Pinacolyl Methylphosphonate Research Articles

The high potential of the pure and Nb-doped δ-FeOOH (001) surface in the adsorption and degradation of a neurotoxic agent

The adsorption and degradation of the Soman molecule (Pinacolyl methylphosphonofluoridate, C7H16FO2P) was investigated using the pure and Nb-doped δ-FeOOH (001) surfaces with density functional theory (DFT) calculations. We verified the Soman molecule adsorb on pure and doped surface through interaction preferably via interaction between phosphoryl oxygen (P = O) and hydroxyl groups from surface. The degradation of the Soman molecule on the δ-FeOOH and Nb-δ-FeOOH (001) surfaces was evaluated by the study of the reaction path, were found one transition state for both surfaces, corresponding to a maximum stretch of F-P = O group from Soman molecule and the bond breaking of hydroxyl group bonded to Fe/Nb. The activation energies found are 16.58 and 8.80 kcal/mol to pure and doped surface, respectively. The obtained products consisted of a negatively charged pinacolyl methylphosphonate molecule and HF molecule adsorbed on the positively charged surface. Both δ-FeOOH and Nb-δ-FeOOH (001) surfaces show great potential to adsorb and degrade the Soman neurotoxic agent, however the presence of Nb further favors the process.

Toxic effects and bioaccumulation of pinacolyl methylphosphonate acid in zebrafish following soman exposure to a water environment.

Soman has been shown to be highly neurotoxic and can be easily degraded to produce pinacolyl methylphosphonate acid (PMPA). Thus, the perniciousness of PMPA deserved serious attention after soman was exposed to the environment. However, the toxicity of PMPA was not clearly elucidated to date. In this regard, the objective of this study was to determine if PMPA could pose an environmental risk after soman exposure to a water environment. In this study, the toxicity and bioaccumulation assessments of PMPA were carried out on zebrafish. Histological examination was used to assess the toxicity of PMPA in zebrafish and revealed that PMPA has chronic toxicity in view of tissue injury. The contents of PMPA in whole zebrafish and tissues were determined after soman exposure. The result showed that PMPA bioaccumulated in the whole zebrafish and tissue, especially the liver and intestinal tissues. This is the first report showing that the hydrolyzate of a G-series chemical nerve agent could accumulate in organisms. This study offers novel insights into the environmental risk assessments associated with soman exposure to a water environment.

Source Attribution of the Chemical Warfare Agent Soman Using Position-Specific Isotope Analysis by 2H NMR Spectroscopy: From Precursor to Degradation Product.

Position-specific isotope analysis (PSIA) by NMR spectroscopy is a technique that provides quantitative isotopic values for every site—a so-called isotopic fingerprint—of a compound of interest. The isotopic fingerprint can be used to link samples with a common origin or to attribute a synthetic chemical to its precursor source. Despite PSIA by NMR being a powerful tool in chemical forensics, it has not yet been applied on chemical warfare agents (CWAs). In this study, different batches of the CWA Soman were synthesized from three distinctive pinacolyl alcohols (PinOHs). Prior to NMR analysis, the Soman samples were hydrolyzed to the less toxic pinacolyl methylphosphonate (PMP), which is a common degradation product. The PinOHs and PMPs were applied to PSIA by 2H NMR experiments to measure the isotopic distribution of naturally abundant 2H within the pinacolyl moiety. By normalizing the 2H NMR peak areas, we show that the different PinOHs have unique intramolecular isotopic distributions. This normalization method makes the study independent of references and sample concentration. We also demonstrate, for the first time, that the isotopic fingerprint retrieved from PSIA by NMR remains stable during the production and degradation of the CWA. By comparing the intramolecular isotopic profiles of the precursor PinOH with the degradation product PMP, it is possible to attribute them to each other.

Adsorptive Removal of Nerve Agent Gases by Carbon Nanotubes: A Density Functional Theory Study

Abstract Density functional theory (DFT) studies were performed to evaluate the adsorption behavior and electronic response of (4,4) carbon nanotubes (CNTs) to the organophosphorus nerve agents 3,3-dimethylbutan-2-yl methyl phosphono fluoridate (Soman), pinacolyl methyl phosphonate (SOS), diethyl fluorophosphates (SAS-F) and diethyl chlorophosphate (SAS-Cl). The calculations were performed using the triple numerical plus polarization (TNP) as the basis set with an orbital cutoff of 4.5 Å. The electronic exchange and correlation effects were analyzed by generalized gradient approximation (GGA) with the BLYP parameterization. The studied systems were fully optimized and adsorption energy (E ad), interaction distances, geometric and electronic structures were investigated. According to the obtained relatively high E ad, it was shown that Soman, SOS, SAS-Cl and SAS-F more likely to be absorbed on the CNTs surfaces, introducing an interesting candidate for chemisorption of the nerve agent gas molecules. As a result, the order of increasing of the E ad values of the studied systems were |E ad SAS-F/CNT| > |E ad SAS-Cl/CNT| > |E ad SOS/CNT| > |E ad Soman/CNT| systems. The calculated partial density of states (PDOS) of the adsorption systems confirmed the strong electrons interaction between the nerve agent molecules and the CNTs surfaces. The obtained results indicated the potential application of CNTs in the design and fabrication of protective low-cost gas filters against toxic odorless nerve agent gases.

Computational evaluation of the chemical warfare agents capture performances of robust MOFs

Abstract A series of stable MOFs containing zirconium or titanium ions as metal centers was screened to assess their capture performances for nerve agents including sarin and soman as well as their standard simulants, i.e. the dimethyl-methyl-phosphonate and diisopropyl fluorophosphate. These Monte Carlo simulations revealed that some of these MOFs show very high uptakes that significantly outperform those of other families of porous materials and interestingly they exhibit a very high affinity for these toxic molecules at low loading. These combined features make them potentially attractive to act as nerve agent filters. This set of adsorption data was further rationalized to establish structure-adsorption performances relationship and Monte Carlo simulations were combined with Density Functional Theory calculations to gain more insight into the adsorption mechanism in play. Finally, the choice of reliable simulants to accurately mimic the adsorption behavior of real toxic molecules in MOFs has been further discussed and in particular it has been established that soman is better described considering the pinacolyl methylphosphonate rather than the standard dimethyl-methyl-phosphonate and diisopropyl fluorophosphate simulants.

Ambient vapor sampling and selective cluster formation for the trace detection of tributyl phosphate via atmospheric flow tube mass spectrometry

In addition to serving as an f-element ligand and rare-earth method complexing agent, tributyl phosphate is a compound containing core functional groups that mimic those routinely found in degradation products from industrial processes. Because detection of trace quantities of tributyl phosphate can provide insight into the routes of contamination and degradation in the environment, there is a need to develop methods capable of detecting trace quantities of tributyl phosphate. Vapor detection at atmospheric pressure is one approach that is both sensitive and rapid. We present here the use of atmospheric flow tube mass spectrometry for the ambient vapor sampling of tributyl phosphate from headspace of ppb-level solutions in methanol. Gas phase clustering reactions were to enhance detection levels via the addition of small quantities of the dopants diethylamine, triethylamine, and pinacolyl methylphosphonate in the vapor stream. Detection of the tributyl phosphate vapor emanating from these solutions demonstrated a linear range for the protonated tributyl phosphate species of 1–1000 ppb from solution. The clusters of tributyl phosphate with diethylamine, triethylamine, and pinacolyl phosphonate each yielded linear ranges of 1–250 ppb for tributyl phosphate in solution. Despite smaller linear ranges, the addition of these dopant species added a layer of analytical selectivity and reduced variability in signals from quality control samples. These data were obtained using an atmospheric flow tube source coupled to a linear ion trap mass spectrometer, which demonstrates the applicability of trapping systems to the atmospheric flow tube ionization technique while monitoring positive ions.

NMR chemical shift and J coupling parameterization and quantum mechanical reference spectrum simulation for selected nerve agent degradation products in aqueous conditions.

The spectral parameters of selected nerve agent degradation products relevant to the Chemical Weapons Convention, namely, ethyl methylphosphonate, isopropyl methylphosphonate, pinacolyl methylphosphonate and methylphosphonic acid, were studied in wide range of pH conditions and selected temperatures. The pH and temperature dependence of chemical shifts and J couplings was parameterized using Henderson-Hasselbalch-based functions. The obtained parameters allowed calculation of precise chemical shifts and J coupling constants in arbitrary pH conditions and typical measurement temperatures, thus facilitating quantum mechanical simulation of reference spectra in the chosen magnetic field strength for chemical verification. Copyright © 2017 John Wiley & Sons, Ltd.

Effective methylation of phosphonic acids related to chemical warfare agents mediated by trimethyloxonium tetrafluoroborate for their qualitative detection and identification by gas chromatography-mass spectrometry

The effective methylation of phosphonic acids related to chemical warfare agents (CWAs) employing trimethyloxonium tetrafluoroborate (TMO·BF4) for their qualitative detection and identification by gas chromatography-mass spectrometry (GC-MS) is presented. The methylation occurs in rapid fashion (1 h) and can be conveniently carried out at ambient temperature, thus providing a safer alternative to the universally employed diazomethane-based methylation protocols. Optimization of the methylation parameters led us to conclude that methylene chloride was the ideal solvent to carry out the derivatization, and that even though methylated products can be observed surfacing after only 1 h, additional time was not found to be detrimental but beneficial to the process particularly when dealing with analytes at low concentrations (∼10 μg mL−1). Due to its insolubility in methylene chloride, TMO·BF4 conveniently settles to the bottom during the reaction and does not produce additional interfering by-products that may further complicate the GC-MS analysis. The method was demonstrated to successfully methylate a variety of Schedule 2 phosphonic acids, including their half esters, resulting in derivatives that were readily detected and identified using the instrument's spectral library. Most importantly, the method was shown to simultaneously methylate a mixture of the organophosphorus-based nerve agent hydrolysis products: pinacolyl methylphosphonate (PMPA), cyclohexyl methylphosphonate (CyMPA) and ethyl methylphosphonate (EMPA) (at a 10 μg mL−1 concentration each) in a fatty acid ester-rich organic matrix (OPCW-PT-O3) featured in the 38th Organisation for the Prohibition of Chemical Weapons (OPCW) Proficiency Test. In addition, the protocol was found to effectively methylate N,N-diethylamino ethanesulfonic acid and N,N-diisopropylamino ethanesulfonic acid that are products arising from the oxidative degradation of the V-series agents VR and VX respectively. The work described herein represents the first report on the use of TMO·BF4 as a viable, stable and safe agent for the methylation of phosphonic acids and their half esters and within the context of an OPCW Proficiency Test sample analysis.

Concise and Efficient Fluorescent Probe via an Intromolecular Charge Transfer for the Chemical Warfare Agent Mimic Diethylchlorophosphate Vapor Detection.

Sarin, used as chemical warfare agents (CWAs) for terrorist attacks, can induce a number of virulent effects. Therefore, countermeasures which could realize robust and convenient detection of sarin are in exigent need. A concise charge-transfer colorimetric and fluorescent probe (4-(6-(tert-butyl)pyridine-2-yl)-N,N-diphenylaniline, TBPY-TPA) that could be capable of real-time and on-site monitoring of DCP vapor was reported in this contribution. Upon contact with DCP, the emission band red-shifted from 410 to 522 nm upon exposure to DCP vapor. And the quenching rate of TBPY-TPA reached up to 98% within 25 s. Chemical substances such as acetic acid (HAc), dimethyl methylphosphonate (DMMP), pinacolyl methylphosphonate (PAMP), and triethyl phosphate (TEP) do not interfere with the detection. A detection limit for DCP down to 2.6 ppb level is remarkably achieved which is below the Immediately Dangerous to Life or Health concentration. NMR data suggested that a transformation of the pyridine group into pyridinium salt via a cascade reaction is responsible for the sensing process which induced the dramatic fluorescent red shift. All of these data suggest TBPY-TPA is a promising fluorescent sensor for a rapid, simple, and low-cost method for DCP detection, which could be easy to prepare as a portable chemosensor kit for its practical application in real-time and on-site monitoring.

PREPARASI CONTOH UJI PROFISIENSI UNTUK IDENTIFIKASI SENYAWA KIMIA BERBAHAYA

The sample of proficiency test for hazard chemical compounds in organic and water sample has been made to identify hazard chemical compounds. Here, various matrix was added to these hazard chemical compound. The organic sample derived from organic waste added with dichloromethane as the solvent, undecane 100 µl/mL, 1,2-dimethylbenzene 12 µl/mL, diesel 100 µl/mL and tributhyl phosphate 10,02 µg/mL, whereas water sample derived from water waste added with magnesium sulfate heptahydrate 120 µg/mL, sodium carbonate anhydrous 106 µg/mL, sodium sulfate anhydrous 284 µg/mL, calsium chloride dyhidrate 222 µg/mL, dikhloromethane 2,5 µl/mL, polyethylene glycol 505,4 µg/mL, 3,5 dihydroxytoluene 10,05 µg/mL and α methyl-α-propyl succinimide 10,01 µg/mL. Hazard chemical compounds that being added are Bis (3-methylbutyl) ethylphosphonate 10,04±0,31 µg/mL, Bis (2-chloroethyl) methylamine 20,59±0,14 µg/mL for organic sample and Pinacolyl methylphosphonate 9,80±0,18 µg/mL and Triethanolamine 14,84±0,10 µg/mL for water sample. Homogeneity and stability are determined quantitatively using GC-FPD (P-mode) and GC-FID with calibration curve using internal standard dibuty butylphosphonate, 2,6-dimethylphenol, dibutylphosphate and Bis (2-hydroxypropyl) aminoethanol with Relative Standard Deviation (RSD) 8,10 % and 12,40 µg/mL for Bis (3-methylbutyl) ethylphosphonate and 3,46 % and 14,19 µg/mL for Bis (2-chloroethyl) methylamine and 2,22 % and 11,28 µg/mL for Pinacolyl methylphosphonate and 2,70 % and 11,47 µg/mL for Triethanolamine. Relative Standard Deviation is a homogeneity value with requirements below 20 % and stability is a degradation result which value is less than 30 %.Keywords: hazard chemical compounds, proficiency test, homogeneity, stability, relative standard deviation

Investigation of the Persistence of Nerve Agent Degradation Analytes on Surfaces through Wipe Sampling and Detection with Ultrahigh Performance Liquid Chromatography-Tandem Mass Spectrometry

The persistence of chemical warfare nerve agent degradation analytes on surfaces is important, from indicating the presence of nerve agent on a surface to guiding environmental restoration of a site after a release. Persistence was investigated for several chemical warfare nerve agent degradation analytes on indoor surfaces and presents an approach for wipe sampling of surfaces, followed by wipe extraction and liquid chromatography-tandem mass spectrometry detection. Commercially available wipe materials were investigated to determine optimal wipe recoveries. Tested surfaces included porous/permeable (vinyl tile, painted drywall, and wood) and largely nonporous/impermeable (laminate, galvanized steel, and glass) surfaces. Wipe extracts were analyzed by ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). UPLC provides a separation of targeted degradation analytes in addition to being nearly four times faster than high-performance liquid chromatography, allowing for greater throughput after a large-scale contamination incident and subsequent remediation events. Percent recoveries from nonporous/impermeable surfaces were 60-103% for isopropyl methylphosphonate (IMPA), GB degradate; 61-91% for ethyl methylphosphonate (EMPA), VX degradate; and 60-98% for pinacolyl methylphosphonate (PMPA), GD degradate. Recovery efficiencies for methyl phosphonate (MPA), nerve agent degradate, and ethylhydrogen dimethylphosphonate (EHDMAP), GA degradate, were lower, perhaps due to matrix effects. Diisopropyl methylphosphonate, GB impurity, was not recovered from surfaces. The resulting detection limits for wipe extracts were 0.065 ng/cm(2) for IMPA, 0.079 ng/cm(2) for MPA, 0.040 ng/cm(2) for EMPA, 0.078 ng/cm(2) for EHDMAP, and 0.013 ng/cm(2) for PMPA. The data indicate that laboratories may hold wipe samples for up to 30 days prior to analysis. Target analytes were observed to persist on surfaces for at least 6 weeks.

Real-time detection of chemical warfare agent simulants in forensic samples using active capillary plasma ionization with benchtop and field-deployable mass spectrometers

A novel analytical technique to detect chemical warfare agent (CWA) simulants in forensic samples is presented. Three G-agent type simulants that closely mimic real CWAs, namely dimethyl methylphosphonate (DMMP), diethyl ethylphosphonate (DEEP), and diethyl phosphoramidate (DEPA), and in addition a hydrolysis product, pinacolyl methylphosphonate (PMP), were utilized. Dilute solutions spotted onto six different forensic matrices were used to evaluate the capability of an active capillary plasma ionization source, which could be attached to the inlets of either a conventional benchtop ion trap mass spectrometer or a miniaturized ion trap mass spectrometer, under ambient conditions. The sample solutions and matrix surfaces were exposed for about 10–20 seconds at a distance of 1 cm from the plasma ion source inlet. This real-time methodology was found to have a shorter analysis time than previously reported techniques. A full method validation, quantitative studies, and optimization for detection of real CWAs on forensic matrices should be done in the future.

Polyclonal Antibody to Soman-Tyrosine

Soman forms a stable, covalent bond with tyrosine 411 of human albumin, with tyrosines 257 and 593 in human transferrin, and with tyrosine in many other proteins. The pinacolyl group of soman is retained, suggesting that pinacolyl methylphosphonate bound to tyrosine could generate specific antibodies. Tyrosine in the pentapeptide RYGRK was covalently modified with soman simply by adding soman to the peptide. The phosphonylated-peptide was linked to keyhole limpet hemocyanin, and the conjugate was injected into rabbits. The polyclonal antiserum recognized soman-labeled human albumin, soman-mouse albumin, and soman human transferrin but not nonphosphonylated control proteins. The soman-labeled tyrosines in these proteins are surrounded by different amino acid sequences, suggesting that the polyclonal recognizes soman-tyrosine independent of the amino acid sequence. Antiserum obtained after 4 antigen injections over a period of 18 weeks was tested in a competition ELISA where it had an IC50 of 10(-11) M. The limit of detection on Western blots was 0.01 μg (15 picomoles) of soman-labeled albumin. In conclusion, a high-affinity, polyclonal antibody that specifically recognizes soman adducts on tyrosine in a variety of proteins has been produced. Such an antibody could be useful for identifying secondary targets of soman toxicity.

Development of Cotton Nonwoven Composite Fabric for Toxic Chemical Decontamination and Characterization of its Adsorption Capabilities

Because of the current threat of toxic chemicals and chemical warfare agents, personal protection is important for soldiers and first responders, as well as the civilian population. This paper describes the development of a cotton non-particulate nonwoven composite fabric and the evaluation of its adsorption capability for protection against toxic chemical ingress which can be harmful or lethal. In addition, this paper focuses on the evaluation of toxic chemical adsorption capabilities of various chemical protective substrates that have the potential to be used in military applications. The development of a three-layered cotton based decontamination wipe and its adsorption of 0.1 % w/v pinacolyl methylphosphonate in butanol, is presented. Adsorption is quantified using a modified gravimetric procedure developed using a thermogravimetric analyzer. The results demonstrate the adsorption performance of a new cotton-based, non-particulate flexible composite that has a high potential to be used as a portable decontamination wipe. This research is unique in the area of individual protection and addresses the requirements of the U.S. Department of Defense (DoD) for seeking and evaluating highly efficient, non-particulate, and skin-friendly materials that provide necessary chemical protection while minimizing any discomfort or irritation.

Simultaneous detection of CMPA and PMPA, hydrolytes of soman and cyclosarin nerve agents, by nanopore analysis

A sensitive nanopore-based analytical method was developed for the detection of cyclohexyl methylphosphonic acid (CMPA) and pinacolyl methylphosphonate (PMPA), hydrolytes of nerve agents soman and cyclosarin, respectively. The method uses a multi-functionalized α-hemolysin protein ion channel as the sensing element, with a host molecule β-cyclodextrin lodged in the lumen of the channel as a molecular adapter. The capture and release of CMPA/PMPA by the β-cyclodextrin host caused current modulations in the nanopore. Since the event residence times and amplitudes were significantly different, CMPA and PMPA could conveniently be differentiated and simultaneously quantitated.

Oxidative degradation of chemical warfare agents in water by bleaching powder

Degradation of sulfur mustard (HD), S-2-(di-isopropylamino)ethyl O-ethyl methylphosphonothioate (VX) and Soman (GD) in water by bleaching powder was investigated. The degradation products were comprehensively analyzed by gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS) and ion chromatography. Degradation pathways were deduced based on the identified products. The product analysis results indicated that HD could be degraded through oxidation and chlorination reactions, and a small portion of sulfur atoms could be mineralized into SO(4)(2-) ion. Oxidative degradation of VX could finally generate O-ethyl methylphosphonate acid (EMPA), sulfonic acids, SO(4)(2-) and NO(3)(-) ions. GD would be converted into non-toxic pinacolyl methylphosphonate via nucleophilic substitution.

Zirconia coated stir bar sorptive extraction combined with large volume sample stacking capillary electrophoresis-indirect ultraviolet detection for the determination of chemical warfare agent degradation products in water samples

In this study, a sensitive, selective and reliable analytical method by combining zirconia (ZrO2) coated stir bar sorptive extraction (SBSE) with large volume sample stacking capillary electrophoresis-indirect ultraviolet (LVSS-CE/indirect UV) was developed for the direct analysis of chemical warfare agent degradation products of alkyl alkylphosphonic acids (AAPAs) (including ethyl methylphosphonic acid (EMPA) and pinacolyl methylphosphonate (PMPA)) and methylphosphonic acid (MPA) in environmental waters. ZrO2 coated stir bar was prepared by adhering nanometer-sized ZrO2 particles onto the surface of stir bar with commercial PDMS sol as adhesion agent. Due to the high affinity of ZrO2 to the electronegative phosphonate group, ZrO2 coated stir bars could selectively extract the strongly polar AAPAs and MPA. After systematically optimizing the extraction conditions of ZrO2-SBSE, the analytical performance of ZrO2-SBSE-CE/indirect UV and ZrO2-SBSE-LVSS-CE/indirect UV was assessed. The limits of detection (LODs, at a signal-to-noise ratio of 3) obtained by ZrO2-SBSE-CE/indirect UV were 13.4–15.9μg/L for PMPA, EMPA and MPA. The relative standard deviations (RSDs, n=7, c=200μg/L) of the corrected peak area for the target analytes were in the range of 6.4–8.8%. Enhancement factors (EFs) in terms of LODs were found to be from 112- to 145-fold. By combining ZrO2 coating SBSE with LVSS as a dual preconcentration strategy, the EFs were magnified up to 1583-fold, and the LODs of ZrO2-SBSE-LVSS-CE/indirect UV were 1.4, 1.2 and 3.1μg/L for PMPA, EMPA, and MPA, respectively. The RSDs (n=7, c=20μg/L) were found to be in the range of 9.0–11.8%. The developed ZrO2-SBSE-LVSS-CE/indirect UV method has been successfully applied to the analysis of PMPA, EMPA, and MPA in different environmental water samples, and the recoveries for the spiked water samples were found to be in the range of 93.8–105.3%.

QCM sensing of a chemical nerve agent analog via electropolymerized molecularly imprinted polythiophene films

AbstractThe highly selective and sensitive detection of a chemical nerve agent analog pinacolyl methylphosphonate (PMP) was demonstrated using an electrochemically molecularly imprinted polymer (MIP) polythiophene film onto a quartz crystal microbalance (QCM) transducer surface. The fabrication and optimization of the sensor film was monitored by in situ electrochemistry‐QCM (EC‐QCM) measurements, which determined the change in mass and simultaneous change in redox properties of the polymer film. The film deposition, template loading, and template removal were evidenced by a combination of surface characterization techniques such as the attenuated total reflection infrared spectroscopy and high‐resolution X‐ray photoelectron spectroscopy. The fabricated MIP film demonstrated a limit of detection and a limit of quantification of ∼60 and ∼197 μM, respectively. The linear sensing range is between 125 and 250 μM concentration of PMP. Finally, theoretical modeling (AM1 semiempirical quantum calculations) studies revealed that a stable prepolymerization complex is formed in solution with the existence of H‐bonding interactions using the 2:1 monomer‐to‐template ratio. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Imprinted Polymer Inclusion Membrane Based Potentiometric Sensor for Determination and Quantification of Diethyl Chlorophosphate in Natural Waters

Biomimetic potentiometric sensor for the determination of diethyl chlorophosphate was developed using im- printed polymer inclusion membrane strategy. Semi-covalent imprinted and non-imprinted polymer particles were synthesized and found that non-imprinted polymer inclusion membrane was unstable in contrast to im- printed polymer inclusion membrane in determination and quantification of diethyl chlorophosphate. Im- printed polymer inclusion membrane based sensor found to be pH dependant with a 5 min equilibrium response time at pH = 10.5 and linearly responds to diethyl chlorophosphate in the concentration range of 1 × 10–9 to 1 × 10–4 and 1 × 10–4 to 1 × 10–1 mol●L–9 with a detection limit of 1 × 10–9 mol●L–1 (0.17 ppb). It was found that diethyl chlorophosphate response was selective against various selected interferents like pinacolyl methylphosphonate, dimethyl methyl phosphonate, methylphosphonic acid, Phorate and 2, 4-D. The devel- oped sensor was found to be stable for 3 months and can be reusable more than 30 times without loosing sensitivity. The developed sensor was successfully applied for the determination of diethyl chlorophosphate in natural waters.

Novel Stoichiometric, Noncovalent Pinacolyl Methylphosphonate Imprinted Polymers: A Rational Design by NMR Spectroscopy

The stoichiometric noncovalent imprinting of pinacolyl methylphosphonate (PMP), a degradation product of a chemical warfare agent, has been investigated. A rational approach consisting of controlling the number of specific sites produced during the polymerization was carried out in order to design the methacrylic acid (MAA)-based imprinted polymers. The objective of the method was to study by NMR spectroscopy the molecular association process between the monomer (MAA) and the template (PMP) in solution. Accurate variations in the chemical shifts of 1H and 13C were determined in a series of samples at various concentrations in the mixture of acetonitrile/toluene (3:1, v/v). By using an elaborated data treatment, we were able to simultaneously determine the stoichiometry, the association constant, and the condensation degree of the resulting complex. On the basis of these results, a stoichiometric noncovalent PMP-imprinted polymer was subsequently synthesized. Adsorption isotherms of the materials were meas...