Thomas P. Logan

Detection and measurement of sulfur mustard offgassing from the weanling pig following exposure to saturated sulfur mustard vapor

Animal models are employed to investigate mechanisms of injury and to evaluate protective measures against sulfur mustard (HD) exposure. The ability to detect and quantify HD enables the researcher to follow safe procedures in handling skin samples. We designed an experimental procedure to measure HD offgassing from animal models. A Minicams®—a portable gas chromatograph equipped with a flame photometric detector and on‐line sorbent collection and desorption—was used to monitor the HD concentration. Confirming measurements were made using a two‐step process that trapped HD on a Tenax sorbent off‐line and then transferred the sample by means of an ACEM 900 to a gas chromato‐graph equipped with either a flame photometric detector or a mass spectrometer. Sulfur mustard offgassing data are presented from three experiments in which weanling pigs were exposed to saturated HD vapor via vapor caps containing 10 μl of HD. The HD concentration was measured in time‐weighted‐average (TWA) units at a specific HD application site. The current 8‐h maximum exposure limit for HD is 3‐ng l−1, (1 TWA unit). The largest TWA value measured near a 3 h time point was a Minicams measurement of 0.48 TWA at 2 h and 53 min after removal of a vapor cap containing HD from a single exposure site on an animal that had 24 concurrent dorsal exposure sites. Gas chromatography/flame photometric detection and gas chromatography/mass spectrometry were used to confirm the Minicams data and to provide greater sensitivity and selectivity down to 0.1 TWA. The gas hromatography/mass spectrometry data confirmed that HD concentrations fell below 0.1 TWA in <5 h for a specific site. These measurements of HD concentrations provided information on the expeditious and safe handling of HD‐exposed tissue. Published in 2000 by John Wiley & Sons, Ltd.

Cutaneous Uptake of 14C-Hd Vapor By The Hairless Guinea Pig

The hairless guinea pig (HGP) is used by our laboratory to model the human cutaneous response to sulfur mustard (HD), bis(2-chloroethylsulfide), exposure. We determined the HD content in the skin of HGP after a 7-min exposure to vapors saturated with a mixture of HD and 14C-HD. Concentration/time (CT) values in the range of 2 micrograms/cm2/min were determined by counting skin 14C disintegrations per min (dpm) in animals euthanized immediately after exposure. These values are similar to human penetration rates obtained by other investigators. A rate curve monitoring the reduction in skin 14C dpm was developed for animals euthanized between 0 and 24 hr post- exposure. This curve showed the greatest change after 1 hr. The epidermal (62%) to dermal (38%) ratio of 14C at 24 hr was measured for two animals. We saw no site preference for HD penetration among the 8 sites used. The 14C content of template adhesive tape was determined to follow HD distribution. These results contribute to a better understanding of the cutaneous response to HD in the HGP model.

Nuclear magnetic resonance analysis of the solution and solvolysis of sulfur mustard in deuterium oxide.

Our laboratory performs in vitro experiments in which cell cultures are exposed to sulfur mustard (HD) to investigate the toxicity of this agent of chemical warfare. To perform these experiments, it is important to know the rate of hydrolysis of HD in order to calculate the concentrations of HD and its hydrolysis products during the experiment. Researchers have previously investigated the kinetics and mechanism of the hydrolysis of HD using a variety of methods. In the present study, we used nuclear magnetic resonance (NMR) spectroscopy and gas chromatography/mass spectrometry (GC/MS) to investigate HDs dissolution and solvolysis in deuterium oxide (D 2 O) at 2 mM. We followed activity in proton spectrums and determined the half-life (t 1/2) of HD to be 7.0 ± 0.5 min in four experiments performed at 22°C. In addition, we determined the t 1/2 of HD in D 2 O containing 0.17 M sodium chloride to be 24 ± 1 min in three experiments performed at 22°C. As further proof of the existence of HD dissolved into D 2 O, deutero-hexane was used to extract the D 2 O HD solution. The resulting deutero-hexane solution was studied by 1 H NMR and GC/MS. The results obtained match those received from a standard deutero-hexane HD solution. These results demonstrate that HD can be identified in D 2 O with proton NMR and that proton NMR data can be used to monitor the subsequent solvolysis of HD.

A Method for the Analysis of Tabun in Multisol Using Gas Chromatographic Flame Photometric Detection

Preparation and analysis of tabun (GA) solutions are necessary for the continued development of countermeasures to this nerve agent. GA solutions must be stable and compatible for use in the test systems chosen for study; however, GA is very unstable in saline solutions. In the past we have found GA in saline at 2 mg/mL to be stable for a month or less at −70°C, whereas saline solutions of sarin (GB), soman (GD), and cyclosarin (GF) were stable for many months. Previous studies have shown that Multisol (48.5% H2O, 40% propylene glycol, 10% ethanol, and 1.5% benzyl alcohol) provides stable solutions of GA. We confirmed the stability of GA in Multisol with phosphorus nuclear magnetic resonance (P─NMR) and developed a method for the analysis of GA in Multisol using gas chromatographic flame photometric detection (GCFPD) in the phosphorus mode. The GC method used acetonitrile (CH3CN) for a dilution solvent because of its miscibility with GA in chloroform (CHCl3) standards and GA in Multisol samples at 1% (v/v). Furthermore, the dilutions with CH3CN made the phosphorus mode interference peak present in CHCl3 analytically manageable, reduced the interferences of Multisol in the GC separation, and contributed to a safe and reliable analysis of GA at 20 μg/mL. We demonstrated the stability of GA in Multisol stored for more than a year at 70°C. This method contributes a suitable technique for the preparation and analysis of reliable solutions of GA in nerve agent medical research and demonstrates the extended stability of GA in Multisol.

Application and detection of (14)c-hd in two mouse models.

The CD1-haired mouse and the SKH-hairless mouse are two animal models that have been used to evaluate sulfur mustard (HD) exposure and protection in our laboratory. In a recent study we observed that a substance P inhibitor protected the haired mouse ear against an HD solution, but the same drug was not successful in protecting the hairless mouse against HD vapor. This experiment prompted us to compare HD exposures between these models. We determined the 14C content in the skin after exposures to HD containing 14C-HD. Rate curves were generated for applications of (1) HD in methylene chloride to the haired mouse ear; (2) HD in methylene chloride to the hairless mouse dorsal skin; and (3) saturated HD vapor to the hairless mouse dorsal skin for 6 min. The curves showed a reduction in 14C disintegrations per min in animals euthanized 0 to 2 h postexposure. The largest percentage of decrease of 14C content in skin occurred within 30 min of HD challenge for all exposures. An 8-mm skin-punch biopsy and a 14-mm annular skin section surrounding the region of the 8-mm skin punch were taken from the hairless mouse dorsal skin exposed to HD in methylene chloride. The ratio of the 14C content in the 8-mm skin punch to that in the surrounding 14-mm annular skin section was 7.3, demonstrating that the HD application spreads beyond the initially biopsied site. A concentration/time value of 6.3 μg/cm2/min was determined by counting skin 14C disintegrations per minute in animals euthanized immediately after exposure to saturated HD vapor. Determinations of the amount of HD showed that similar quantities of HD, 0.4 mg, were detected on each model. These results contribute to a better quantitative understanding of HD application in the haired and hairless mouse models.

An Investigation into the Stability of Sulfur Mustard and Soman in Perfluorooctylbromide

ABSTRACT Perfluorooctylbromide (PFOB) was investigated as a potential stabilizer of sulfur mustard (HD) and soman (GD) because of its physical-chemical properties and its low toxicity. Separately, HD and GD solutions in PFOB were tested from −70°C to 50°C by using nuclear magnetic resonance (NMR) and were found to be stable. When mixed with 10% (v/v) H2O, the HD/PFOB sample decomposed (t1/2 = 37 hours at 22°C), whereas the GD/PFOB sample remained unchanged for more than 24 hours. For additional identification before H2O addition, the compounds were extracted from PFOB with acetonitrile and analyzed by using gas chromatography mass spectrometry (GCMS), and HD and GD were readily identified in their respective samples. We demonstrated by NMR and GCMS that PFOB solutions of HD and GD maintained their stability over a wide range of temperatures. We demonstrated by NMR that PFOB extended the stability of HD and GD when exposed to H2O. These results prompt us to offer PFOB as a potential candidate for sample collection, preservation, and forensic analysis of HD and GD evidence and as a preservative vehicle for research on tissue exposed to chemical warfare agents.