Lewisite detection

The recent development and comparative application of modern separation techniques with regard to determination of alkylphosphonic acids and lewisite derivatives have been demonstrated. This report highlights advantages and shortcomings of GC equipped with mass spectrometry detector and HPLC as well as CE with UV-Vis detector. The comparison was made from the sampling point of view and separation/detection ability. The derivatization procedure for GC of main degradation products of nerve agents to determine in water samples was applied. Direct determination of lewisite derivatives by HPLC-UV was shown. Also optimization of indirect determination of alkylphosphonic acids in CE-UV was developed. Finally, the new instrumental development and future trends will be discussed. 

Thioether. Mustard agent received its name because of garlic, horseradish, or mustard odor that can be detected by smell. The human nose can detect mustard (H, HD) in concentrations of 0.6 to 1.0 mg/m3. It must be understood that until recently, the U.S. military had no automatic vapor/liquid detection capability. Therefore, alert soldiers would most likely smell the agent vapor before encountering the liquid (after release, H or HD appears as a thick, colorless or pale yellow liquid HL, or mustard/lewisite mixture, appears as a dark oily cloud that can be detected visually). 

Automatic Liquid Agent Detector (ALAD) A liquid agent devise that can detect droplets of GD, VX, HD. and Lewisite as well as thickened agents. It transmits its alarm by field wire to a central alarm unit. 

Arsenic Toxicosis. Urine arsenic is the best indicator of current or recent exposure. Atomic absorption spectrophotometry is preferred as the detection method. Hair or fingernail sampling may also be helpful. Use of blood is useful if analyzed soon after exposure or in cases of continuous chronic exposure. After acute exposure, chelation therapy is instituted utilizing either (1) Dimercaprol BAL (British Anti-Lewisite) and analogues ... 

FOX vehicle detects vapours of Lewisite blister agent. HQ responds that detection was a false alarm, caused by oil smoke. FOX vehicle separates petroleum peaks from the agent spectrum and confirms detection. 1st Marine Division Log states Ripper 6 believes that chemical weapons were used, but not sure if Ripper was the target. These chemical munitions could have been exploded by our own artillery, thus causing secondary explosions ... 

FOX team observes artillery attack to north-west at distance of about 4 km. About 5 minutes later, the mass spectrometer on the FOX vehicle sounds an alarm. The agent detected is Lewisite in a concentration to produce casualties but not death... 

B.A. Tomkins, G.A. Sega and C.-H. Ho, Determination of Lewisite oxide in soil using solid-phase microextraction followed by gas chromatography with flame photometric or mass spectrometric detection, J. Chromatogr., A, 909, 13-28 (2001). 

The reaction product of arsenic trichloride (see Table 1) with 3,4-dimercaptotoluene, 2-chloro-5-methyl-l,3,2-benzodithiarsole, still contains an active chlorine atom, rendering its determination by GC/MS difficult. The derivatization reaction can also be carried out with 2-chlorovinylarsenic oxide (lewisite oxide, CAS 3088-37-7), which is one of the degradation products of lewisite 1. Thus, the highly reactive arsenous compounds can be detected as less reactive derivatives amenable to GC/MS. 

Procedures based on GC/MS for the determination of the lewisite 1 decomposition product 2-chlorovinylarsonous acid (CVAA, CAS number 85090-33-1) in urine and blood have also been developed. In one procedure, CVAA is converted with BAL the resulting CVAA/BAL product isolated by SPE on a C18-cartridge and further derivatized with heptafluorobutyryl imidazole (51). A later developed procedure is based on the derivatization of CVAA with 1,3-propanedithiol followed by SPME isolation and GC/MS analysis. Using SIM at the molecular ion peaks, the limit of detection was determined at 7.4 pg per ml urine (52). 

Little information is available regarding the toxieokineties of lewisite. Lewisite is readily absorbed by mueous membranes and, beeause of its lipophilicity, dermal absorption is signitieant (HSDB, 2004). Dermal absorption is reportedly more rapid than for sulfur mustard (Hurst and Smith, 2008). Axehod and Hamilton (1947) reported that radiolabeled ( " As) lewisite applied to a 0.4S em area of human skin was primarily fixed on the epidermis and that very little was found in the dermis most was detected in hair and hair follicles. In experiments with guinea pigs, histological examination revealed that lewisite applied to skin entered epidermis within 2 min and penetrated into the dermis within 10 min (Ferguson and Silver, 1947). Only trace amounts were detectable in the dermis at 24 h post-application. 

Bowden, E. (1943). Median detectable concentrations by odor of plant run mustard, plant run Lewisite and pilot plant ethyl nitrogen mustard. ADB 969801, TDMR 615 (April). 

Lewisite is reported to possess a characteristic (geraniumlike) odor in the range of 0.8 mg/m to more commonly cited 14-23 mg/m median detection (Pechura and Rail, 1993). US forces have detectors for lewisite-paper and kits (M7 and M9A). Other forensic techniques for soil and material analysis already exists (e.g. gas chromatography). In biological tissues, increased arsenic levels are a surrogate for lewisite (Haddad and Wincester, 1983). 

Once incorporated, unbound lewisite is quickly hydrolyzed. Its predominant metabolite is 2-chlorovinylarsonous acid, CVAA (Figure 50.8). Analytical methods to confinn lewisite exposure have, at least in the past, focused on the detection and quantification of CVAA. However, Noort et al. (2002) also pointed out that due to the high affinity of arsenic towards sulfhydryl groups, adducts of lewisite/ CVAA and cysteine residues of proteins are formed. In an in vitro study, incubating " C-labeled lewisite with human blood samples, 90% of lewisite was found in erythrocytes, whereas 25 to 50% of arsenic was bound to globin. From these protein adducts, CVAA can be released to form an adduct with the antidote British Anti-Lewisite (BAL) (Fidder et al, 2000). The authors were also able to identify a specific protein adduct of lewisite formed with the cysteine residues 93 and 112 of P-globin. See Detection of DNA and protein adducts of vesicants, below, for analytical... 

In vivo, unbound CVAA is quickly excreted via the renal pathway and cannot be detected in urine samples taken later than 12 h post-exposure. However, the biological half-life of protein adducts is much longer in blood samples taken 10 days post-exposure and treated with BAL, Fidder et al. (2000) were still able to release 10% of the CVAA-BAL concentration found on day 1. Thus, protein adducts of CVAA have an important role in the verification of potential lewisite exposure. 

Incubation of lewisite-protein adducts with BAL is capable of transferring its metabolite 2-chlorovinylarsonous acid (CVAA) into a BAL-CVAA derivative. This derivative can be quantified using GC-MS. The method is able to detect a 1 nM lewisite exposure of human blood in vitro (Fidder et al, 2000). 

Nasal irritation by lewisite begins at 8 mg min m and its odor is detected at 20mgminm . Vesication and death from lewisite inhalation is caused at the same Ct as mustard, which is 1500mgminm . The immediately dangerous to life health (IDLH) value of lewisite is 0.003 mg m . Lewisite causes vesication at 14 mg and the LD50 is 2.8 g on the skin. 

Liquids Lewisite can be detected by M8 paper and all Arsenical Vesicants can be detected by M9 paper. 

Lewisite (L). Colorimetric tubes are available which can detect organic arsenic compounds as well as arsine. Detection with PIDs or FIDs may be possible. Detection and identification with FT-IR is possible provided that the appropriate reference spectra are available. 

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