for the cadmium removal. The cadmium removal tests from WPA were carried out under the industrial conditions of 25 % (w/w) P2O5, 14 ppm Cd, and 80 °C. A number of 21 organic ligands were carefully selected based on their potential removal of cadmium. The tests were separately performed under the stoichiometric conditions corresponding to a molar ratio R (nLigand/ncd) of 2, and the excess conditions corresponding to a molar ratio R (nLigand/ncd) of 10. Distinctly, the results relatively to R equaling 10 showed significant increase in cadmium removal specifically to DIBDPi (Diisobutyl dithiophosphinate), DEDTP (Diethyl dithiophosphate), ZDDP (Zinc dialkyl dithiophosphinate), TBAI (Tetrabutyl ammonium iodide), Na2CS3 (Sodium trithiocarbonate), and Aliquat 366 (Methyltrioctyl ammonium chloride), with an efficiency of 86 %, 71 %, 68 %, 29 %, 24 %, and 21 %, respectively. The other ligands still showed no affinity for cadmium removal from WPA.

Organophosphate esters exposure in relation to glucose homeostasis and type 2 diabetes in adults: A national cross-sectional study from the national health and nutrition survey

BackgroundExposure to organophosphate esters (OPEs) may be associated with impaired glucose homeostasis and increased risk of type 2 diabetes (T2D) in adolescent. However, the evidence in general population is scarce, especially for glucose homeostasis. We used data from the National Health and Nutrition Examination Survey (NHANES) 1999–2008 and 2011–2012 to investigate the relationship of urinary OPEs with glucose homeostasis and T2D in adults. MethodsA total of 5347 participants aged ≥20 years were included. The exposures were the concentrations of urinary OPEs metabolites [dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP), dimethyl dithiophosphate (DMDTP), diethyl phosphate (DEP), diethyl thiophosphate (DETP), and diethyl dithiophosphate (DEDTP)]. The health outcomes were prevalence of T2D and glucose homeostasis [i.e., fasting glucose, 2-h plasma glucose during a 75-g oral glucose tolerance test (2 h-OGTT), serum insulin, HemoglobinA1c (HbA1c), HOMA-IR, and HOMA-β]. The multivariable linear regression model was used to evaluate the relationship between OPEs and glucose homeostasis. The multivariable binary logistic regression analysis was used to investigate the relationship between OPEs and prevalence of T2D. ResultsThe OPEs compound DMTP was significantly associated with higher levels of serum insulin [β (95%confidence interval, CI) = 0.21 (0.06,0.36), for one unit increase in log2-transformed exposure] and HOMA IR [β (95%CI) = 0.08 (0.02,0.14)], and increased odds of T2D [odds ratio (95% CI) = 1.05 (1.01–1.08)]. Other OPEs were not statistically associated with the serum markers for glucose homeostasis or T2D prevalence. ConclusionOur study found that the OPEs compound DMTP might be associated with impaired glucose homeostasis and may increase the prevalence of T2D in U.S. adults. Further longitudinal or experimental studies are warranted to verify our findings in different populations and different OPEs concentrations.

Combination of supramolecular solvent-based microextraction and ultrasound-assisted extraction for cadmium determination in flaxseed flour by thermospray flame furnace atomic absorption spectrometry

This study describes the development of a new analytical method for cadmium determination in flaxseed flour based on ultrasound-assisted extraction combined with supramolecular preconcentration followed by thermospray flame furnace atomic absorption spectrometry. Cadmium from flaxseed flour was extracted by ultrasound-assisted radiation in acid medium (1.5 mol L−1HNO3) followed by liquid–liquid microextraction of the acid extractwith dodecanoic acid/THF supramolecular solvent using diethyl dithiophosphate as a chelating agent. The limit of detection and the analytical curve range were found to be 0.10 μg L−1 and 0.35 to 20.0 μg L−1, respectively. The cadmium concentration in the flaxseed flours was ranged from 0.11 ± 0.04 to 0.79 ± 0.03 µg g−1. The proposed methodis considered simpler, faster, low-cost, and environmentally friendly compared to procedures currently used for the determination of cadmium based on acid digestion and using graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry.

New sample preparation method to analyse 15 specific and non-specific pesticide metabolites in human urine using LC-MS/MS

This study presents a novel sample preparation method for the determination of both specific and non-specific pesticide metabolites in human urine samples. The method combines a deconjugation step with QuEChERS-based method and solid-phase extraction. In total, 15 pesticide metabolites (diethyl phosphate; diethyl thiophosphate; dimethyl phosphate; diethyl thiophosphate; 2,4-dichlorophenoxyacetic acid; 3-phenoxybenzoic acid; 4-fluoro-3-phenoxybenzoic acid; coumaphos; diethyl dithiophosphate; malathion dicarboxylic acid; p-nitrophenol; cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid; 3,5,6-trichloro-2-pyridinol; N,N-diethyl-3-methylbenzamid and 2-isopropyl-4-methyl-6-hydroxypyrimidine) were separated using liquid chromatography coupled to a mass spectrometer and isotope dilution method for quantitation. The method was validated using recovery tests with recoveries generally ranging from 80 to 120%. Additionally, 20 urine samples collected from South African children were analysed using the presented method. The median levels of pesticide metabolites found in the urine samples ranged from not detected (N,N-diethyl-3-methylbenzamid) to 22.36 µg/g creatinine (dimethyl phosphate). The novel method developed in this study is sensitive, selective, robust and reproducible while also conserving the amount of sample, chemicals, material and time required. Due to the low limits of detection obtained for individual pesticide metabolites, the method is capable of quantifying trace levels of pesticide metabolites in urine, which thus makes it an ideal tool for biomonitoring studies.

Assessment of Organophosphate Pesticides Exposure in Men with Idiopathic Abnormal Semen Analysis: A Cross-Sectional Pilot Study.

Background:Because of the widespread use of organophosphate (OP) pesticides in agriculture, they are major environmental contaminants in developing countries. OP pesticides decrease sperm concentration and affect its quality, viability, and motility. Studies have demonstrated the association between abnormal semen analysis and OP pesticides exposure among the high-risk population. As there is limited data on the percentage of OP pesticides exposure, the study aimed to determine the OP pesticides exposure in Southern Indian men with idiopathic abnormal semen analysis and find the possible source of their OP pesticides exposure.Materials and Methods:In this cross-sectional pilot study, fifty men with idiopathic abnormal semen analysis as cases and fifty men with normal semen analysis as controls were recruited. Detailed history was taken and general and systemic examinations were carried out. OP pesticides exposure was determined by assessment of pseudocholinesterase and acetylcholinesterase levels and urinary OP pesticides metabolites dialkyl phosphate (DAP) consisting of dimethyl phosphate (DMP), diethyl thiophosphate (DETP), and diethyl dithiophosphate (DEDTP).Results:Cases had statistically significantly lower levels of pseudocholinesterase (5792.07 ± 1969.89 vs. 10267.01 ± 3258.58 IU/L) (P=0.006) and acetylcholinesterase [102.90 (45.88-262.74) vs. 570.31 (200.24-975.30) IU/L] (P=0.001) as compared to controls. Cases had a statistically significantly higher percentage of urinary DAP positivity as compared to controls (80 vs. 38%, P<0.0001). Hence, cases had a significantly higher percentage of OP pesticides exposure as compared to controls (20 vs. 4%, P=0.015). OP-exposed cases had significantly higher urinary DETP and DEDTP levels as compared to OP non-exposed cases. Also, urinary DETP and DEDTP levels were significantly negatively associated with sperm concentration, motility, and normal morphology among OP-exposed cases.Conclusion: Southern Indian men with idiopathic abnormal semen analysis had a significantly higher percentage of OP pesticides exposure as compared to men with a normal semen analysis.

The Behaviour of Mixtures of Sodium Iso-Butyl Xanthate and Sodium Di-Ethyl Dithiophosphate during the Flotation of a Cu-Ni-Pt Ore in Degrading Water Quality

The use of mixtures of thiol collectors is reportedly beneficial in sulfide flotation. This is becoming standard practice for many concentrators, but process water recirculation and re-use in flotation circuits may compromise the behaviour of such mixtures owing to changes in physicochemical interactions occurring in the pulp phase as a result of water quality variations. It is expected that changes in the pulp chemistry would in turn affect both the pulp and froth phase phenomena, thereby affecting flotation performance. Thus, this study considers mixtures of thiol collectors, sodium iso-butyl xanthate (SIBX), and sodium di-ethyl dithiophosphate (SEDTP) in degrading water quality. Bench-scale flotation tests were conducted on various molar ratios of the selected thiol collectors under different ionic strengths (0.0242 mol·dm−3 and 0.1212 mol·dm−3) of synthetic plant water. Increasing the ionic strength of synthetic plant water and SEDTP molar ratio resulted in an increase in water, solids, Cu, and Ni recoveries. Cu-Ni grades decreased in increasing SEDTP molar ratios. The highest Cu-Ni grades were obtained in degrading water quality. The increase in water and solids recoveries in increasing SEDTP and ionic strength of plant water is attributed to an increase in froth stability. It can be concluded that the increase in the ionic strength of plant water increased water recoveries and therefore froth stability in parallel with SEDTP’s froth stabilizing effect, thus suggesting an additive interaction on the froth stabilisation effect seen.

Quantification of 16 urinary biomarkers of exposure to flame retardants, plasticizers, and organophosphate insecticides for biomonitoring studies

Chlorinated alkyl and non-chlorinated aryl organophosphate flame retardants (OPFRs) and some brominated flame retardants (FR) were introduced as replacements for polybrominated diphenyl ethers (PBDEs) after PBDEs phase-out in 2004 and 2013. Organophosphorous (OP) insecticides are mainly used in agricultural settings since the Food Quality Protection Act of 1996 phased-out most residential uses of OP insecticides in the United States.Urinary metabolites of FRs and OPs are known exposure biomarkers to FRs and OP insecticides, respectively. For large population-based studies, concurrent quantification of these metabolites using a small urine volume is desirable, but until now was not possible. We developed an analytical approach to quantify in 0.2 mL urine 10 FRs and six OP insecticide metabolites: diphenyl phosphate, bis(1,3-dichloro-2-propyl) phosphate, bis(1-chloro-2-propyl) phosphate, bis(2-chloroethyl) phosphate, dicresyl phosphates, dibutyl phosphate, dibenzyl phosphate, 2,3,4,5-tetrabromobenzoic acid, 2-((isopropyl)phenyl)phenyl phosphate, 4-((tert-butyl)phenyl)phenyl phosphate, dimethyl phosphate, diethyl phosphate, dimethyl thiophosphate, dimethyl dithiophosphate, diethyl thiophosphate, and diethyl dithiophosphate. The method relies on enzymatic deconjugation, automated off-line solid phase extraction, high-performance liquid chromatography, and isotope dilution tandem mass spectrometry. Detection limits ranged from 0.05 to 0.5 ng mL−1, accuracy from 89 to 118%, and imprecision was <10%. .This method is the first to quantify simultaneously trace levels of 16 biomarkers of FRs and OP insecticides in only four drops of urine. We confirmed the method suitability for use in large epidemiological studies to assess background and occupational exposures to these classes of environmental pollutants by analyzing 303 samples collected from the general population and a group of firefighters. FR metabolite and DAPs concentrations in the general population group were lower than in the firefighters group, and within the ranges reported in the U.S. general population and other non-occupationally exposed populations.

Organophosphorus Pesticides Induce Cytokine Release from Differentiated Human THP1 Cells.

Epidemiologic studies link organophosphorus pesticides (OPs) to increased incidence of asthma. In guinea pigs, OP-induced airway hyperreactivity requires macrophages and TNF-α. Here, we determined whether OPs interact directly with macrophages to alter cytokine expression or release. Human THP1 cells were differentiated into macrophages and then exposed to parathion, chlorpyrifos, or diazinon, or their oxon, phosphate, or phosphorothioate metabolites for 24 hours in the absence or presence of reagents that block cholinergic receptors. TNF-α, IL-1β, platelet-derived growth factor, and transforming growth factor-β mRNA and protein were quantified by qPCR and ELISA, respectively. The effects of OPs on NF-κB, acetylcholinesterase, and intracellular calcium were also measured. Parent OPs and their oxon metabolites upregulated cytokine mRNA and stimulated cytokine release. TNF-α release, which was the most robust response, was triggered by parent, but not oxon, compounds. Cytokine expression was also increased by diethyl dithiophosphate but not diethyl thiophosphate or diethyl phosphate metabolites. Parent OPs, but not oxon metabolites, activated NF-κB. Parent and oxon metabolites decreased acetylcholinesterase activity, but comparable acetylcholinesterase inhibition by eserine did not mimic OP effects on cytokines. Consistent with the noncholinergic mechanisms of OP effects on macrophages, pharmacologic antagonism of muscarinic or nicotinic receptors did not prevent OP-induced cytokine expression or release. These data indicate that phosphorothioate OP compounds directly stimulate macrophages to release TNF-α, potentially via activation of NF-κB, and suggest that therapies that target NF-κB may prevent OP-induced airway hyperreactivity.

Assessment of ultrasound-assisted extraction combined with supramolecular solvent-based microextraction for highly sensitive cadmium determination in medicinal plant sample by TS-FF-AAS

A new analytical method exploiting supramolecular solvent-based microextraction (SUPRAS) combined with ultrasound-assisted extraction to preconcentrate cadmium from medicinal plant, with further determination by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS), is proposed. The proposed method is based on the cadmium ultrasound-assisted extraction from Ginkgo biloba L. leaf samples with diluted acid (0.10 mol L−1 HNO3), followed by the metal complexation with diethyl dithiophosphate and preconcentration using a supramolecular solvent composed of inverted hexagonal aggregates of dodecanoic acid arranged in tetrahydrofuran/water medium. The limits of detection (LOD) and quantification (LOQ) were found to be 0.11 μg L−1 and 0.36 μg L−1, respectively. Intraday and interday precision assessed in terms of relative standard deviations (RSD, %) were lower than 8.50% to 0.70, 1.75 and 5.00 μg L−1 cadmium solutions. The efficiency of ultrasound-assisted extraction was comparable to microwave-assisted digestion and the method accuracy was checked by analysis of certified reference material (Tomato Leaves, SRM 1573a). Samples of Ginkgo biloba L. were analyzed and cadmium contents between 0.21 and 0.33 μg g−1 were found, thereby showing clearly the importance of investigating toxic metals in medicinal plants. The proposed method is simple, highly sensitive, environmentally friendly and has great potential to be applied in the quality control of medicinal plants aiming trace cadmium determination.

Determination of Se(IV) concentration via cathodic stripping voltammetry in the presence of Cu(II) ions and ammonium diethyl dithiophosphate

The development of a methodology for the determination of Se(IV) concentration via cathodic stripping voltammetry is described in this work. The methodology is based on the formation of copper selenide (Cu2Se), whose reduction signal at −0.60 V has been used as an analytical response to quantify the Se(IV) concentration in solution. The novelty of our methodology is the study of this system in the presence of a ligand such as ammonium diethyl dithiophosphate (ADTTP), which forms complexes with Cu(II) and Se(IV). The results showed that the presence of ADTTP plays an important role, increasing the sensitivity of the determination by almost a factor of two compared with the methodology in the absence of the ligand. The optimized conditions were pH 1.6 (phosphoric acid, 2.0 × 10−2 mol L−1), CCu(II) = 1.5 mg L−1, CADTTP = 2.0 μmol L−1, Eacc = −0.40 V and tacc = 45 s. The detection and the quantification limits obtained were 0.065 and 0.21 μg L−1, respectively, and linearity was maintained up to 4.0 μg L−1 of Se(IV). The sensitivity was 10.26 nA L μg−1. On the other hand, the relative standard deviation for 15 replicate measurements at 1.0 μg L−1 of Se(IV) was 1.6%. The usefulness of the method was evaluated by determining Se(IV) in two certified reference materials (TMDW and TM−28.4) with relative errors of less than 2.0%. The proposed method was successfully applied to the determination of Se(IV) in spiked tap water and in a liquid pharmaceutical formulation with satisfactory results.The developed methodology presents a low detection limit, good repeatability, selectivity and linear range. Furthermore, the sensibility of the method was achieved by applying a short accumulation time (45 s).

The neurotoxin diethyl dithiophosphate impairs glutamate transport in cultured Bergmann glia cells

Glutamate, the main excitatory neurotransmitter in the vertebrate Central Nervous System, is involved in almost every aspect of brain physiology, and its signaling properties are severely affected in most neurodegenerative diseases. This neurotransmitter has to be efficiently removed from the synaptic cleft in order to prevent an over-stimulation of glutamate receptors that leads to neuronal death. Specific sodium-dependent membrane transporters, highly enriched in glial cells, elicit the clearance of glutamate. Once internalized, it is metabolized to glutamine by the glia-enriched enzyme Glutamine synthetase. Accumulated glutamine is released into the extracellular space for its uptake into pre-synaptic neurons and its conversion to glutamate that is packed into synaptic vesicles completing the glutamate/glutamine cycle. Diverse chemical compounds, like organophosphates, directly affect brain chemistry by altering levels of neurotransmitters in the synaptic cleft. Organophosphate compounds are widely used as pesticides, and all living organisms are continuously exposed to these substances, either in a direct or indirect manner. Its metabolites, like the diethyl dithiophosphate, are capable of causing brain damage through diverse mechanisms including perturbation of neuronal-glial cell interactions and have been associated with attention-deficit disorders and other mental illness.In order to characterize the neurotoxic mechanisms of diethyl dithiophosphate, we took advantage of the well characterized model of chick cerebellar Bergmann glia cultures. A significant impairment of [3H] d-Aspartate transport was found upon exposure to the metabolite. These results indicate that glia cells are targets of neurotoxic substances such as pesticides and that these cells might be critically involved in the associated neuronal death.

Noble metal-free NiS/P-S codoped g-C3N4 photocatalysts with strong visible light absorbance and enhanced H2 evolution activity

Noble metal-free NiS/P-S codoped g-C3N4 (PSCN) nanocomposites were fabricated by combination of thermal copolymerization using ammonium O, O- diethyl dithiophosphate as P-S precursor and ion-exchange precipitation. The optimal H2-generation rate of NiS/PSCN is 30.5μmolh−1, which is 1.9 times higher than that of NiS/pristine g-C3N4. The codoping of P and S into g-C3N4 not only enhances the light harvesting, but also promotes the charge separation. Noble metal-free NiS loaded onto PSCN serves as electron trapping centers and active sites for hydrogen evolution which further enhances the photocatalytic H2 evolution activity of PSCN.

The Impact of Prenatal Organophosphate Pesticide Exposures on Thai Infant Neurodevelopment.

A birth cohort was begun to investigate the levels and sources of pesticide exposure in pregnant women living in Thailand, and to examine the effects of pesticide exposure on infant neurodevelopment at five months of age. Subjects were interviewed using questionnaires regarding their demographic characteristics, educational background, and work and home activities related to pesticide exposures. Spot urine samples were collected at 28 weeks gestation and analyzed by gas chromatography-mass spectrometry to determine maternal metabolite levels of organophosphate pesticides including dimethyl phosphate (DMP); total DEP (diethyl phosphate (DEP), diethyl thiophosphate (DETP), and diethyl dithiophosphate (DEDTP), and total DAP (the sum of all metabolite levels). At five months of age, infant development was evaluated using the Bayley Scales of Infant and Toddler Development-III (Bayley-III). Higher total DEP and total DAP metabolite levels from the mother at 28 weeks’ gestation were significantly associated with reduced motor composite scores on the Bayley-III at five months of age. The total DEP levels were also significantly associated with reduced cognitive composite scores. Prenatal concentrations of maternal urinary metabolites were associated with infant cognitive and motor development. The results of several studies now suggest the need for public health intervention to reduce prenatal pesticide exposures from both agricultural and domestic use.

Understanding the interactions of thiophosphorus collectors with chalcopyrite through DFT simulation

Density functional theory simulations were performed to study the adsorption mechanism of four different thiophosphorus collectors including diethyl dithiophosphate (DEDTPA), diethyl dithiophosphinate (DEDTPI), diethyl monothiophosphate (DEMTPA) and diethyl monothiophosphinate (DEMTPI) on chalcopyrite (100) and (110) surfaces. DFT revealed a major reconstruction of sulfur and metal exposed chalcopyrite (100) surfaces after cleavage. This results into formation of disulfide dimers on the surface and migration of copper and iron inwards with respect to bulk with formation of new FeFe, CuFe and CuCu bonds in the latter after relaxation. Thiophosphorus collectors chemisorb on the sulfur-exposed chalcopyrite (100) surface through formation of a monodentate covalent bond between sulfur atom from the collector polar head and surface-unsaturated sulfur atom. However, the interaction of the collectors with the metal exposed chalcopyrite (100) is through physisorption. The interaction of chalcopyrite (110) surface with thiophosphorus collectors involves bidentate chemical bonding between surface copper and iron atoms and sulfur and/or oxygen atoms of the collector polar-head.

Quantitative analysis of organophosphate insecticide metabolites in urine extracted from disposable diapers of toddlers in Japan.

Epidemiological studies linking insecticide exposure to childhood neurodevelopment have been gaining global attention. Despite the rapid development of the central nervous system in early childhood, studies regarding the biological monitoring of insecticide exposure in diapered children are limited. In this study, we aimed to clarify the concentrations of organophosphate (OP) insecticide metabolites in toddler urine extracted from disposable diapers in Japan. We recruited diapered children from the Aichi regional subcohort participants of the Japan Environment and Children's Study (JECS) at the time of their 18-month checkup. A total of 116 children wore designated disposable diapers overnight, which were then sent as refrigerated cargo. The urine was extracted from the diapers using acetone and analyzed by ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) to determine the concentrations of six dialkyl phosphates (DAPs) (i.e., dimethyl phosphate [DMP], dimethyl thiophosphate [DMTP], dimethyl dithiophosphate [DMDTP], diethyl phosphate [DEP], diethyl thiophosphate [DETP], and diethyl dithiophosphate [DEDTP]). DAP absorption into the diapers was quantified to calculate the urinary DAP concentrations. The DAP recovery using the developed method yielded between 54.2% (DEDTP) and 101.4% (DEP). Within-run precision expressed as the relative standard deviation was between 2.4% and 14.7%, and the between-run precision was between 3.1% and 8.5%. A Bland-Altman analysis confirmed the agreement between the results obtained by the developed method and by the measurements for the corresponding urine without diaper absorption. The geometric means (GM) of urinary DMP, DMTP, DMDTP, DEP, DETP, and total DAPs (ΣDAP) were 3.6, 3.9, 0.9, 6.0, 0.6μg/L, and 137.6 nmol/L, respectively. The GM of DEDTP was not calculated due to its low detection rate. We successfully established a method to measure the DAP concentrations in urine extracted from diapers and this is the first report of these pesticide concentrations in diapered children in Japan.

Technical note: Flotation as a method for concentration of precious metals in electric arc furnace slag

Automobile exhaust catalysts and electronic equipment, for instance, are rich in platinum group metals (PGMs). At the end of their lifecycles catalytic converters are smelted in electric arc furnaces (EAF) for PGM recovery. With approx. 40ppm, PGM depleted EAF slags still contain significantly higher amounts of PGMs than common primary sources (3–10ppm), in contrast to which the material is oxidic or elementary. Until present, there is no utilisation potential for oxidic EAF slag material. Flotation emerged as a possible option for enriching PGMs from EAF slag. Highest enrichment factor (107±9) was determined for Pt by flotation with sodium O,O′-diethyl dithiophosphate (Na-DEDTP) as collector and polypropylene glycol (PPG) as frother. The Pt content of the concentrate was approx. 1500ppm at a recovery rate up to 17±4%.