Chemical Warfare Agent Degradation Products Research Articles

Mass Spectrometric Identification of Chemical Warfare Agent Adducts with Biological Macromolecule for Verification of Their Exposure

Exposure to chemical warfare agents (CWAs) can be verified by detecting their degradation products in biological samples. However, the half-lives of these CWA degradation products in the body are short. CWAs are known to combine with biological macromolecules and the covalently bound compounds are called adducts. The residence time of adducts in the human body is longer than that of the corresponding CWA degradation products. Therefore, development of analytical methods to detect these adducts is a more realistic way of verifying CWA exposure. In this mini review, we describe the present state of research on analytical methods for identifying CWA adducts, and mainly introduce our research on nerve gas adducts using a direct method. Novel analytical methods for verifying low level exposure to nerve gases use liquid chromatography-mass spectrometry (LC-MS). Butyrylcholinesterase (BuChE) has been purified by affinity chromatography and sodium dodecylsulfate poly-acrylamide gel electrophoresis. The purified enzyme is inhibited by nerve gases (sarin, VX and soman) and digested by chymotrypsin, and then the peptides are analyzed by LC-MS and LC tandem MS. The peptide fragment that is combined with nerve gas is detected by LC-MS. Furthermore, the chemical structure of the adduct peptide characterized by MS provides structural information about the analyte. The detection limit of BuChE or BuChE adduct is estimated at 4 ng/injection (53 fmol/injection). If at least 1% of BuChE activity is inhibited by nerve gas, the adduct can be detected at a level of 1% BuChE inhibition in the victim's serum.

Detection of chemical warfare agent degradation products in foods using liquid chromatography coupled to inductively coupled plasma mass spectrometry and electrospray ionization mass spectrometry

The following work presents the exploration of three chromatographic separations in combination with inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of chemical warfare agent degradation products (CWADPs). The robust ionization of ICP is virtually matrix independent thus enabling the examination of sample matrices generally considered too complicated for analysis by electrospray ionization (ESI) or atmospheric pressure chemical ionization MS with little to no sample preparation. The analysis was focused on detecting CWADPs in food matrices, as they present possible vehicles for terrorist contamination. Due to the specific detection of 31P by ICP-MS, resolution of analytes of interest from other P-containing interferences (H 3PO 4) was a crucial part of each separation. Up to 10 CWADPs were separated in the presence of H 3PO 4 with detection limits in the low part per billion levels using the methods described. Additionally, one method was tailored to be compatible with both ICP-MS and ESI-MS making structural verification possible.

Poly(dimethylsiloxane) Microchip Electrophoresis with Contactless Conductivity Detection for Measurement of Chemical Warfare Agent Degradation Products

The applicability of a poly(dimethylsiloxane) (PDMS) microfluidic device with contactless conductivity detection for the determination of organophosphonate nerve agent degradation products is reported. Five alkyl methylphosphonic acids, isopropyl methylphosphonic acid (IMPA), pinacolyl methylphosphonic acid (PMPA), O‐ethyl‐N,N‐dimethyl phosphoramidate (EDPA), ethyl methylphosphonic acid (EMPA), and methylphosphonic acid (MPA), (degradation products of Sarin, Soman, Tuban and VX nerve agents) were analyzed by microchip capillary electrophoresis. Experimental conditions for the separation and detection processes have been optimized to yield well‐defined separation and high sensitivity. Under optimal conditions, analyses were completed in less than 2 min. Linear relations between concentration and peak heights were obtained with detection limits in the 1.3–4.5 mg/l range and precision values for the peak heights were in the range of 3.4–6.1% RSD. Applicability of this method for natural (lake and tap) water samples was also demonstrated. Compared to conventional analytical methods, this miniaturized system offers promise for on‐site monitoring of degradation products of chemical warfare agents, with advantages of cost effective construction, simple operation, portability, and minimum sample consumption.

Field-amplified sample stacking for the detection of chemical warfare agent degradation products in low-conductivity matrices by capillary electrophoresis-mass spectrometry

Preconcentration of chemical warfare agent degradation products (alkylphosphonic acids and alkyl alkylphosphonic acids) in low-conductivity matrices (purified water, tap water and local river water) by field-amplified sample stacking (FASS) was developed for capillary electrophoresis (CE) coupled to ion trap mass spectrometry. FASS was performed by adding a mixture of HCOONH 4 and NH 4OH in appropriate concentrations to the sample. This allowed to control the conductivity and the pH of the sample in order to obtain FASS performances that are independent of analyte concentration. The influence of different parameters on FASS (sample to background electrolyte (BGE) conductivity ratio, injection volume and concentration of BGE) was studied to determine the optimal conditions and was rationalized by using the theoretical model developed by Burgi and Chien. A good correlation was obtained between the bulk electroosmotic velocity predicted by this model and the experimental value deduced from the migration time of the electroosmotic flow marker detected by mass spectrometry (MS). This newly developed method was successfully applied to the analysis of tap water and local river water fortified with the analytes and provided a 10-fold sensitivity enhancement in comparison to the signal obtained without preconcentration procedure. The quite satisfactory repeatability and linearity for peak areas obtained in the 0.5–5 μg mL −1 concentration range allow quantitative analysis to be implemented. Limits of detection of 0.25–0.5 μg mL −1 for the alkyl alkylphosphonic acids and of 0.35–5 μg mL −1 for the alkylphosphonic acids were reached in tap water and river water.

Determination of Trace Amounts of Chemical Warfare Agent Degradation Products in Decontamination Solutions with NMR Spectroscopy

Decontamination solutions are used for an efficient detoxification of chemical warfare agents (CWAs). As these solutions can be composed of strong alkaline chemicals with hydrolyzing and oxidizing properties, the analysis of CWA degradation products in trace levels from these solutions imposes a challenge for any analytical technique. Here, we present results of application of nuclear magnetic resonance spectroscopy for analysis of trace amounts of CWA degradation products in several untreated decontamination solutions. Degradation products of the nerve agents sarin, soman, and VX were selectively monitored with substantially reduced interference of background signals by 1D 1H-31P heteronuclear single quantum coherence (HSQC) spectrometry. The detection limit of the chemicals was at the low part-per-million level (2-10 microg/mL) in all studied solutions. In addition, the concentration of the degradation products was obtained with sufficient confidence with external standards.

Derivatization of organophosphorus nerve agent degradation products for gas chromatography with ICPMS and TOF-MS detection

Separation and detection of seven V-type (venomous) and G-type (German) organophosphorus nerve agent degradation products by gas chromatography with inductively coupled plasma mass spectrometry (GC-ICPMS) is described. The nonvolatile alkyl phosphonic acid degradation products of interest included ethyl methylphosphonic acid (EMPA, VX acid), isopropyl methylphosphonic acid (IMPA, GB acid), ethyl hydrogen dimethylamidophosphate sodium salt (EDPA, GA acid), isobutyl hydrogen methylphosphonate (IBMPA, RVX acid), as well as pinacolyl methylphosphonic acid (PMPA), methylphosphonic acid (MPA), and cyclohexyl methylphosphonic acid (CMPA, GF acid). N-(tert-Butyldimethylsilyl)-N-methyltrifluroacetamide with 1% TBDMSCl was utilized to form the volatile TBDMS derivatives of the nerve agent degradation products for separation by GC. Exact mass confirmation of the formation of six of the TBDMS derivatives was obtained by GC-time of flight mass spectrometry (TOF-MS). The method developed here allowed for the separation and detection of all seven TBDMS derivatives as well as phosphate in less than ten minutes. Detection limits for the developed method were less than 5 pg with retention times and peak area precisions of less than 0.01 and 6%, respectively. This method was successfully applied to river water and soil matrices. To date this is the first work describing the analysis of chemical warfare agent (CWA) degradation products by GC-ICPMS.

Separation and identification of isomeric acidic degradation products of organophosphorus chemical warfare agents by capillary electrophoresis-ion trap mass spectrometry

Capillary electrophoresis (CE) coupled to ion trap mass spectrometry (MS) was evaluated for the separation and identification of chemical warfare agent degradation products (alkylphosphonic acids and alkyl alkylphosphonic acids). Different analytical parameters were optimized in negative ionization mode such as electrolyte composition (15 mM CH 3COONH 4, pH 8.8), sheath liquid composition (MeOH/H 2O/NH 3, 75:25:2, v/v/v), nebulization and ion trapping conditions. A standard mixture of five alkylphosphonic (di)acids and five alkyl alkylphosphonic (mono)acids containing isomeric compounds was used in order to evaluate CE selectivity and MS identification capability. The obtained electropherograms revealed that CE selectivity was very limited in the case of alkyl alkylphosphonic acid positional isomers, whereas isomeric isopropylphosphonic and propylphosphonic acids were baseline-separated. CE–MS–MS experiments provided an unambiguous identification of each isomeric co-migrating alkyl alkylphosphonic acids thanks to the presence of specific fragment ions. On the other hand, CE separation was mandatory for the identification of isomeric alkylphosphonic acids, which led to the same fragment ion and could not be differentiated by MS–MS. The developed method was applied to the analysis of soil extracts spiked with the analytes (before or after extraction treatment) and appeared to be very promising since resolution and sensitivity were similar to those observed in deionized water. Especially, analytes were detected and identified in soil extract spiked at 5 μg mL −1 with each compound before extraction treatment.

Ion-pair solid-phase extraction and gas chromatography–mass spectrometric determination of acidic hydrolysis products of chemical warfare agents from aqueous samples

The chemical warfare agents (CWA) degrade rapidly in aqueous samples and convert to acidic degradation products. Extraction and identification of the degradation products from complex matrices using simple sample preparation and sensitive detection and identification is the most important step in the off-site analysis of samples. In this present study, we report a simple sample preparation step based on ion-pair (IP) solid-phase extraction (SPE) for the extraction of acidic degradation products of CWA namely methyl, ethyl, propyl phosphonic acids, thiodiglycolic acid and benzilic acid. The analysis was performed on GC–MS in electron impact ionization mode. Three IP reagents triethylamine (TEA), tetrabutylammonium bromide (TBAB) and cetyltrimethyl ammonium bromide (CTAB) were used. The recoveries were estimated using the internal and external standard methods. The recovery of the compounds was almost negligible when TEA was used as IP reagent. The recoveries obtained when TBAB and CTAB were used as IP reagents were high and reproducible. The recovery of test chemicals is above 90%, except for methyl phosphonic acid and ethylphosphonic acid (20.6 ± 3.2% and 35.8 ± 2.5%, respectively). The minimum detection limits of the method were calculated for all chemicals in both full scan and selected ion monitoring modes. The test chemicals could be detected in microgram per litre quantities by the IP–SPE method.

An integrated ecotoxicological approach to assess the effects of pollutants released by unexploded chemical ordnance dumped in the southern Adriatic (Mediterranean Sea)

In order to gain preliminary knowledge about the threat to marine ecosystems due to leakage of chemical warfare agents (CWAs) and other pollutants from rusting bombshells on the seabed, a case study was conducted in a dumping area in the southern Adriatic Sea (depth 200–300 m). Following electroacoustic and magnetometric surveys of the CWA dumping area, an integrated ecotoxicological approach was used. This approach was based on analysis of CWA residues and their metabolites, including arsenic, in sediment and organisms, as well as multimarker methodology including the Health Assessment Index, histological lesion analysis and enzyme assays. Two sentinel species were selected, the blackbelly rosefish [Helicolenus dactylopterus (Delaroche, 1809)] and the European conger (Conger conger L., 1758). Sediment analysis revealed the presence of CWA degradation products, including 1-4-thioxane and 1-4-dithiane. Tissues of fish from the CWA dumping site showed higher levels of arsenic than those from the reference site. Neither CWAs nor their metabolites were detected in fish tissues. Arsenic levels recorded in blackbelly rosefish were well above those reported for other fish species from the southern Adriatic, much higher than the FDA limit for food (2.6 mg kg−1) and close to the LD50 calculated for mammals (20 mg kg−1 body weight). The presence of pollutants in the CWA dumping site was also confirmed by pathological lesions in both species and EROD activity, two to three times higher than in fish from the reference site (16.45±8.08 and 8.05±5.87 pmol min−1 mg protein−1 in blackbelly rosefish and 269±24.92 and 78.71 pmol min−1 mg protein−1 in European conger, respectively). Cholinesterase activity seemed unaffected in muscle of both species, whereas in brain they were one-third of those recorded in fish from the reference site (14.22±10.05 and 72.87 nmol min−1 mg protein−1, respectively). This suggests that acetylcholinesterase is sensitive to CWAs. In conclusion, the agreement of all the chemical and biological parameters investigated suggests that the integrated ecotoxicological approach used is appropriate to reveal the presence and biological effects of CWAs in the marine ecosystem.

Detection of Aqueous Phase Chemical Warfare Agent Degradation Products by Negative Mode Ion Mobility Time-of-Flight Mass Spectrometry [IM(tof)MS

The use of negative ion monitoring mode with an atmospheric pressure ion mobility orthogonal reflector time-of-flight mass spectrometer [IM(tof)MS] to detect chemical warfare agent (CWA) degradation products from aqueous phase samples has been determined. Aqueous phase sampling used a traditional electrospray ionization (ESI) source for sample introduction and ionization. Certified reference materials (CRM) of CWA degradation products for the detection of Schedule 1, 2, or 3 toxic chemicals or their precursors as defined by the chemical warfare convention (CWC) treaty verification were used in this study. A mixture of six G-series nerve related CWA degradation products (EMPA, IMPA, EHEP, IHEP, CHMPA, and PMPA) and their related collision induced dissociation (CID) fragment ions (MPA and EPA) were found in each case to be clearly resolved and detected using the IM(tof)MS instrument in negative ion monitoring mode. Corresponding ions, masses, drift times, K(o) values, and signal intensities for each of the CWA degradation products are reported.

Reversed phase ion-pairing HPLC-ICP-MS for analysis of organophosphorus chemical warfare agent degradation products

The separation and analysis of three organophosphorus chemical warfare degradation products is described. Ethyl methylphosphonic acid (EMPA, the major hydrolysis product of VX), isopropyl methylphosphonic acid (IMPA, the major hydrolysis product of Sarin (GB)), and methylphosphonic acid (MPA, the final hydrolysis product of both) were the analytes and were separated by reversed phase ion-pairing high-performance liquid chromatography (RP-IP-HPLC) with the use of myristyl trimethylammonium bromide as ion-pairing reagent and an ammonium acetate–acetic acid buffer system (pH 4.85). An Agilent 7500ce inductively coupled plasma mass spectrometer (ICP-MS) equipped with collision/reaction cell technology was coupled to the chromatographic system for detection of 31P and 47PO+. Historically, ICP-MS detection of phosphorus has been limited due to its high first ionization potential (10.5 eV) and the presence of severe nitrogen polyatomic interferences (such as 14N16O1H+ and 15N16O+) overlapping its only isotope at m/z = 31. Implementation of an octopole reaction cell with helium as the cell gas allowed for removal of the nitrogen polyatomic interferences and reduction of background signal. Detection limits for EMPA, IMPA, and MPA were found to be 263, 183 and 139 pg mL−1, respectively, with separation in less than 15 min. The developed method was successfully applied to the analysis of spiked environmental water and soil samples.

Surface detection of chemical warfare agent simulants and degradation products

Chemical warfare agent (CWA) simulants as well as their degradation and hydrolysis products were detected from surfaces using thermal desorption ion mobility spectrometry (TD-IMS). CWA simulant materials that closely mimic the chemical structures of real CWA G/V-type nerve and S-type vesicant simulants were used in this study. Reduced mobility constants ( K 0) in air were reported for 20 compounds studied. Spectra for sample materials as low as 1 ng deposited on a paper filter were produced for most of the compounds. Detection limits as low as 15 pg of sample material with a sensitivity of 3.2 × 10 2 ampere per gram (A g −1) were reported. TD-IMS, which is normally used for the detection of explosives and drugs of abuse, demonstrated the capability of separating and detecting mixtures of CWA simulants, degradation and hydrolysis products from surface samples. TD-IMS demonstrated clear advantages of speed, high throughput and versatility over chromatographic methods of analysis for detecting CWA simulants, degradation and hydrolysis products. Successful development of the technique may lead to a practical and simple sensor for CWA and related compounds that could be installed and used at sensitive locations around the USA and throughout the world.

Measurements of chemical warfare agent degradation products using an electrophoresis microchip with contactless conductivity detector.

This paper reports on a microfluidic device for the screening of organophosphonate nerve agent degradation products. The miniaturized system relies on an efficient chip-based separation of alkyl methylphosphonic acids (breakdown products of Sarin, Soman, and VX nerve agents) followed by their sensitive contactless conductivity detection. Experimental parameters relevant to the separation and detection processes have been optimized to yield high sensitivity (with 48-86 microg L(-1) detection limits), fast response (50 s for a three alkyl methylphosphonic acid mixture), high precision (RSD = 3.8-5.0%), and good linearity (over the 0.3-100 mg L(-1) range). Applicability to natural (river) water samples is demonstrated. The new microsystem offers promise for monitoring degradation products of chemical warfare agents, with advantages of speed/warning, efficiency, portability, sample size, and cost compared to conventional ion chromatography or capillary electrophoresis systems.

Determination of soman and VX degradation products by an aspiration ion mobility spectrometry

An aspiration type ion mobility spectrometry (IMS) has been used to determine chemical warfare agent (CWA) degradation products from liquid samples. This technique is based on ion mobility which depends on the molecular weight, charge and shape. With this method, it is possible to measure the mobility distribution of positive and negative ion clusters simultaneously in six different electrodes. Each measuring electrode determines a different portion of the ion mobility distribution formed within the cell’s radioactive source. The strongest responses for all CWA degradation products and 2-propanol were seen in the order of sixth, fifth and second channels. On the basis of projection calculation, the fingerprints for 2-propanol and soman (GD; pinacolyl methylphosphonofluoridate) and VX o-ethyl- S-[2(diisopropylamino)ethyl] methylphosphonothioate) degradation products can be separated from each other. The detection levels for ethyl methylphosphonate (EMPA), pinacolyl methylphosphonate (PMPA), and ethylphosphonic acid (EPA) were 37.2 (37.2 μg/ml), 54.1 (54.1 μg/ml) and 55.1 ppm (55.1 μg/ml), respectively. However, the separation efficiency between different CWA degradation products was quite poor. The projections of these compounds were between 0.9976 and 0.9989, and this means that these fingerprints were identical. Thus, it is only possible to get one profile for all these degradation products of soman and VX. The data provided show that IMS is suitable as a simple technique for screening of CWA degradation products.

High-sensitivity determination of the degradation products of chemical warfare agents by capillary electrophoresis–indirect UV absorbance detection

Capillary electrophoresis coupled with indirect UV absorbance detection was employed for the determination of the chemical warfare agent degradation products: methylphosphonic acid, ethyl methylphosphonate, isopropyl methylphosphonate, and pinacolyl methylphosphonate. Glutamic acid was used as a buffering agent at its isoelectric point (pH 3.22). In its zwitterionic form, glutamic acid does not act as a competing co-anion in the system, thus providing buffering capacity while maintaining high sensitivity. The indirect probe (phenylphosphonic acid) concentration was lowered to 1 m M from the 10 m M in previous literature studies, further enhancing sensitivity. Detection limits of 2 μ M were achieved with hydrodynamic injection and up to 100-fold lower using electrokinetic injection. The increased buffering capacity of this system over previous methods led to migration time reproducibility RSD values of 0.18 to 0.22%. This represents a 10-fold improvement in reproducibility over previous studies with comparable or improved sensitivity.

Indirect laser-induced fluorescence detection for capillary electrophoresis using a violet diode laser.

The violet (415 nm) diode laser is used for indirect laser-induced fluorescence detection in capillary electrophoretic separations of inorganic anions and chemical warfare agent degradation products. Inorganic anions were detected using 8-hydroxypyrene-1,3,6-trisulfonic acid as the indirect probe and achieved submicromolar (40-80 ppb) detection limits in a 2-min separation. The chemical warfare agent degradation products methylphosphonic acid, ethyl methylphosphonate, isopropyl methylphosphonate, and pinacolyl methylphosphonate were detected using the porphyrin tetrakis(4-sulfophenyl)porphine as the indirect probe and achieved detection limits of 0.1 microM (9 ppb), which are 1 order of magnitude better than that achieved using indirect UV detection. Baseline stability achieved with the violet diode laser was excellent, with dynamic reserve (DR) values of > 1000, which are 15 times better than that achieved using an unstabilized HeCd laser.

The sources, fate, and toxicity of chemical warfare agent degradation products.

We include in this review an assessment of the formation, environmental fate, and mammalian and ecotoxicity of CW agent degradation products relevant to environmental and occupational health. These parent CW agents include several vesicants: sulfur mustards [undistilled sulfur mustard (H), sulfur mustard (HD), and an HD/agent T mixture (HT)]; nitrogen mustards [ethylbis(2-chloroethyl)amine (HN1), methylbis(2-chloroethyl)amine (HN2), tris(2-chloroethyl)amine (HN3)], and Lewisite; four nerve agents (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX), tabun (GA), sarin (GB), and soman (GD)); and the blood agent cyanogen chloride. The degradation processes considered here include hydrolysis, microbial degradation, oxidation, and photolysis. We also briefly address decontamination but not combustion processes. Because CW agents are generally not considered very persistent, certain degradation products of significant persistence, even those that are not particularly toxic, may indicate previous CW agent presence or that degradation has occurred. Of those products for which there are data on both environmental fate and toxicity, only a few are both environmentally persistent and highly toxic. Major degradation products estimated to be of significant persistence (weeks to years) include thiodiglycol for HD; Lewisite oxide for Lewisite; and ethyl methyl phosphonic acid, methyl phosphonic acid, and possibly S-(2-diisopropylaminoethyl) methylphosphonothioic acid (EA 2192) for VX. Methyl phosphonic acid is also the ultimate hydrolysis product of both GB and GD. The GB product, isopropyl methylphosphonic acid, and a closely related contaminant of GB, diisopropyl methylphosphonate, are also persistent. Of all of these compounds, only Lewisite oxide and EA 2192 possess high mammalian toxicity. Unlike other CW agents, sulfur mustard agents (e.g., HD) are somewhat persistent; therefore, sites or conditions involving potential HD contamination should include an evaluation of both the agent and thiodiglycol.

Rapid screening procedures for the hydrolysis products of chemical warfare agents using positive and negative ion liquid chromatography–mass spectrometry with atmospheric pressure chemical ionisation

Qualitative screening procedures have been developed for the rapid detection and identification of the hydrolysis products of chemical warfare agents in aqueous samples and extracts, using liquid chromatography–mass spectrometry with positive and negative atmospheric pressure chemical ionisation (APCI). Previously reported screening procedures, which used positive APCI or electrospray ionisation (ESI), were modified by using LC conditions that allowed acquisition of positive and negative ion mass spectra. APCI was generally found to be more robust than ESI, probably due to variable adduct ion formation with ESI, depending on the condition of the sample and the system. Negative APCI provided selective detection of acidic analytes and allowed facile differentiation of alkyl alkylphosphonic acids from isomeric dialkyl alkylphosphonates. The combination of positive and negative APCI, using a C 18 column and water–methanol mobile phase modified with ammonium formate, provides a rapid screening procedure for chemical warfare agent degradation products, with limits of detectability in the range 10–100 ng/ml. In the case of proficiency test samples, where analyte concentrations are in the range 1–10 ppm, introduction of the sample by infusion may provide an even faster preliminary screening procedure.

Determination of chemical warfare agent degradation products at low-part-per-billion levels in aqueous samples and sub-part-per-million levels in soils using capillary electrophoresis.

A significant enhancement in the method detection limits is observed in the analysis of chemical warfare agent (CWA) degradation products in environmental samples by capillary electrophoresis (CE) using electrokinetic injection. The CE method uses indirect UV detection of the nonderivitized acidic analyte and a cationic surfactant, didodecyldimethylammonium hydroxide, for reversal of the electroosmotic flow. Analytes studied include the dibasic acid methylphosphonic acid (MPA) and its monoacid/monoalkyl esters, RMPA, where R = ethyl, isopropyl, and pinacolyl (2-(3,3-dimethylbutyl)). The CE method uses an attractive buffer system which is highly stable and inexpensive, and, in addition to reversing the electroosmotic flow, provides excellent separation efficiencies within a 3-min run. This CE method is also free from interference caused by carbonate, humic acids, and fluoride. Compared to pressure injection, electrokinetic injection with this CE buffer system provided substantially lower detection limits, up to 100-fold lower for samples in reagent water. However, to best realize the benefits of the electrokinetic injection enhancement for environmental samples, a prior cleanup of the sample using standard ion-exchange cartridges is necessary. This cleanup step uses sequential cartridges to remove sulfate (barium cartridge), chloride (silver cartridge), and cations (H+ cartridge). Using this approach, detection limits for these four acids were as low as 1-2 micrograms/L for water samples and 25-50 micrograms/L for aqueous leachates of soil samples (10 mL of leachate/1.5 g of soil). The utility of this method for separation of CWA degradation products by CE is discussed in terms of pressure injection versus electokinetic injection. The effects of voltage and time of injection on the separation were investigated. Results from three types of soils and four types of water (groundwater, artificial seawater, tap water, bay water) indicated that the method has potential for environmental monitoring. Quantitative CE analysis with electrokinetic injection enhancement of detection limits of these types of environmental samples requires the use of an appropriate internal standard approach. The data presented here indicate that an internal standard-based approach could be expected to give analysis results in the sub-part-per-million concentration range of 90-110% of the true value.

Quantitative analysis of chemical warfare agent degradation products in reaction masses using capillary electrophoresis.

Quantitative methods have been developed for the analysis of chemical warfare agent degradation products in reaction masses using capillary electrophoresis (CE). This is the first report of a systematic validation of a CE-based method for the analysis of chemical warfare agent degradation products in agent neutralization matrixes (reaction masses). After neutralization with monoethanolamine/water, the nerve agent GB (isopropyl methylphosphonofluoridate, Sarin) gives isopropyl methylphosphonic acid (IMPA) and O-isopropyl O'-(2-amino)ethyl methylphosphonate (GB-MEA adduct). The nerve agent GD (pinacolyl methylphosphonofluoridate, Soman), [pinacolyl = 2-(3,3-dimethyl)butyl] produces pinacolyl methylphosphonic acid (PMPA) and O-pinacolyl O'-(2-amino)ethyl methylphosphonate (GD-MEA adduct). The samples were prepared by dilution of the reaction masses with deionized water before analysis by CE/indirect UV detection or CE/conductivity detection. Migration time precision was less than 4.0% RSD for IMPA and 5.0 RSD for PMPA on a day-to-day basis. The detection limit for both IMPA and PMPA is 100 micrograms/L; the quantitation limit for both is 500 micrograms/L. For calibration standards, IMPA and PMPA gave a linear response (R2 = 0.9999) over the range 0.5-100 micrograms/mL. The interday precision RSDs were 1.9, 1.0, and 0.7% for IMPA at 7.5, 37.5 and 75.0 micrograms/mL, respectively. Corresponding values for PMPA (again, RSD) were 2.9, 1.1, and 1.0% at 7.5, 37.5 and 87.5 micrograms/mL, respectively, as before. Analysis accuracy was assessed by spiking actual neutralization samples with IMPA or PMPA. For IMPA, the seven spike levels used ranged from 20 to 220% of the IMPA background level, and the incremental change in the found IMPA level ranged from 86 to 99 % of the true spiking increment (R2 = 0.9987 for the linear regression). For PMPA, the five spike levels ranged from 10 to 150% of the matrix background level, and similarly, the accuracy obtained ranged from 95 to 97% of the true incremental value (R2 = 0.9999 for the linear regression).