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Papers by Henk Trap

Research paper thumbnail of Semi-continuous High Speed Gas Analysis of Generated Vapors of Chemical Warfare Agents

Journal of High Resolution Chromatography, 1999

ABSTRACT A method is presented for the continuous analysis of generated vapors of the nerve agent... more ABSTRACT A method is presented for the continuous analysis of generated vapors of the nerve agents soman and sarin and the blistering agent sulfur mustard. By using a gas sampling valve and a very short (15 cm) column connected to an on-column injector with a “standard length” column, the system can either be calibrated or used for performing high speed gas analyses. When using a flame ionization detector, the detection limit was ca. 100 ppb (ca. 0.5–1.0 mg/m3). This technique is applied in inhalation toxicokinetic studies of nerve agents and mustard gas in the guinea pig.

Research paper thumbnail of Intravenous and Inhalation Toxicokinetics of Sarin Stereoisomers in Atropinized Guinea Pigs

Toxicology and Applied Pharmacology, Dec 15, 2000

We report the first toxicokinetic studies of (+/-)-sarin. The toxicokinetics of the stereoisomers... more We report the first toxicokinetic studies of (+/-)-sarin. The toxicokinetics of the stereoisomers of this nerve agent were studied in anesthetized, atropinized, and restrained guinea pigs after intravenous bolus administration of a dose corresponding to 0.8 LD50 and after nose-only exposure to vapor concentrations yielding 0.4 and 0.8 LCt50 in an 8-min exposure time. During exposure the respiratory minute volume and frequency were monitored. Blood samples were taken for gas chromatographic analysis of the nerve agent stereoisomers and for measurement of the activity of blood acetylcholinesterase (AChE). In all experiments, the concentration of (+)-sarin was below the detection limit (<5 pg/ml). The concentration-time profile of the toxic isomer, i.e., (-)-sarin, after an intravenous bolus was adequately described with a two-exponential equation. (-)-Sarin is distributed ca. 10-fold faster than C(-)P(-)-soman, whereas its elimination proceeds almost 10-fold slower. During nose-only exposure to 0.4 and 0.8 LCt50 of (+/-)-sarin in 8 min, (-)-sarin appeared to be rapidly absorbed. The blood AChE activity decreased during the exposure period to ca. 15 and 70% of control activity, respectively. There were no effects on the respiratory parameters. A significant nonlinearity of the toxicokinetics with dose was observed for the respiratory experiments.

Research paper thumbnail of <title>Chemical warfare agent detection in complex environments with comprehensive two-dimensional gas chromatography</title>

Chemical and Biological Sensing IV, 2003

Comprehensive two-dimensional gas chromatography (GCxGC) is an emerging technology for chemical s... more Comprehensive two-dimensional gas chromatography (GCxGC) is an emerging technology for chemical separation that provides an order-of-magnitude increase in separation capacity over traditional gas chromatography. GCxGC separates chemical species with two capillary columns interfaced by two-stage thermal desorption. Because GCxGC is comprehensive and has high separation capacity, it can perform multiple traditional analytical methods with a single analysis. GCxGC has great potential for a wide variety of environmental sensing applications, including detection of chemical warfare agents (CWA) and other harmful chemicals.

Research paper thumbnail of Chapter 4 - MONITORING OF AIR IN CONFINED AND OPEN SPACES

Recent military operations have highlighted the problem of possible chemical hazard exposure in t... more Recent military operations have highlighted the problem of possible chemical hazard exposure in troops. A risk assessment process is especially important for military forces deployed in chemically contaminated environments, and measurement of exposures will help in preventing or reducing incapacitation during deployment or development of disease after deployment [1 -4]. Therefore, a need exists in operational military settings to rapidly detect a wide range of chemicals with potential adverse health effects for exposed personnel. Exposure to airborne contaminants that arise from occupational military activities and local environmental pollution is a major contributor to health problems. Inhalation of gases, vapors, aerosols, and mixtures of these can cause a wide range of adverse health effects, ranging from simple irritation to debilitating systemic diseases. In operational military settings, monitoring of levels of hazardous air pollutants at deployment sites occurs before and during deployment. Insight into the quality of the air at the deployment location is of particular importance, since whereas one may choose to import drinking water and food from the homeland one has to breathe the air that is locally present. It is unlikely that military missions of several months will be fulfilled while continuously wearing respiratory protection.

Research paper thumbnail of Inhalation and Percutaneous Toxicokinetics of Sulfur Mustard and Its Adducts in Hairless Guinea Pigs and Marmosets. Efficacy of Naval Scavengers

As a follow-up to contract DAMD17-94-V-4O09, the inhalation toxicokinetics of sulfur mustard were... more As a follow-up to contract DAMD17-94-V-4O09, the inhalation toxicokinetics of sulfur mustard were studied in more detail in the hairless guinea pig as well as in the marmoset. Hairless guinea pigs were 5-min nose-only exposed to 0.3 and 1 LCt5O. The distribution of sulfurmustard in the respiratory tract was measured at various time-points after exposure. The DNA- adduct levels increased and subsequently decreased with time. The highest levels were found in the upper airways. Marmosets were 5-min nose-only exposed to 160 mg.m(exp -3) sulfur mustard vapor in air, corresponding with 1 LCt5O in the hairless guinea pig. Sulfur mustard was easily measurable in blood during the absorption phase, reaching a maximum concentration of ca. 30 ng.ml(exp -1) at the end of the exposure period. The post-exposure concentration-time course could be described with a hi-exponential equation. The highest concentrations of intact sulfur mustard were found in bone marrow, liver and fat tissue, whereas the...

Research paper thumbnail of Low Level Nose-Only Exposure to the Nerve Agent Soman: Toxicokinetics of Soman Stereoisomers and Cholinesterase Inhibition in Atropinized Guinea Pigs

Toxicology and Applied Pharmacology, 1998

In order to initiate a quantitative basis for the toxicology of low level exposure to nerve agent... more In order to initiate a quantitative basis for the toxicology of low level exposure to nerve agents, the toxicokinetics of soman stereoisomers during nose-only exposure for 5 h to 20 ppb (160 g/m 3 ) of C(؎)P(؎)-soman in air were studied in restrained, anesthetized, and atropinized guinea pigs. The concentrations of the toxic C(؎)P(-)-soman stereoisomers in blood increased according to a biexponential function, after an initial lag time of ca. 30 min for C(؉)P(؊)-soman, with final concentrations < 36 pg/ml. It is hypothesized that the lag time is due to binding to carboxylesterases (CaE), partly in the airways prior to systemic uptake. The gradual inhibition of acetylcholinesterase (AChE) in erythrocytes during the exposure appeared to be in satisfactory accordance with the observed levels of the C(؎)P(؊)-soman stereoisomers in blood. Inhibition of AChE in brain and diaphragm is insignificant at the end of the exposure period. This result suggests that neuropsychological disorders are unlikely to develop in this exposure scenario. However, incapacitating miosis due to direct penetration of nerve agent into the eye would probably occur. Our experiments should be reconsidered for exposure of primates, which lack scavenging CaE in their blood. It is argued that the same challenge level in primates might give rise to higher blood levels of C(؎)P(؊)-soman stereoisomers and concomitantly higher inhibition levels of AChE. Therefore, the critical Ct (mg ⅐ min/m 3 ) values for nonsystemic effects on eyes and airways and systemic effects might be less divergent than in guinea pigs.

Research paper thumbnail of Inhalation Toxicokinetics of Soman Stereoisomers in the Atropinized Guinea Pig with Nose-Only Exposure to Soman Vapor

Toxicology and Applied Pharmacology, 1998

1998). Toxicol. Appl. Pharmacol. 151, 79 -87.

Research paper thumbnail of Intravenous and Inhalation Toxicokinetics of Sarin Stereoisomers in Atropinized Guinea Pigs

Toxicology and Applied Pharmacology, 2000

We report the first toxicokinetic studies of (+/-)-sarin. The toxicokinetics of the stereoisomers... more We report the first toxicokinetic studies of (+/-)-sarin. The toxicokinetics of the stereoisomers of this nerve agent were studied in anesthetized, atropinized, and restrained guinea pigs after intravenous bolus administration of a dose corresponding to 0.8 LD50 and after nose-only exposure to vapor concentrations yielding 0.4 and 0.8 LCt50 in an 8-min exposure time. During exposure the respiratory minute volume and frequency were monitored. Blood samples were taken for gas chromatographic analysis of the nerve agent stereoisomers and for measurement of the activity of blood acetylcholinesterase (AChE). In all experiments, the concentration of (+)-sarin was below the detection limit (&amp;amp;lt;5 pg/ml). The concentration-time profile of the toxic isomer, i.e., (-)-sarin, after an intravenous bolus was adequately described with a two-exponential equation. (-)-Sarin is distributed ca. 10-fold faster than C(-)P(-)-soman, whereas its elimination proceeds almost 10-fold slower. During nose-only exposure to 0.4 and 0.8 LCt50 of (+/-)-sarin in 8 min, (-)-sarin appeared to be rapidly absorbed. The blood AChE activity decreased during the exposure period to ca. 15 and 70% of control activity, respectively. There were no effects on the respiratory parameters. A significant nonlinearity of the toxicokinetics with dose was observed for the respiratory experiments.

Research paper thumbnail of Long-term, low-level exposure of guinea pigs and marmosets to sarin vapor in air: lowest observable effect level

Toxicology and Applied Pharmacology, 2003

Realistic scenarios for low-level exposure to nerve agents will often involve exposures over seve... more Realistic scenarios for low-level exposure to nerve agents will often involve exposures over several hours to extremely low doses of agent. In order to expose animals to the lowest controllable concentrations of agent and to increase exposure times until a lowest observable effect level (LOEL) becomes measurable, a validated system was developed for exposing conscious animals to 0.05-1.0 microg/m(3) (8-160 ppt) of sarin and other nerve agents. Based on cold trapping of sarin from the exposure air, the concentration could be measured semicontinuously, at 4-min time intervals by means of gas chromatography. We found that the LOEL upon a 5-h whole body exposure of guinea pigs and marmosets to sarin vapor corresponds with the measurement of an internal dose by means of fluoride-induced regeneration of sarin from phosphylated binding sites in plasma, mostly BuChE. For guinea pigs the LOEL was observed at Ct = 0.010 +/- 0.002 mg/min/m(3), whereas a Ct of 0.04 +/- 0.01 mg/min/m(3) was established for the LOEL in marmosets. These levels are several orders of magnitude lower than those based on classical measurement of depressed cholinesterase activities. At low exposure levels of guinea pigs and marmosets (&amp;amp;amp;amp;amp;amp;amp;amp;lt; or =1 microg/m(3)), a reasonable linearity was observed between exposure dose and internal dose. The data were addressed in the light of the recently recommended occupational exposure limits to sarin for workers without respiratory protection, which suggests that the exposure limits should be reconsidered if the slightest inhibition of cholinesterases should be prevented.

Research paper thumbnail of Soman levels in kidney and urine following administration to rat, guinea pig, and marmoset

Life Sciences, 1992

Concentrations of C(+/-)P(+/-)-soman (1,2,2-trimethylpropyl methylphosphonofluoridate) in urine o... more Concentrations of C(+/-)P(+/-)-soman (1,2,2-trimethylpropyl methylphosphonofluoridate) in urine of anaesthetized, atropinized and artificially ventilated rats, guinea pigs and marmosets were determined 1-4 h after iv administration of 1-6 LD50 of the agent and in the kidneys 1 h after iv administration of 2-6 LD50 14C-C(+/-)P(+/-)-soman. The concentrations of the toxic C(+/-)P(-)-isomers in both urine and kidneys of the rat were at least two orders of magnitude higher than the corresponding levels in the two other species. Relatively high urine concentrations were also found for C(+/-)P(+/-)-soman-intoxicated (6 LD50) rats pretreated with the nontoxic soman analogue PDP (1,2,2-trimethyl dimethylphosphinate), which considerably decreases the persistence of C(+/-)P(-)-soman in rats, or the carboxylesterase inhibitor CBDP [2-(o-cresyl)-4H-1:3:2-benzodioxaphosphorin-2-oxide]. The lethal effect brought about by intravesical administration of C(+/-)P(+/-)-soman in rats showed that the agent can easily be reabsorbed from the bladder. It is concluded, that this reabsorption does probably not explain the previously observed persistence and &amp;amp;quot;late toxicity&amp;amp;quot; of C(+/-)P(+/-)-soman in rats, although the amount of renally excreted C(+/-)P(-)-soman (ca. 1% of the administered dose) should be sufficient for a toxicologically significant effect.

Research paper thumbnail of Comprehensive gas chromatography with Time of Flight MS and large volume introduction for the detection of fluoride-induced regenerated nerve agent in biological samples

Journal of Chromatography B, 2010

Recently, several methods have been developed to verify exposure to nerve agents. Most of these m... more Recently, several methods have been developed to verify exposure to nerve agents. Most of these methods, such as the fluoride reactivation technique and the analysis of inhibited phosphonylated butyrylcholinesterase (BuChE), are based on mass spectrometry. The high specificity of the mass spectrometer might also imply a disadvantage, because the acquisition mass, i.e. the identity of the analyte must be known beforehand in order to direct the MS analysis in the most sensitive mode. In real cases, the identity of the nerve agent is not always known beforehand and the mass spectrometer should be operated in a scanning mode, with the consequence that sensitivity of the method will be lower. Comprehensive GC, or GC x GC, is a technique which offers enhanced separation. The implied larger selectivity of the GC separation allows mass spectrometry to be conducted in a less specific, scanning, mode. By the use of this configuration, the identity of the nerve agent does not have to be known beforehand but can be traced. In order to be able to detect lower concentrations and assess lower exposure levels, a large volume injection technique was developed allowing sample sizes up to 100 microL. The technique was tested with plasma samples that had been inhibited with various nerve agents. Subsequently, the cholinesterase-bound nerve agent was regenerated by the fluoride reactivation technique. Using the newly developed comprehensive GC-MS method it was possible to detect nerve agent at an exposure level of 1% BuChE inhibition, which is approximately 70 pg nerve agent/mL. These low exposure levels cannot be verified with a cholinesterase (ChE) activity assay. Moreover, the identity of the regenerated nerve agent was verified by the mass spectrum that was generated by the TOF mass spectrometer. This paper presents a technique able to deliver full-scan data on the analysis of nerve agents in biomedical samples at relevant exposure levels (1% BuChE inhibition). This full-scan data meets for a large part the forensic requirements that are in place for the analysis of biomedical samples in the context of alleged use of Chemical Warfare Agents.

Research paper thumbnail of Selective and sensitive trace analysis of sulfur mustard with thermal desorption and two-dimensional gas chromatography–mass spectrometry

Journal of Chromatography A, 2007

An improved method is presented for the trace analysis of sulfur mustard (HD) in biological sampl... more An improved method is presented for the trace analysis of sulfur mustard (HD) in biological samples, such as blood and tissue from laboratory animals. Using the internal standard method and liquid-liquid extraction with ethyl acetate, up to 400 microL of the extract was injected by thermal desorption from Tenax and analyzed by two-dimensional GC-MS/EI in SIM mode. The analysis was compared with a direct GC injection. Reversed thermal desorption was used as a tool for handling heavily contaminated (fat) samples, thus preventing contamination of the injection system and pre-column. A successful analytical configuration has been set up for the bioanalysis of HD at the low, toxicologically relevant pM level. A detection limit of 10 pg mL(-1) blood or pg g(-1) tissue of sulfur mustard (S/N=3) was established by using this configuration.

Research paper thumbnail of Low-level exposure of guinea pigs and marmosets to sarin vapour in air: lowest-observable-adverse-effect level(LOAEL) for miosis

Journal of Applied Toxicology, 2004

The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs ... more The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs and marmoset monkeys to sarin vapour in air, the lowest-observable-adverse-effect level (LOAEL) of sarin for miosis. This is the concentration x time (C.t) value (t = 5 h) of exposure at which miosis becomes significant. The ratio of pupil and iris diameters, measured on digital photographs taken on-line during exposure, was calculated as a measure for miosis. The exposure concentrations were in the range 7-150 microg x m(-3) and the exposure times needed to achieve significant miosis were in the range 10-300 min. Both vehicle- and pyridostigmine-pretreated animals were used in the experiments. The latter pretreatment resulted in ca. 30% inhibition of erythrocyte acetylcholinesterase in both species. In vehicle-pretreated guinea pigs and marmosets the pupil size was decreased significantly (P &amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) at sarin doses of 1.8 +/- 0.3 and 2.5 +/- 0.8 mg x min x m(-3), respectively. In pyridostigmine-pretreated guinea pigs and marmosets the pupil size was affected significantly (P &amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) at 1.8 +/- 0.5 and 3.0 +/- 0.8 mg x min x m(-3), respectively. Evidently there is no significant influence of pyridostigmine pretreatment on the LOAEL. These data were addressed in light of the recommended occupational and detection limits for sarin vapour in air. It was concluded that miosis will occur during low-level sarin exposure at levels that are not detectable by the currently fielded alarm systems, assuming that humans are as sensitive for sarin vapour in air as guinea pigs and marmosets.

Research paper thumbnail of Bioanalysis of the Enantiomers of ( )-Sarin using Automated Thermal Cold-Trap Injection Combined with Two-Dimensional Gas Chromatography

Journal of Analytical Toxicology, 2001

A fully automated multidimensional gas chromatographic system with thermal desorption injection a... more A fully automated multidimensional gas chromatographic system with thermal desorption injection and alkali flame detection was developed for analysis of the enantiomers of the nerve agent (+/-)-sarin. The chiral stationary phase was CP Cyclodex B on which the sarin enantiomers were completely resolved. The absolute detection limit was 2.5 pg per enantiomer. The method is intended to be used for the analysis of the sarin enantiomers in biological samples. For this purpose, sarin was isolated from guinea pig blood via solid-phase extraction. Deuterated sarin was used as internal standard. Stabilization of sarin in the blood sample by acidification and addition of an excess of a competitive organophosphorus compound (neopentyl sarin) appeared to be essential. The absolute recovery of the extraction procedure was 60%, whereas the recovery relative to the internal standard was 100%.

Research paper thumbnail of Toxicokinetics of Sulfur Mustard and its Dna-Adducts in the Hairless Guinea Pig

Drug and Chemical Toxicology, 1998

In order to provide a quantitative basis for pretreatment and therapy of intoxications with sulfu... more In order to provide a quantitative basis for pretreatment and therapy of intoxications with sulfur mustard (SM) the toxicokinetics of this agent as well as its major DNA-adduct (7-SM-gua) were studied in male hairless guinea pigs for the respiratory and percutaneous routes. The study comprised measurement of the concentration-time course of SM in blood and measurement of the concentrations of intact SM and 7-SM-gua in various tissues at several time points after exposure to SM. SM was analyzed in blood and tissues by GC-MS, whereas 7-SM-gua was measured via an immuno-slot-blot method. During and after 5-min nose-only exposure of anesthetized, restrained hairless guinea pigs to a dose of SM corresponding with 1 LCt50 (800 mg.min.m -3 ), the intact agent could not be detected in blood, whereas 7-SM-gua was barely detectable in blood and lung. In agreement herewith, we observed that most DNA-adduct formation in the respiratory tract of the exposed hairless guinea pigs had occurred in the larynx and trachea. Furthermore, histopathological evaluation of the respiratory tract of these animals revealed damage mainly located in the upper airways, with hardly any damage in the lungs. SM was measurable in blood during and after 8-min nose-only exposure of hairless guinea pigs to a Ct of 2,400 mg.min.m -3 (3 LCt50). The shape of the concentration-time profile of SM in blood indicates the existence of two absorption processes, i.e., a very rapid one and a slow one. Concentrations of intact SM in tissues were very low. Measurable concentrations of 7-SM-gua were only observed in the blood and the lungs of the exposed animals. The results of the respiratory toxicokinetic studies suggest that the adverse effects due to respiratory exposure to SM appear to be more of a local than of a systemic nature, at least in the hairless guinea pig. In order to improve the protection against the respiratory effects of SM, the uptake and distribution of SM after nose-only exposure need to be studied further in various species. During and after a 45-min percutaneous exposure of anesthetized, restrained hairless guinea pigs to SM vapor, yielding a Ct of ca. 10,000 mg.min.m -3 (ca. 1 percutaneous LCt50), SM could be detected in the blood. The concentration-time profile in blood suggests the existence of a rapid and a slow absorption process. Shortly after ending the exposure, concentrations of intact SM exceeding that in blood were measured in the tissues. Rather low concentrations of 7-SM-gua were measured in most tissues. On the basis of these studies, it was concluded that in the hairless guinea pig a systemic intoxication with SM is more likely to occur from a percutaneous exposure than from a nose-only exposure.

Research paper thumbnail of Monitoring of in Vitro and in Vivo Exposure to Sulfur Mustard by GC/MS Determination of the N-Terminal Valine Adduct in Hemoglobin after a Modified Edman Degradation

Chemical Research in Toxicology, 1996

We report that exposure to the chemical warfare agent sulfur mustard can be monitored by means of... more We report that exposure to the chemical warfare agent sulfur mustard can be monitored by means of a modified Edman degradation involving selective release of the N-terminal valine adduct of hemoglobin with the agent. The degree of alkylation of the N-terminal valine in human hemoglobin is approximately 1-2% of the total alkylation induced in hemoglobin upon treatment of human blood with sulfur mustard. After modified Edman degradation, followed by derivatization with heptafluorobutyric anhydride, the obtained pentafluorophenyl thiohydantion derivative of the valine adduct could be analyzed at a g0.5 fmol level by means of GC/MS under negative ion chemical ionization conditions. Applying this procedure, in vitro exposure of human blood to g0.1 µM of sulfur mustard could be determined. In vivo exposure of guinea pigs could also be established at 48 h after intoxication intravenously with 0.5 mg/ kg (0.06 LD 50 ) of the agent.

Research paper thumbnail of Synthesis and mass spectrometric identification of the major amino acid adducts formed between sulphur mustard and haemoglobin in human blood

Archives of Toxicology, 1997

As part of a program to develop methods for the verification of alleged exposure to sulphur musta... more As part of a program to develop methods for the verification of alleged exposure to sulphur mustard, we synthesized and characterized three amino acid adducts presumably formed by alkylation of haemoglobin: 4-(2-hydroxyethylthioethyl)-L L -aspartate, 5-(2-hydroxyethylthioethyl)-L L -glutamate and N1-and N3-(2-hydroxyethylthioethyl)-L L -histidine. Suitable derivatization methods for GC/MS analysis were developed for these adducts as well as for the cysteine and the N-terminal valine adduct. Incubation of human blood with [ 35 S]sulphur mustard in vitro followed by acidic hydrolysis of isolated globin and derivatization with Fmoc-Cl afforded three major radioactive peaks upon HPLC analysis, one of which coeluted with the synthetic Fmoc derivative of N1/N3-(2-hydroxyethylthioethyl)-L L -histidine. After pronase digestion of globin the adducts of histidine, glutamic acid, aspartic acid, cysteine and Nterminal valine could be tentatively identified and quantitated. Final identification was obtained from GC/ MS analysis. The most abundant adduct, N1/N3-(2hydroxyethylthioethyl)-L L -histidine, could not be sensitively analysed by GC/MS. A convenient LC-tandem MS procedure was developed for this compound, enabling the detection of exposure of human blood to 10 M sulphur mustard in vitro.

Research paper thumbnail of Toxicokinetics of soman stereoisomers after subcutaneous administration to atropinized guinea pigs

Archives of Toxicology, 1994

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investiga... more The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investigated after subcutaneous administration of a 6 LD50 dose (148 micrograms/kg) to anaesthetized, atropinized, and artificially ventilated guinea pigs. Whereas the relatively nontoxic C(+/-)P(+)-isomers were not detected in blood, the highly toxic C(+/-)P(-)-isomers appeared within 1 min in the general circulation and reached maximum levels of 10-15 ng/ml blood within a period of ca. 7 min. In this absorption phase the blood levels of the C(+)P(-)-isomer lag clearly behind those of the C(-)P(-)-isomer. The blood levels of both C(+/-)P(-)-isomers could be mathematically described using non-linear regression by a three-exponential equation, with one exponential term describing the rapid absorption phase and the other two terms describing distribution and elimination. A comparison with the toxicokinetics of the same isomers upon intravenous administration of the same dose shows that the systemic availability upon subcutaneous administration is in the range of 74-83%. Toxicologically relevant concentrations of the C(+/-)P(-)-isomers prevail almost twice as long after subcutaneous than after intravenous administration. From a toxicokinetic point of view, subcutaneous administration of C(+/-)P(+/-)-soman appears not to be a realistic model for the most relevant route of exposure to C(+/-)P(+/-)-soman in case of chemical warfare, i.e. short term respiratory exposure.

Research paper thumbnail of Effect of pretreatment with CBDP on the toxicokinetics of soman stereoisomers in rats and guinea pigs

Archives of Toxicology, 1993

Pretreatment of rats and guinea pigs with the specific carboxylesterase inhibitor 2-(o-cresyl)-4H... more Pretreatment of rats and guinea pigs with the specific carboxylesterase inhibitor 2-(o-cresyl)-4H-1:3:2-benzodioxaphosphorin-2-oxide (CBDP) reduces the LD50 of the nerve agent C(+/-)P(+/-)-soman in these species to the same range as in primates. This suggests that such CBDP-pretreated animals can be used in investigations that are relevant for prophylaxis and therapy of intoxication with C(+/-)P(+/-)-soman in primates including humans. In order to test this hypothesis we have studied the toxicokinetics of the toxic C(+/-)P(-)-isomers of soman in artificially respirated and CBDP-pretreated rats and guinea pigs at intravenous doses corresponding to 6x LD50. A comparison of the areas under the curve (AUCs) of the blood levels of C(+/-)P(-)-soman in pretreated and non-pretreated animals at the same absolute dose shows extreme nonlinearity with dose, indicating that CBDP occupies highly reactive binding sites which are no longer available for sequestration of the soman isomers. The AUCs of C(+/-)P(-)-soman at equitoxic doses of 6x LD50 are reduced by pretreatment with CBDP from 1683 to 464 ng.min.ml-1 in rats and from 978 to 176 ng.min.ml-1 in guinea pigs, which is in the range of the AUC in non-pretreated marmosets at an equitoxic dose (419 ng.min.ml-1). The blood levels of the C(+/-)P(-)-isomers in marmosets and CBDP rats are rather similar during the first 7 min, but persist in CBDP rats for 2 h longer at toxicologically relevant levels than in marmosets.(ABSTRACT TRUNCATED AT 250 WORDS)

Research paper thumbnail of Chemical and Biological Sensing IV (Proceedings Volume)

* Available as a photocopy reprint only. Allow two weeks reprinting time plus standard delivery t... more * Available as a photocopy reprint only. Allow two weeks reprinting time plus standard delivery time. No discounts or returns apply. ... Standard delivery in the US is 7 to 10 business days and outside the US delivery is 4 to 6 weeks or longer. For further details, please see shipping policy. ... Listed below are the papers found in this volume. Click the paper title to view an abstract or to order an individual paper. ... Sign up for monthly alerts of new titles released.

Research paper thumbnail of Semi-continuous High Speed Gas Analysis of Generated Vapors of Chemical Warfare Agents

Journal of High Resolution Chromatography, 1999

ABSTRACT A method is presented for the continuous analysis of generated vapors of the nerve agent... more ABSTRACT A method is presented for the continuous analysis of generated vapors of the nerve agents soman and sarin and the blistering agent sulfur mustard. By using a gas sampling valve and a very short (15 cm) column connected to an on-column injector with a “standard length” column, the system can either be calibrated or used for performing high speed gas analyses. When using a flame ionization detector, the detection limit was ca. 100 ppb (ca. 0.5–1.0 mg/m3). This technique is applied in inhalation toxicokinetic studies of nerve agents and mustard gas in the guinea pig.

Research paper thumbnail of Intravenous and Inhalation Toxicokinetics of Sarin Stereoisomers in Atropinized Guinea Pigs

Toxicology and Applied Pharmacology, Dec 15, 2000

We report the first toxicokinetic studies of (+/-)-sarin. The toxicokinetics of the stereoisomers... more We report the first toxicokinetic studies of (+/-)-sarin. The toxicokinetics of the stereoisomers of this nerve agent were studied in anesthetized, atropinized, and restrained guinea pigs after intravenous bolus administration of a dose corresponding to 0.8 LD50 and after nose-only exposure to vapor concentrations yielding 0.4 and 0.8 LCt50 in an 8-min exposure time. During exposure the respiratory minute volume and frequency were monitored. Blood samples were taken for gas chromatographic analysis of the nerve agent stereoisomers and for measurement of the activity of blood acetylcholinesterase (AChE). In all experiments, the concentration of (+)-sarin was below the detection limit (&amp;amp;lt;5 pg/ml). The concentration-time profile of the toxic isomer, i.e., (-)-sarin, after an intravenous bolus was adequately described with a two-exponential equation. (-)-Sarin is distributed ca. 10-fold faster than C(-)P(-)-soman, whereas its elimination proceeds almost 10-fold slower. During nose-only exposure to 0.4 and 0.8 LCt50 of (+/-)-sarin in 8 min, (-)-sarin appeared to be rapidly absorbed. The blood AChE activity decreased during the exposure period to ca. 15 and 70% of control activity, respectively. There were no effects on the respiratory parameters. A significant nonlinearity of the toxicokinetics with dose was observed for the respiratory experiments.

Research paper thumbnail of <title>Chemical warfare agent detection in complex environments with comprehensive two-dimensional gas chromatography</title>

Chemical and Biological Sensing IV, 2003

Comprehensive two-dimensional gas chromatography (GCxGC) is an emerging technology for chemical s... more Comprehensive two-dimensional gas chromatography (GCxGC) is an emerging technology for chemical separation that provides an order-of-magnitude increase in separation capacity over traditional gas chromatography. GCxGC separates chemical species with two capillary columns interfaced by two-stage thermal desorption. Because GCxGC is comprehensive and has high separation capacity, it can perform multiple traditional analytical methods with a single analysis. GCxGC has great potential for a wide variety of environmental sensing applications, including detection of chemical warfare agents (CWA) and other harmful chemicals.

Research paper thumbnail of Chapter 4 - MONITORING OF AIR IN CONFINED AND OPEN SPACES

Recent military operations have highlighted the problem of possible chemical hazard exposure in t... more Recent military operations have highlighted the problem of possible chemical hazard exposure in troops. A risk assessment process is especially important for military forces deployed in chemically contaminated environments, and measurement of exposures will help in preventing or reducing incapacitation during deployment or development of disease after deployment [1 -4]. Therefore, a need exists in operational military settings to rapidly detect a wide range of chemicals with potential adverse health effects for exposed personnel. Exposure to airborne contaminants that arise from occupational military activities and local environmental pollution is a major contributor to health problems. Inhalation of gases, vapors, aerosols, and mixtures of these can cause a wide range of adverse health effects, ranging from simple irritation to debilitating systemic diseases. In operational military settings, monitoring of levels of hazardous air pollutants at deployment sites occurs before and during deployment. Insight into the quality of the air at the deployment location is of particular importance, since whereas one may choose to import drinking water and food from the homeland one has to breathe the air that is locally present. It is unlikely that military missions of several months will be fulfilled while continuously wearing respiratory protection.

Research paper thumbnail of Inhalation and Percutaneous Toxicokinetics of Sulfur Mustard and Its Adducts in Hairless Guinea Pigs and Marmosets. Efficacy of Naval Scavengers

As a follow-up to contract DAMD17-94-V-4O09, the inhalation toxicokinetics of sulfur mustard were... more As a follow-up to contract DAMD17-94-V-4O09, the inhalation toxicokinetics of sulfur mustard were studied in more detail in the hairless guinea pig as well as in the marmoset. Hairless guinea pigs were 5-min nose-only exposed to 0.3 and 1 LCt5O. The distribution of sulfurmustard in the respiratory tract was measured at various time-points after exposure. The DNA- adduct levels increased and subsequently decreased with time. The highest levels were found in the upper airways. Marmosets were 5-min nose-only exposed to 160 mg.m(exp -3) sulfur mustard vapor in air, corresponding with 1 LCt5O in the hairless guinea pig. Sulfur mustard was easily measurable in blood during the absorption phase, reaching a maximum concentration of ca. 30 ng.ml(exp -1) at the end of the exposure period. The post-exposure concentration-time course could be described with a hi-exponential equation. The highest concentrations of intact sulfur mustard were found in bone marrow, liver and fat tissue, whereas the...

Research paper thumbnail of Low Level Nose-Only Exposure to the Nerve Agent Soman: Toxicokinetics of Soman Stereoisomers and Cholinesterase Inhibition in Atropinized Guinea Pigs

Toxicology and Applied Pharmacology, 1998

In order to initiate a quantitative basis for the toxicology of low level exposure to nerve agent... more In order to initiate a quantitative basis for the toxicology of low level exposure to nerve agents, the toxicokinetics of soman stereoisomers during nose-only exposure for 5 h to 20 ppb (160 g/m 3 ) of C(؎)P(؎)-soman in air were studied in restrained, anesthetized, and atropinized guinea pigs. The concentrations of the toxic C(؎)P(-)-soman stereoisomers in blood increased according to a biexponential function, after an initial lag time of ca. 30 min for C(؉)P(؊)-soman, with final concentrations < 36 pg/ml. It is hypothesized that the lag time is due to binding to carboxylesterases (CaE), partly in the airways prior to systemic uptake. The gradual inhibition of acetylcholinesterase (AChE) in erythrocytes during the exposure appeared to be in satisfactory accordance with the observed levels of the C(؎)P(؊)-soman stereoisomers in blood. Inhibition of AChE in brain and diaphragm is insignificant at the end of the exposure period. This result suggests that neuropsychological disorders are unlikely to develop in this exposure scenario. However, incapacitating miosis due to direct penetration of nerve agent into the eye would probably occur. Our experiments should be reconsidered for exposure of primates, which lack scavenging CaE in their blood. It is argued that the same challenge level in primates might give rise to higher blood levels of C(؎)P(؊)-soman stereoisomers and concomitantly higher inhibition levels of AChE. Therefore, the critical Ct (mg ⅐ min/m 3 ) values for nonsystemic effects on eyes and airways and systemic effects might be less divergent than in guinea pigs.

Research paper thumbnail of Inhalation Toxicokinetics of Soman Stereoisomers in the Atropinized Guinea Pig with Nose-Only Exposure to Soman Vapor

Toxicology and Applied Pharmacology, 1998

1998). Toxicol. Appl. Pharmacol. 151, 79 -87.

Research paper thumbnail of Intravenous and Inhalation Toxicokinetics of Sarin Stereoisomers in Atropinized Guinea Pigs

Toxicology and Applied Pharmacology, 2000

We report the first toxicokinetic studies of (+/-)-sarin. The toxicokinetics of the stereoisomers... more We report the first toxicokinetic studies of (+/-)-sarin. The toxicokinetics of the stereoisomers of this nerve agent were studied in anesthetized, atropinized, and restrained guinea pigs after intravenous bolus administration of a dose corresponding to 0.8 LD50 and after nose-only exposure to vapor concentrations yielding 0.4 and 0.8 LCt50 in an 8-min exposure time. During exposure the respiratory minute volume and frequency were monitored. Blood samples were taken for gas chromatographic analysis of the nerve agent stereoisomers and for measurement of the activity of blood acetylcholinesterase (AChE). In all experiments, the concentration of (+)-sarin was below the detection limit (&amp;amp;lt;5 pg/ml). The concentration-time profile of the toxic isomer, i.e., (-)-sarin, after an intravenous bolus was adequately described with a two-exponential equation. (-)-Sarin is distributed ca. 10-fold faster than C(-)P(-)-soman, whereas its elimination proceeds almost 10-fold slower. During nose-only exposure to 0.4 and 0.8 LCt50 of (+/-)-sarin in 8 min, (-)-sarin appeared to be rapidly absorbed. The blood AChE activity decreased during the exposure period to ca. 15 and 70% of control activity, respectively. There were no effects on the respiratory parameters. A significant nonlinearity of the toxicokinetics with dose was observed for the respiratory experiments.

Research paper thumbnail of Long-term, low-level exposure of guinea pigs and marmosets to sarin vapor in air: lowest observable effect level

Toxicology and Applied Pharmacology, 2003

Realistic scenarios for low-level exposure to nerve agents will often involve exposures over seve... more Realistic scenarios for low-level exposure to nerve agents will often involve exposures over several hours to extremely low doses of agent. In order to expose animals to the lowest controllable concentrations of agent and to increase exposure times until a lowest observable effect level (LOEL) becomes measurable, a validated system was developed for exposing conscious animals to 0.05-1.0 microg/m(3) (8-160 ppt) of sarin and other nerve agents. Based on cold trapping of sarin from the exposure air, the concentration could be measured semicontinuously, at 4-min time intervals by means of gas chromatography. We found that the LOEL upon a 5-h whole body exposure of guinea pigs and marmosets to sarin vapor corresponds with the measurement of an internal dose by means of fluoride-induced regeneration of sarin from phosphylated binding sites in plasma, mostly BuChE. For guinea pigs the LOEL was observed at Ct = 0.010 +/- 0.002 mg/min/m(3), whereas a Ct of 0.04 +/- 0.01 mg/min/m(3) was established for the LOEL in marmosets. These levels are several orders of magnitude lower than those based on classical measurement of depressed cholinesterase activities. At low exposure levels of guinea pigs and marmosets (&amp;amp;amp;amp;amp;amp;amp;amp;lt; or =1 microg/m(3)), a reasonable linearity was observed between exposure dose and internal dose. The data were addressed in the light of the recently recommended occupational exposure limits to sarin for workers without respiratory protection, which suggests that the exposure limits should be reconsidered if the slightest inhibition of cholinesterases should be prevented.

Research paper thumbnail of Soman levels in kidney and urine following administration to rat, guinea pig, and marmoset

Life Sciences, 1992

Concentrations of C(+/-)P(+/-)-soman (1,2,2-trimethylpropyl methylphosphonofluoridate) in urine o... more Concentrations of C(+/-)P(+/-)-soman (1,2,2-trimethylpropyl methylphosphonofluoridate) in urine of anaesthetized, atropinized and artificially ventilated rats, guinea pigs and marmosets were determined 1-4 h after iv administration of 1-6 LD50 of the agent and in the kidneys 1 h after iv administration of 2-6 LD50 14C-C(+/-)P(+/-)-soman. The concentrations of the toxic C(+/-)P(-)-isomers in both urine and kidneys of the rat were at least two orders of magnitude higher than the corresponding levels in the two other species. Relatively high urine concentrations were also found for C(+/-)P(+/-)-soman-intoxicated (6 LD50) rats pretreated with the nontoxic soman analogue PDP (1,2,2-trimethyl dimethylphosphinate), which considerably decreases the persistence of C(+/-)P(-)-soman in rats, or the carboxylesterase inhibitor CBDP [2-(o-cresyl)-4H-1:3:2-benzodioxaphosphorin-2-oxide]. The lethal effect brought about by intravesical administration of C(+/-)P(+/-)-soman in rats showed that the agent can easily be reabsorbed from the bladder. It is concluded, that this reabsorption does probably not explain the previously observed persistence and &amp;amp;quot;late toxicity&amp;amp;quot; of C(+/-)P(+/-)-soman in rats, although the amount of renally excreted C(+/-)P(-)-soman (ca. 1% of the administered dose) should be sufficient for a toxicologically significant effect.

Research paper thumbnail of Comprehensive gas chromatography with Time of Flight MS and large volume introduction for the detection of fluoride-induced regenerated nerve agent in biological samples

Journal of Chromatography B, 2010

Recently, several methods have been developed to verify exposure to nerve agents. Most of these m... more Recently, several methods have been developed to verify exposure to nerve agents. Most of these methods, such as the fluoride reactivation technique and the analysis of inhibited phosphonylated butyrylcholinesterase (BuChE), are based on mass spectrometry. The high specificity of the mass spectrometer might also imply a disadvantage, because the acquisition mass, i.e. the identity of the analyte must be known beforehand in order to direct the MS analysis in the most sensitive mode. In real cases, the identity of the nerve agent is not always known beforehand and the mass spectrometer should be operated in a scanning mode, with the consequence that sensitivity of the method will be lower. Comprehensive GC, or GC x GC, is a technique which offers enhanced separation. The implied larger selectivity of the GC separation allows mass spectrometry to be conducted in a less specific, scanning, mode. By the use of this configuration, the identity of the nerve agent does not have to be known beforehand but can be traced. In order to be able to detect lower concentrations and assess lower exposure levels, a large volume injection technique was developed allowing sample sizes up to 100 microL. The technique was tested with plasma samples that had been inhibited with various nerve agents. Subsequently, the cholinesterase-bound nerve agent was regenerated by the fluoride reactivation technique. Using the newly developed comprehensive GC-MS method it was possible to detect nerve agent at an exposure level of 1% BuChE inhibition, which is approximately 70 pg nerve agent/mL. These low exposure levels cannot be verified with a cholinesterase (ChE) activity assay. Moreover, the identity of the regenerated nerve agent was verified by the mass spectrum that was generated by the TOF mass spectrometer. This paper presents a technique able to deliver full-scan data on the analysis of nerve agents in biomedical samples at relevant exposure levels (1% BuChE inhibition). This full-scan data meets for a large part the forensic requirements that are in place for the analysis of biomedical samples in the context of alleged use of Chemical Warfare Agents.

Research paper thumbnail of Selective and sensitive trace analysis of sulfur mustard with thermal desorption and two-dimensional gas chromatography–mass spectrometry

Journal of Chromatography A, 2007

An improved method is presented for the trace analysis of sulfur mustard (HD) in biological sampl... more An improved method is presented for the trace analysis of sulfur mustard (HD) in biological samples, such as blood and tissue from laboratory animals. Using the internal standard method and liquid-liquid extraction with ethyl acetate, up to 400 microL of the extract was injected by thermal desorption from Tenax and analyzed by two-dimensional GC-MS/EI in SIM mode. The analysis was compared with a direct GC injection. Reversed thermal desorption was used as a tool for handling heavily contaminated (fat) samples, thus preventing contamination of the injection system and pre-column. A successful analytical configuration has been set up for the bioanalysis of HD at the low, toxicologically relevant pM level. A detection limit of 10 pg mL(-1) blood or pg g(-1) tissue of sulfur mustard (S/N=3) was established by using this configuration.

Research paper thumbnail of Low-level exposure of guinea pigs and marmosets to sarin vapour in air: lowest-observable-adverse-effect level(LOAEL) for miosis

Journal of Applied Toxicology, 2004

The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs ... more The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs and marmoset monkeys to sarin vapour in air, the lowest-observable-adverse-effect level (LOAEL) of sarin for miosis. This is the concentration x time (C.t) value (t = 5 h) of exposure at which miosis becomes significant. The ratio of pupil and iris diameters, measured on digital photographs taken on-line during exposure, was calculated as a measure for miosis. The exposure concentrations were in the range 7-150 microg x m(-3) and the exposure times needed to achieve significant miosis were in the range 10-300 min. Both vehicle- and pyridostigmine-pretreated animals were used in the experiments. The latter pretreatment resulted in ca. 30% inhibition of erythrocyte acetylcholinesterase in both species. In vehicle-pretreated guinea pigs and marmosets the pupil size was decreased significantly (P &amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) at sarin doses of 1.8 +/- 0.3 and 2.5 +/- 0.8 mg x min x m(-3), respectively. In pyridostigmine-pretreated guinea pigs and marmosets the pupil size was affected significantly (P &amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05) at 1.8 +/- 0.5 and 3.0 +/- 0.8 mg x min x m(-3), respectively. Evidently there is no significant influence of pyridostigmine pretreatment on the LOAEL. These data were addressed in light of the recommended occupational and detection limits for sarin vapour in air. It was concluded that miosis will occur during low-level sarin exposure at levels that are not detectable by the currently fielded alarm systems, assuming that humans are as sensitive for sarin vapour in air as guinea pigs and marmosets.

Research paper thumbnail of Bioanalysis of the Enantiomers of ( )-Sarin using Automated Thermal Cold-Trap Injection Combined with Two-Dimensional Gas Chromatography

Journal of Analytical Toxicology, 2001

A fully automated multidimensional gas chromatographic system with thermal desorption injection a... more A fully automated multidimensional gas chromatographic system with thermal desorption injection and alkali flame detection was developed for analysis of the enantiomers of the nerve agent (+/-)-sarin. The chiral stationary phase was CP Cyclodex B on which the sarin enantiomers were completely resolved. The absolute detection limit was 2.5 pg per enantiomer. The method is intended to be used for the analysis of the sarin enantiomers in biological samples. For this purpose, sarin was isolated from guinea pig blood via solid-phase extraction. Deuterated sarin was used as internal standard. Stabilization of sarin in the blood sample by acidification and addition of an excess of a competitive organophosphorus compound (neopentyl sarin) appeared to be essential. The absolute recovery of the extraction procedure was 60%, whereas the recovery relative to the internal standard was 100%.

Research paper thumbnail of Toxicokinetics of Sulfur Mustard and its Dna-Adducts in the Hairless Guinea Pig

Drug and Chemical Toxicology, 1998

In order to provide a quantitative basis for pretreatment and therapy of intoxications with sulfu... more In order to provide a quantitative basis for pretreatment and therapy of intoxications with sulfur mustard (SM) the toxicokinetics of this agent as well as its major DNA-adduct (7-SM-gua) were studied in male hairless guinea pigs for the respiratory and percutaneous routes. The study comprised measurement of the concentration-time course of SM in blood and measurement of the concentrations of intact SM and 7-SM-gua in various tissues at several time points after exposure to SM. SM was analyzed in blood and tissues by GC-MS, whereas 7-SM-gua was measured via an immuno-slot-blot method. During and after 5-min nose-only exposure of anesthetized, restrained hairless guinea pigs to a dose of SM corresponding with 1 LCt50 (800 mg.min.m -3 ), the intact agent could not be detected in blood, whereas 7-SM-gua was barely detectable in blood and lung. In agreement herewith, we observed that most DNA-adduct formation in the respiratory tract of the exposed hairless guinea pigs had occurred in the larynx and trachea. Furthermore, histopathological evaluation of the respiratory tract of these animals revealed damage mainly located in the upper airways, with hardly any damage in the lungs. SM was measurable in blood during and after 8-min nose-only exposure of hairless guinea pigs to a Ct of 2,400 mg.min.m -3 (3 LCt50). The shape of the concentration-time profile of SM in blood indicates the existence of two absorption processes, i.e., a very rapid one and a slow one. Concentrations of intact SM in tissues were very low. Measurable concentrations of 7-SM-gua were only observed in the blood and the lungs of the exposed animals. The results of the respiratory toxicokinetic studies suggest that the adverse effects due to respiratory exposure to SM appear to be more of a local than of a systemic nature, at least in the hairless guinea pig. In order to improve the protection against the respiratory effects of SM, the uptake and distribution of SM after nose-only exposure need to be studied further in various species. During and after a 45-min percutaneous exposure of anesthetized, restrained hairless guinea pigs to SM vapor, yielding a Ct of ca. 10,000 mg.min.m -3 (ca. 1 percutaneous LCt50), SM could be detected in the blood. The concentration-time profile in blood suggests the existence of a rapid and a slow absorption process. Shortly after ending the exposure, concentrations of intact SM exceeding that in blood were measured in the tissues. Rather low concentrations of 7-SM-gua were measured in most tissues. On the basis of these studies, it was concluded that in the hairless guinea pig a systemic intoxication with SM is more likely to occur from a percutaneous exposure than from a nose-only exposure.

Research paper thumbnail of Monitoring of in Vitro and in Vivo Exposure to Sulfur Mustard by GC/MS Determination of the N-Terminal Valine Adduct in Hemoglobin after a Modified Edman Degradation

Chemical Research in Toxicology, 1996

We report that exposure to the chemical warfare agent sulfur mustard can be monitored by means of... more We report that exposure to the chemical warfare agent sulfur mustard can be monitored by means of a modified Edman degradation involving selective release of the N-terminal valine adduct of hemoglobin with the agent. The degree of alkylation of the N-terminal valine in human hemoglobin is approximately 1-2% of the total alkylation induced in hemoglobin upon treatment of human blood with sulfur mustard. After modified Edman degradation, followed by derivatization with heptafluorobutyric anhydride, the obtained pentafluorophenyl thiohydantion derivative of the valine adduct could be analyzed at a g0.5 fmol level by means of GC/MS under negative ion chemical ionization conditions. Applying this procedure, in vitro exposure of human blood to g0.1 µM of sulfur mustard could be determined. In vivo exposure of guinea pigs could also be established at 48 h after intoxication intravenously with 0.5 mg/ kg (0.06 LD 50 ) of the agent.

Research paper thumbnail of Synthesis and mass spectrometric identification of the major amino acid adducts formed between sulphur mustard and haemoglobin in human blood

Archives of Toxicology, 1997

As part of a program to develop methods for the verification of alleged exposure to sulphur musta... more As part of a program to develop methods for the verification of alleged exposure to sulphur mustard, we synthesized and characterized three amino acid adducts presumably formed by alkylation of haemoglobin: 4-(2-hydroxyethylthioethyl)-L L -aspartate, 5-(2-hydroxyethylthioethyl)-L L -glutamate and N1-and N3-(2-hydroxyethylthioethyl)-L L -histidine. Suitable derivatization methods for GC/MS analysis were developed for these adducts as well as for the cysteine and the N-terminal valine adduct. Incubation of human blood with [ 35 S]sulphur mustard in vitro followed by acidic hydrolysis of isolated globin and derivatization with Fmoc-Cl afforded three major radioactive peaks upon HPLC analysis, one of which coeluted with the synthetic Fmoc derivative of N1/N3-(2-hydroxyethylthioethyl)-L L -histidine. After pronase digestion of globin the adducts of histidine, glutamic acid, aspartic acid, cysteine and Nterminal valine could be tentatively identified and quantitated. Final identification was obtained from GC/ MS analysis. The most abundant adduct, N1/N3-(2hydroxyethylthioethyl)-L L -histidine, could not be sensitively analysed by GC/MS. A convenient LC-tandem MS procedure was developed for this compound, enabling the detection of exposure of human blood to 10 M sulphur mustard in vitro.

Research paper thumbnail of Toxicokinetics of soman stereoisomers after subcutaneous administration to atropinized guinea pigs

Archives of Toxicology, 1994

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investiga... more The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investigated after subcutaneous administration of a 6 LD50 dose (148 micrograms/kg) to anaesthetized, atropinized, and artificially ventilated guinea pigs. Whereas the relatively nontoxic C(+/-)P(+)-isomers were not detected in blood, the highly toxic C(+/-)P(-)-isomers appeared within 1 min in the general circulation and reached maximum levels of 10-15 ng/ml blood within a period of ca. 7 min. In this absorption phase the blood levels of the C(+)P(-)-isomer lag clearly behind those of the C(-)P(-)-isomer. The blood levels of both C(+/-)P(-)-isomers could be mathematically described using non-linear regression by a three-exponential equation, with one exponential term describing the rapid absorption phase and the other two terms describing distribution and elimination. A comparison with the toxicokinetics of the same isomers upon intravenous administration of the same dose shows that the systemic availability upon subcutaneous administration is in the range of 74-83%. Toxicologically relevant concentrations of the C(+/-)P(-)-isomers prevail almost twice as long after subcutaneous than after intravenous administration. From a toxicokinetic point of view, subcutaneous administration of C(+/-)P(+/-)-soman appears not to be a realistic model for the most relevant route of exposure to C(+/-)P(+/-)-soman in case of chemical warfare, i.e. short term respiratory exposure.

Research paper thumbnail of Effect of pretreatment with CBDP on the toxicokinetics of soman stereoisomers in rats and guinea pigs

Archives of Toxicology, 1993

Pretreatment of rats and guinea pigs with the specific carboxylesterase inhibitor 2-(o-cresyl)-4H... more Pretreatment of rats and guinea pigs with the specific carboxylesterase inhibitor 2-(o-cresyl)-4H-1:3:2-benzodioxaphosphorin-2-oxide (CBDP) reduces the LD50 of the nerve agent C(+/-)P(+/-)-soman in these species to the same range as in primates. This suggests that such CBDP-pretreated animals can be used in investigations that are relevant for prophylaxis and therapy of intoxication with C(+/-)P(+/-)-soman in primates including humans. In order to test this hypothesis we have studied the toxicokinetics of the toxic C(+/-)P(-)-isomers of soman in artificially respirated and CBDP-pretreated rats and guinea pigs at intravenous doses corresponding to 6x LD50. A comparison of the areas under the curve (AUCs) of the blood levels of C(+/-)P(-)-soman in pretreated and non-pretreated animals at the same absolute dose shows extreme nonlinearity with dose, indicating that CBDP occupies highly reactive binding sites which are no longer available for sequestration of the soman isomers. The AUCs of C(+/-)P(-)-soman at equitoxic doses of 6x LD50 are reduced by pretreatment with CBDP from 1683 to 464 ng.min.ml-1 in rats and from 978 to 176 ng.min.ml-1 in guinea pigs, which is in the range of the AUC in non-pretreated marmosets at an equitoxic dose (419 ng.min.ml-1). The blood levels of the C(+/-)P(-)-isomers in marmosets and CBDP rats are rather similar during the first 7 min, but persist in CBDP rats for 2 h longer at toxicologically relevant levels than in marmosets.(ABSTRACT TRUNCATED AT 250 WORDS)

Research paper thumbnail of Chemical and Biological Sensing IV (Proceedings Volume)

* Available as a photocopy reprint only. Allow two weeks reprinting time plus standard delivery t... more * Available as a photocopy reprint only. Allow two weeks reprinting time plus standard delivery time. No discounts or returns apply. ... Standard delivery in the US is 7 to 10 business days and outside the US delivery is 4 to 6 weeks or longer. For further details, please see shipping policy. ... Listed below are the papers found in this volume. Click the paper title to view an abstract or to order an individual paper. ... Sign up for monthly alerts of new titles released.