Alkyl Phosphates Research Articles

Recent advances in the synthesis of 4′-truncated nucleoside phosphonic acid analogues

The synthesis of five series of 4′-truncated nucleoside phosphonic acid analogues is discussed in this review: (1) 4′-truncated furanose nucleoside phosphonic acid analogues; (2) 4′-truncated pyrrolidine nucleoside phosphonic acid analogues; (3) 4′-truncated carbocyclic nucleoside phosphonic acid analogues; (4) 4′-truncated isoxazole nucleoside phosphonic acid analogues; (5) 4′-truncated miscellaneous nucleoside phosphonic acid analogues. Five different ways are used to make the phosphonate moiety: (i) Michaelis-Arbuzov reaction of RX (X = Br, I, OTf) with trialkyl phosphate; (ii) Lewis acid catalyzed Michaelis-Arbuzov reaction of glycoside with trialkyl phosphite; (iii) nucleophilic addition of a dialkyl phosphite to a carbonyl group; (iv) direct coupling reaction with amino alkyl phosphonate; (v) de novo synthesis of phosphonated-isoxazole and 1,3-dioxolane heterocycles from phosphonated starting materials. Their biological activity results are briefly discussed.

Prenatal exposure to organophosphate pesticides and risk-taking behaviors in early adulthood

IntroductionPrevious studies show evidence for associations of prenatal exposure to organophosphate (OP) pesticides with poorer childhood neurodevelopment. As children grow older, poorer cognition, executive function, and school performance can give rise to risk-taking behaviors, including substance abuse, delinquency, and violent acts. We investigated whether prenatal OP exposure was associated with these risk-taking behaviors in adolescence and young adulthood in a Mexican American cohort.MethodsWe measured urinary dialkyl phosphates (DAPs), non-specific metabolites of OPs, twice (13 and 26 weeks gestation) in pregnant women recruited in 1999–2000 in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, a birth cohort set in a primarily Latino agricultural community in the Salinas Valley, California. We followed up children throughout their childhood and adolescence; at the 18-year visit, adolescent youth (n = 315) completed a computer-based questionnaire which included questions about substance use, risky sexual activity, risky driving, and delinquency and police encounters. We used multivariable models to estimate associations of prenatal total DAPs with these risk-taking behaviors.ResultsThe prevalence of risk-taking behaviors in CHAMACOS youth ranged from 8.9% for smoking or vaping nicotine to 70.2% for committing a delinquent act. Associations of total prenatal DAPs (geometric mean = 132.4 nmol/L) with risk-taking behavior were generally null and imprecise. Isolated findings included a higher risk for smoking or vaping nicotine within the past 30 days (relative risk [RR] per 10-fold increase in prenatal DAPs = 1.89, 95% CI: 1.00, 3.56) and driving without a license (RR = 1.74, 95% CI: 1.25, 2.42). There were no consistent differences by sex or childhood adversity.DiscussionWe did not find clear or consistent evidence for associations of prenatal OP exposure with risk-taking behaviors in adolescence/early adulthood in the CHAMACOS population. Our small sample size may have prevented us from detecting potentially subtle associations of early life OP exposure with these risk-taking behaviors.

Quantitative analysis of organophosphate pesticides and dialkylphosphates in duplicate diet samples to identify potential sources of measured urinary dialkylphosphates in Japanese women

Increased levels of dialkylphosphates (DAP) in maternal urine are associated with a variety of adverse developmental outcomes in children. Although urinary DAP levels are usually considered to be a marker of exposure to organophosphate (OP) pesticides, excretion of DAP may also increase by ingesting preformed DAP. To date, no study has quantitatively assessed the possible contribution of the dietary intake of preformed DAP and OP pesticides to urinary levels of DAP. Therefore, we aimed to estimate the levels of 6 DAPs and 84 OP pesticides in duplicate diet samples and urine samples collected from 73 women living in urban areas of Japan in 2018. DAP and OP pesticides were detected in 94% and 45% of diet samples, while DAP was detected in 100% of urinary samples, respectively. The average daily intake of preformed DAP was significantly higher than that of parent OP pesticides in our participants. Dimethylphosphate and diethylphosphate were predominant in the preformed DAP, and the estimated average daily intake of total amount of DAP was 78.3 nmol. Fruits and vegetables were the major dietary sources of DAP. Dietary intake of DAP was positively associated with urinary DAP levels, suggesting that a considerable amount of urinary DAP was derived from ingesting preformed DAP. Our results show that attributing urinary DAP levels exclusively to OP pesticide exposure would result in a substantial overestimation of the exposure level. Therefore, the urinary levels of DAP may not be suitable for evaluating OP pesticide exposure in the general urban population.

Methylation patterns of the CDKN2B and CDKN2A genes in an indigenous population exposed to pesticides.

The INK4-ARF locus includes the CDKN2B and CDKN2A genes and is functionally relevant in the regulation of both cell proliferation and senescence. Studies have reported modifications of DNA methylation in this locus by exposure to environmental contaminants including pesticides; however, until now, specific methylation profiles have not been reported in genetically conserved populations exposed to occupational pesticides. The aim of this study was to determine the methylation profiles of the CDKN2B and CDKN2A genes in a genetically conserved population exposed to pesticides. A cross-sectional and analytical study was carried out in 190 Huichol indigenous persons. Information related to pesticide exposure, diet and other variables were obtained through the use of a structured questionnaire. Blood and urine samples were collected for methylation test and dialkylphosphates (DAP) determination, respectively. DNA methylation was measured by the pyrosequencing of bisulfite-treated DNA and DAP concentrations by gas chromatography-tandem mass spectrometry (GC/MS). The most frequent metabolite in the population was dimethylthiophosphate. The farmer group presented a higher methylation percentage of CDKN2B than the non-farmer group, but no differences in CDKN2A were observed between groups. A positive correlation between methylation of CpG site 3 of CDKN2B and time working in the field was observed in the farmer group. An association between methylation percentage of CDKN2B and age was also observed in the non-farmer group. These results suggest that pesticide exposure and exposure time in Huichol indigenous individuals could modify the methylation pattern of the CDKN2B gene.

The pervasive impact of critical fluctuations in liquid-liquid extraction organic phases.

Liquid-liquid extraction is an essential chemical separation technique where polar solutes are extracted from an aqueous phase into a nonpolar organic solvent by amphiphilic extractant molecules. A fundamental limitation to the efficiency of this important technology is third phase formation, wherein the organic phase splits upon sufficient loading of polar solutes. The nanoscale drivers of phase splitting are challenging to understand in the complex hierarchically structured organic phases. In this study, we demonstrate that the organic phase structure and phase behavior are fundamentally connected in a way than can be understood with critical phenomena theory. For a series of binary mixtures of trialkyl phosphate extractants with linear alkane diluents, we combine small angle x-ray scattering and molecular dynamics simulations to demonstrate how the organic phase mesostructure over a wide range of compositions is dominated by critical concentration fluctuations associated with the critical point of the third phase formation phase transition. These findings reconcile many longstanding inconsistencies in the literature where small angle scattering features, also consistent with such critical fluctuations, were interpreted as reverse micellar-like particles. Overall, this study shows how the organic phase mesostructure and phase behavior are intrinsically linked, deepening our understanding of both and providing a new framework for using molecular structure and thermodynamic variables to control mesostructure and phase behavior in liquid-liquid extraction.

Determination of the Characteristics of the Molecular Structure of Trialkyl Phosphates by the Joint Application of Electronic Ionization Mass Spectra with Registration of Positive Ions and Negative Ions of Resonance Coupling

Trialkylphosphates are of considerable interest from the military-chemical point of view as precursors of highly toxic organophosphorus toxicants, possible products of their decontamination, complexing agents in processes of reprocessing of used nuclear fuel, etc. Meanwhile, the development of ways to identify these substances is still in its infancy. In addition, trialkylphosphates are an interesting subject for the search of a solution to the analytical problem of establishing the structure of O-alkyl fragments in molecules of M(O) (OR) n esters of multibasic acids, where M is the central atom (central core), n is the basicity of the acid, R are alkyl radicals with an unknown and in general case different number of carbon atoms in each of them. No general solution to this problem could be found in the book sources. The aim of this work is to develop an algorithm for in-depth identification of trialkyl phosphates, which includes establishing the belonging of the investigated substance to this class, as well as a general and reliable method for determining the number of carbon atoms in each of the O-alkyl radicals of the investigated substances. On the basis of the revealed regularities of the decay of positive molecular ions of trialkyl phosphates, as well as negative ions of resonant capture of electrons of the same compound obtained under conditions of electron ionization, an algorithm for in-depth identification of trialkyl phosphates is proposed, which includes establishing the belonging of the investigated substance to this class, as well as a general and reliable method determining the number of carbon atoms in each of the O-alkyl radicals of the substance molecule

Investigation of the Phase Splitting Behaviour of U(VI) and Th(IV) loaded Trialkyl Phosphate Solvents in the Absence of Aqueous Phase

AbstractTri‐n‐butyl phosphate (TBP), a universally recognized solvent, has got lesser organic phase splitting or third phase formation tendency during the extraction of U(VI) as compared to tetravalent metal ions. Thus, the lighter members of trialkyl phosphates (TalP) (i. e.) tri‐n‐propyl phosphate (TPP) and triethyl phosphate (TEP) having higher third phase formation tendency would provide an opportunity to comprehend the aggregation of U(VI) loaded TalP solvents. As the above lighter TalPs exhibit higher aqueous solubility, the conventional measurement of third phase limit or Limiting Organic Concentration (LOC) by mixing organic and aqueous phases cannot be employed for the investigation of U(VI) third phase in TalPs. This has led to the development of a novel method to examine U(VI) third phase in aqueous soluble TalP solvent systems without aqueous feed solution. After validation, the newly developed method has then been utilized to determine the LOC for 1.1 M TPP in n‐alkane. The variation of extractant structure, diluent chain length, nature of metal ion and temperature on the third phase of 1.1 M TalP systems has been evaluated along with their molecular level understanding using Dynamic Light Scattering.

Organophosphate pesticide exposure as a risk factor for attempted suicide in Cape Town, South Africa: A case-control study

Pesticides are a commonly used agent for suicide in many Low- and Middle-Income countries (LMICs). However, accumulating evidence suggests that exposure to organophosphate (OP) pesticide may also increase the risk of suicide. We conducted a hospital-based case-control study to investigate whether prior household, garden or occupational OP exposure were associated with attempted suicide using conditional logistic regression modeling. Participants who attempted suicide with any means and were admitted to two Western Cape Province hospitals in South Africa were compared to a sample of controls matched by age, sex and time of admission with unrelated conditions, between August 2015 and August 2017. The means of attempted suicide was not recorded. OP exposure was determined by dialkyl phosphate (DAP) metabolites detected in hair and by environmental and occupational history. Approximately 85% of participants reported using pesticides in the home or garden and 15% of participants reported current or past occupational exposure while working on a farm. Attempted suicide was not associated with reported home or garden OP use (Odds ratio [OR] = 0.59, 95%CI 0.33–1.04), hair DAP metabolites (OR = 1.00, 95%CI 0.98–1.02) or current or past agricultural work (OR = 1.08, 95%CI 0.62–1.87), but was associated with hazardous drinking and unemployment with no household income. We found no evidence that attempted suicide was associated with environmental or occupational pesticide use in an urban South African population attending an emergency center.

Transition-Metal-Free Addition of Dialkyl Phosphites to Phthalazin-2-ium Bromide: Synthesis of α-Aminophosphonate Analogues.

α-Aminophosphonate analogues containing a phthalazine skeleton were efficiently obtained by a new transition-metal-free addition of dialkyl phosphites to phthalazin-2-ium bromide under mild conditions. A mechanistic study using isotope labeling and radical inhibition experiment revealed that the present transformation passes through a nucleophilic addition of dialkyl phosphates, rather than an insertion of P-H to carbenes.

Urinary Organophosphate Metabolites and Metabolic Biomarkers of Conventional and Organic Farmers in Thailand.

Organophosphate (OP) pesticides are used by most farmers to remove insects and to increase productivity; however, questions remain on the long-term health impacts of their use. This study assessed the relationship between OP biomarker levels and metabolic biomarker parameters. Conventional farmers (n = 213) and organic farmers (n = 225) were recruited, interviewed, and had physical health examinations. Serum glucose and lipid profiles, triglycerides, total cholesterol, high-density lipoproteins (HDL), and low-density lipoproteins (LDL) were measured. The average age, gender, education, and self-reported agricultural work time, work in second jobs, smoking status, alcohol consumption, insecticide use at home, home location near farmlands and years of pesticide use were significantly different between the conventional and organic farmers. The urinary OP metabolite levels were also significantly different between the two groups. With an increase in urinary diethyl phosphate, dimethyl phosphate and dialkyl phosphate metabolites, the total cholesterol, LDL and HDL, were significantly increased for all farmers after controlling for age, gender, alcohol consumption, years of pesticide use, and home location near farmlands. The results are consistent with our previous studies which suggests that pesticide usage, especially organophosphates, may increase the risk of cardiovascular disease and stroke among Thai farmers.

Prenatal Exposure to Nonpersistent Chemical Mixtures and Fetal Growth: A Population-Based Study.

Background:Prenatal exposure to mixtures of nonpersistent chemicals is universal. Most studies examining these chemicals in association with fetal growth have been restricted to single exposure models, ignoring their potentially cumulative impact.Objective:We aimed to assess the association between prenatal exposure to a mixture of phthalates, bisphenols, and organophosphate (OP) pesticides and fetal measures of head circumference, femur length, and weight.Methods:Within the Generation R Study, a population-based cohort in Netherlands (), urinary concentrations of 11 phthalate metabolites, 3 bisphenols, and 5 dialkylphosphate (DAP) metabolites were measured at , 18–25, and of gestation and averaged. Ultrasound measures of head circumference, femur length, and estimated fetal weight (EFW) were taken at 18–25 and of gestation, and measurements of head circumference, length, and weight were performed at delivery. We estimated the difference in each fetal measurement per quartile increase in all exposures within the mixture with quantile g-computation.Results:The average EFW at 18–25 wk and was 369 and , respectively, and the average birth weight was . Higher exposure was associated with smaller fetal and newborn growth parameters in a nonlinear fashion. At 18–25 wk, fetuses in the second, third, and fourth quartiles of exposure (Q2–Q4) had [, ], (, ), and (, 1) lower EFW compared with those in the first quartile (Q1). A similar dose–response pattern was observed at , but all effect sizes were smaller, and no association was observed comparing Q4 to Q1. At birth, we observed no differences in weight between Q1–Q2 or Q1–Q3. However, fetuses in Q4 had (, 76) lower birth weight in comparison with those in Q1. Results observed at 18–25 and were similar for femur length; however, no differences were observed at birth. No associations were observed for head circumference.Discussion:Higher exposure to a mixture of phthalates, bisphenols, and OP pesticides was associated with lower EFW in the midpregnancy period. In late pregnancy, these differences were similar but less pronounced. At birth, the only associations observed appeared when comparing individuals from Q1 and Q4. This finding suggests that even low levels of exposure may be sufficient to influence growth in early pregnancy, whereas higher levels may be necessary to affect birth weight. Joint exposure to nonpersistent chemicals may adversely impact fetal growth, and because these exposures are widespread, this impact could be substantial. https://doi.org/10.1289/EHP9178

Urinary Concentrations of Dialkylphosphate Metabolites of Organophosphate pesticides in the Study of Asian Women and their Offspring’s Development and Environmental Exposures (SAWASDEE)

BackgroundMeasurements of urinary dialkyl phosphate (DAP) metabolites are often used to characterize exposures to organophosphate (OP) insecticides; however, some challenges to using urinary DAP metabolites as an exposure measure exist. OP insecticides have short biological half-lives with measurement in a single urine sample typically only reflecting recent exposure within the last few days. Because of the field staff and participant burden of longitudinal sample collection and the high cost of multiple measurements, typically only one or two urine samples have been used to evaluate OP insecticide exposure during pregnancy, which is unlikely to capture an accurate picture of prenatal exposure. MethodsWe recruited pregnant farmworker women in Chom Thong and Fang, two districts of Chiang Mai province in northern Thailand (N = 330) into the Study of Asian Women and their Offspring’s Development and Environmental Exposures (SAWASDEE) from 2017 to 2019. We collected up to 6 serial urine samples per participant during gestation and composited the samples to represent early, mid, and late pregnancy. We measured concentrations of urinary DAP metabolites in the composited urine samples and evaluated the within- and between-participant variability of these levels. We also investigated predictors of OP insecticide exposure. ResultsDAP metabolite concentrations in serial composite samples were weakly to moderately correlated. Spearman correlations indicated that composite urine samples were more highly correlated in Fang participants than in Chom Thong participants. The within-person variances (0.064–0.65) exceeded the between-person variances for DETP, DEP, ∑DEAP, DMP, DMTP, ∑DMAP, ∑DAP. The intraclass correlations (ICCs) for the volume-based individual metabolite levels (ng/mL) ranged from 0.10 to 0.66. For ∑DEAP, ∑DMAP, and ∑DAP the ICCs were, 0.47, 0.17, 0.45 respectively. We observed significant differences between participants from Fang compared to those from Chom Thong both in demographic and exposure characteristics. Spearman correlations of composite samples from Fang participants ranged from 0.55 to 0.66 for the ∑DEAP metabolite concentrations in Fang indicating moderate correlation between pregnancy periods. The ICCs were higher for samples from Fang participants, which drove the overall ICCs. ConclusionsCollecting multiple (∼6) urine samples during pregnancy rather than just 1 or 2 improved our ability to accurately assess exposure during the prenatal period. By compositing the samples, we were able to still obtain trimester-specific information on exposure while keeping the analytic costs and laboratory burden low. This analysis also helped to inform how to best conduct future analyses within the SAWASDEE study. We observed two different exposure profiles in participants in which the concentrations and variability in data were highly linked to the residential location of the participants.

Hydrodynamic Properties of Tris(2-methylbutyl) Phosphate and Tri-n-alkyl Phosphates in n-Dodecane – A Comparative Investigation between Unirradiated and Gamma Irradiated Solvent Systems

ABSTRACT The physicochemical parameters of tris(2-methylbutyl) phosphate (T2MBP), a molecule possessing the essential characteristics required to be considered as a promising extractant in the solvent extraction stage of fast reactor fuel reprocessing, have been evaluated in the present study. In this context, the density, viscosity and interfacial tension (IFT), which are considered to be few among the important solvent selection criteria prior to its deployment in the plant scale have been measured for T2MBP in n-dodecane (n-DD) based systems. Similar studies have been performed with its straight chain isomer, tri-n-amyl phosphate (TAP) as well as the widely utilized commercial extractant, tri-n-butyl phosphate (TBP) so as to emphasize on the structural effects. Though the trends on the physicochemical behaviour of TBP based systems (temperature and ligand concentration effects) are well known in the literature, the data on TBP have been generated in the present work for comparison with the T2MBP results under similar experimental conditions. Solutions of trialkyl phosphates (TalP) in n-DD of different concentrations have been used to generate the data on the variation of density, IFT and viscosity with the change in the ligand concentration. In addition, the transformation in their properties has been assessed after subjecting the solvents to various levels of gamma absorbed doses. Overall, it has been observed that there was no significant variation in the density of the irradiated TalPs; however, there was a significant rise in the viscosity and reduction in the IFT of the TalP samples upon irradiation. The data on the Gibbs energy change of activation of various 1.1 M TalP/n-DD solutions have been generated by fitting their respective dynamic viscosity value as a function of temperature using Andrade’s equation. Moreover, from the IFT value, the parameters relating to the interfacial activity of TalP/n-DD solutions have been determined using the Szyszkowski adsorption isotherm.

Studies on the aggregation behavior of mineral acid and Zr(IV) loaded Tris(2-methylbutyl) phosphate and tri-n-alkyl phosphate systems using small angle neutron scattering

ABSTRACT The third-phase phenomenon has been observed during the extraction of certain metal ions and mineral acids by 30% (v/v) tri-n-butyl phosphate (TBP) in n-dodecane in the solvent extraction stage of spent nuclear fuel reprocessing. At molecular scale, it has been predicted that the self-organization of the extracted polar species to form reverse micelle-like structure is primarily responsible for third-phase formation. In this regard, the aggregation behavior of solutions of three different trialkyl phosphates in n-alkanes loaded with monoprotic mineral acids (HClO4, HCl and HNO3) as well as tetravalent Th and Zr has been evaluated using Small Angle Neutron Scattering (SANS). The aggregation of TBP has been compared with two of its five carbon analogues i.e. tri-n-amyl phosphate (TAP) and tris(2-methylbutyl) phosphate (T2MBP), which have gained its attention in the course of development of an alternate extractant for the reprocessing process. The effects of trialkyl phosphate structure, diluent chain length and extractant concentration on the aggregation have been emphasized. The contribution of the polar (anionic and cationic component) as well as the apolar part of the reverse micelle toward the phase splitting behavior has been analyzed. The SANS results are in agreement with the earlier reported solvent extraction data.

Temporal variability of organophosphate insecticide metabolites over one year in Chinese adults

Organophosphate (OP) insecticides widely used worldwide are a class of non-persistent pollutants with a short biological half-life. Most OP insecticides are rapidly metabolized in the human body to six dialkyl phosphate metabolites (DAPs), of which urinary concentrations are usually used to assess OP insecticide exposures. In this study, to understand the reliability of a single measurement of OP insecticide metabolites in representing a true longer-term average exposure, we investigated the temporal variability of urinary DAPs over one year in 114 Chinese adults aged 18–30. The detection rates for all six DAP metabolites exceeded 98%. The intraclass correlation coefficients (ICCs) of DAPs indicated poor (ICC < 0.4) to fair (ICC = 0.4–0.75) reproducibility in spot urine samples over one week, month, or year. Log-transformed DAP metabolites requested 2–12 spot urine samples per subject to offer a reliable estimate of OP insecticide exposures over several months or one year. The sensitivity and specificity for predicting subjects with the one-year average OP insecticide exposure in the highest tertile with one, two, or three urine samples varied from 0.25 to 0.991, 0.491 to 0.966, respectively. We recommend at least 3 spot urine samples for the assessment of one-year OP insecticide exposure by using log-transformed DAPs. This study offers a reference for an appropriate evaluation of a relatively long-period exposure to OP insecticides in biomonitoring and epidemiological studies.

Combining Experiments and Theoretical Calculations to Investigate the Intercalation Behavior of Bis(trifluoromethanesulfonimide) Anion into Graphite Electrodes from Alkyl Phosphates.

In dual-ion batteries (DIBs) utilizing organic electrolyte solutions, the combinations of electrolyte salt and solvent serve as a determiner of the electrochemical performance of graphite electrode partially because solvent participates in the anion intercalation procedure. In this case, every solvated-anion@graphite intercalation compound possesses the characteristic intercalated gallery height. However, in Li/graphite DIBs with concentrated LiTFSI (lithium bis(trifluoromethanesulfonimide))-alkyl phosphates (ca. trimethyl, triethyl, tripropyl, tributyl phosphate) solutions, solvated-TFSI-@graphite intercalation compounds have the nearly identical intercalated gallery height of about 0.803 nm, which may be mainly attributed to both the big size of TFSI- anion and the rigid PO4 framework of these alkyl phosphate solvents.

Synergistic inhibition of cerium and alkyl phosphate composite adlayer on pitting corrosion of Al–Mg–Si aluminium alloy

ABSTRACT The nucleation, propagation, and rehabilitation of pitting corrosion of Al–Mg–Si Aluminium alloy (AA6063) are studied in 3%NaCl solution by using electrochemical noise measurement. It shows that the composite film composed of sequent precipitation of ceria and 1-tetradecylphosphonic acid (DPA) presents the best pitting corrosion resistance compared with the independent ceria conversion film or self-assembling DPA film. XPS and microscopic Raman spectra confirmed that Ceria film is an excellent interlayer for the self-assembling of alkyl phosphate on the intermetallic particles in Al alloy. The anti-corrosion performance of Cerium oxides and DPA composite film is totally dependent on the deposition sequence. Prior deposition of ceria and then DPA film can increase the hydrophilicity of Al matrix and AlFeSi intermetallic particles, further promoting the self-assembling of upper DPA molecules, thus dramatically improving the overall and pitting corrosion resistance of AA6063. This could be attributed to the synergistic effects between the upper DPA film and underlying Ce conversion film. On the contrary, Prior assembly of DPA and then deposition of ceria, may significantly degrade their inhibition efficiency.

LC-HRMS screening of per- and polyfluorinated alkyl substances (PFAS) in impregnated paper samples and contaminated soils

High per- and polyfluorinated alkyl substance (PFAS) concentrations have been detected in agricultural soils in Southwest Germany. Discharges of PFAS-contaminated paper sludge and compost are suspected to be the cause of the contamination. Perfluorinated carboxylic acids (PFCAs) have been detected also in groundwater, drinking water, and plants in this area. Recently, previously unknown compounds have been identified by high-resolution mass spectrometry (HRMS). Major contaminants were polyfluorinated dialkylated phosphate esters (diPAPs) and N-ethyl perfluorooctane sulfonamide ethanol–based phosphate diester (diSAmPAP). In this study, HRMS screening for PFAS was applied to 14 soil samples from the contaminated area and 14 impregnated paper samples which were from a similar period than the contamination. The paper samples were characterized by diPAPs (from 4:2/6:2 to 12:2/12:2), fluorotelomer mercapto alkyl phosphates (FTMAPs; 6:2/6:2 to 10:2/10:2), and diSAmPAP. In soil samples, diPAPs and their transformation products (TPs) were the major contaminants, but also FTMAPs, diSAmPAP, and their TPs occurred. The distribution patterns of the carbon chain lengths of the precursor PFAS in soil samples were shown to resemble those in paper samples. This supports the hypothesis that paper sludge is a major source of contamination. The presence of major degradation products like PFCAs, FTSAs, or PFOS and their distribution of carbon chain lengths indicate the activity of biotic or abiotic degradation processes and selective leaching processes from the upper soil horizons.Graphical abstract

Third phase formation behaviour of tris(2-methylbutyl) phosphate and tri-n-alkyl phosphates in the extraction of mineral acids and tetravalent metal ions

Abstract The formation of third phase is a detrimental phenomenon witnessed in the nuclear separation processes during the extraction of certain metal salts by an organic solution, which comprises of a neutral extractant, tri-n-butyl phosphate dispersed in a non-polar diluent, n-dodecane (n-C12H26). In the present work, a comparative analysis on the third phase formation behaviour of three trialkyl phosphates, TBP, its linear and branched higher homologues tri-n-amyl phosphate and tris(2-methylbutyl) phosphate (T2MBP), respectively, have been provided which will be useful for the identification of an extractant with minimum third phase formation tendency. The organic phase splitting behaviour during the extraction of three mineral acids (HClO4, HCl and HNO3) and two tetravalent metal nitrates (Th(IV) and Zr(IV)) by trialkyl phosphates has been investigated to understand the influence of anionic and cationic components, respectively, in third phase formation of trialkyl phosphates. The effect of structure of the alkyl groups of trialkyl phosphate and chain length of diluents on third phase formation during Zr(IV) extraction from HNO3 media have also been studied. Overall, the third phase formation behaviour of T2MBP was found to be lower both for the extraction of mineral acid and Zr(IV), thereby indicating its potentiality for applications in various solvent extraction processes.

Gestational Exposure to Organophosphate Pesticides and Longitudinally Assessed Behaviors Related to Attention-Deficit/Hyperactivity Disorder and Executive Function.

The brain’s prefrontal cortex directs higher-order cognitive and behavioral processes that are important for attention, working memory, and inhibitory control. We investigated whether gestational exposure to organophosphate (OP) pesticides was associated with these abilities in childhood and early adolescence. Between 1999 and 2000, we enrolled pregnant women in a birth cohort drawn from an agricultural region of California. We measured dialkyl phosphate (DAP) metabolites of OP pesticides in maternal pregnancy urine samples (13 and 26 weeks) and estimated associations with behaviors related to attention-deficit/hyperactivity disorder and executive function, assessed longitudinally; 351 families provided neurodevelopmental outcome data at any point when the child was aged 7–12 years. We assessed function across multiple dimensions (e.g., working memory, attention), methods (e.g., behavior reports, child assessment), and reporters (e.g., mothers, teachers, child self-reports). Higher gestational DAP concentrations were consistently associated with behaviors related to attention-deficit/hyperactivity disorder and executive function. For example, a 10-fold increase in gestational DAP concentration was associated with poorer longitudinally assessed Behavior Rating Inventory of Executive Function scores, as reported by mothers (β = 4.0 (95% confidence interval: 2.1, 5.8); a higher score indicates more problems), and Weschler Intelligence Scale for Children—Fourth Edition Working Memory scores (a 3.8-point reduction; β = −3.8 (95% confidence interval: −6.2, −1.3)). Reducing gestational exposure to OP pesticides through public health policy is an important goal.