GC-CVAAS

Urine CVAA Solid phase microextraction headspace sampling, followed by GC/MS with El ionisation Deuterated CVAA Phenylarsine oxide LOD 500 ppt Short window for detection. Lack of validation in human samples. 

Blood CVAA (globin bound and free) GC-MS As above LOD InM As above... 

Figure 6.1 Bar-graph of MeHg in CRM 580. The results correspond to six replicate determinations as performed by different laboratories using various methods. MEANS indicates the mean of laboratory means with 95% confidence interval. Abbreviations-. CVAAS, cold vapour atomic absorption spectrometry CVAFS, cold vapour atomic fluorescence spectrometry ECD, electron capture detection GC, gas chromatography HPLC, high-performance liquid chromatography ICPMS, inductively coupled plasma mass spectrometry MIP, microwave induced plasma atomic emission spectrometry QFAAS, quartz furnace atomic absorption spectrometry SFE, supercritical fluid extraction.

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). 

Lewisite is too reactive to be analyzed by LC. Even with GC, it leads to a rapid degradation of column performance. Lewisites 1 and 2 initially hydrolyze to 2-chlorovinylarsonous acid (CVAA) (26) and bis(2-chlorovinyl)arsenous acid (28), respectively. LC/MS analysis of these trivalent acids is problematic, giving very poor signal-to-noise ratios in both... 

Jakubowski et al. (36) developed a GC/MS method for CVAA spiked into guinea pig urine using 1,2-ethanedithiol for derivatization, with phenyl arsine oxide as the internal standard. The same group later expanded the method to include atomic emission detection (AED) (37). CVAA was concentrated from urine (adjusted to pH 6 with 1M HC1) by SPE on Cl8. After elution with methanol and concentration to dryness, the residue was reconstituted and derivatized with ethanolic 1,2-ethanedithiol. Detection was by GC combined with arsenic selective AED and by electron impact/mass spectrometry (EI/MS) using SIM. Ions monitored were the moderately intense M+ ion at mlz 228, an intense ion [M — C2H4]+, mlz 200, and a base... 

The most sensitive method for CVAA has recently been reported by Wooten et al. (39) using solid-phase microextraction to concentrate the derivatized analyte. Urine, with added ammonium acetate buffer and PhAsO as an internal standard, was derivatized directly with 1,3-propanedithiol and the derivative concentrated on a poly(dimethylsiloxane) (PDMS) solid-phase microextraction (SPME) fiber. Analysis was by automated GC/MS using SIM of the isotopic MH+ ions. An impressive detection limit of 7.4pg/ml was reported, using a benchtop GC/MS system. The method was validated using spiked human urine. 

In 2002 extensive kinetic and product studies on the reactions of gaseous Hg with molecular and atomic halogens (X/X2 where X = Cl, Br) were performed at atmospheric pressure (750 1 Torr) and room temperature (298 1 K) in air and N2 [24]. Kinetics of fhe reactions with X/X2 were studied using both relative and absolute techniques. Cold vapour atomic absorption spectroscopy (CVAAS) and gas chromatography with mass spectroscopic detection (GC-MS) were the analytical methods applied. The measured rate constants for the reactions of Hg with CI2, Cl, Br2, and Br were (2.6 0.2) x IQ-i , (1.0 0.2) x 10" , < (0.9 0.2) x and (3.2 0.3) x 10 cm molecule s , respectively. Thus CI2 and Br2 are not important reactants in the troposphere for the CI2 and Br2 concentrations reported in literature [24]. 

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). 

The number of methods to verify an exposure to lewisite is limited. Chlorovinylarsonous acid (CVAA) can be found as the main metabolite in urine, while this compound can also be found as an adduct to hemoglobin (see Table 54.3). The analyte can be analyzed with GC-MS using normal configurations. 

Blood, urine, hair, fish (total, methyl Hg) Total digestion of sample with nitric, perchloric, and sulfuric acids Methyl mercury in hair digestion with HCI and extraction into benzene. Methyl mercury in blood, fish, and urine digestion with KOH and extraction into dithizone solution, cleaned up via extractions. Total CVAAS, methyl mercury GC/ECD 0.5 ng No data Akagi et al. 1995... 

Several other environmental matrices have been analyzed for mercury content. These include coal fly ash (Horvat and Lupsina 1991 Lexa and Stulik 1989), coal dust (Wankhade and Garg 1989), minerals (Bichler 1991), pesticides (Sharma and Singh 1989), gasoline (Costanzo and Barry 1988), and oily waste (Campbell and Kanert 1992). The methods used include CVAAS, DCASV, NAA, spectrophotometry, and GC/altemating current plasma detection (ACPD). The data on each method for each matrix were insufficient for making comparisons. 

Analytical Methods for Urine and Blood. Specific biomarkers of lewisite exposure are currently based on a very limited number of in vitro experiments (Jakubowski et al., 1993 Wooten et al., 2002) and animal studies (Logan et al., 1999 Fidder et al., 2000). Wooten et al. (2002) developed a solid-phase microextraction (SPME) headspace sampling method for urine samples followed by GC-MS analysis. It is the most sensitive method reported to date with a lower limit of detection of 7.4 pg/mL. Animal experiments have been limited in number and in their scope. In one study of four animals, guinea pigs were given a subcutaneous dose of lewisite (0.5 mg/kg). Urine samples were analyzed for CVAA using both GC-MS and GC coupled with an atomic emission spectrometer set for elemental arsenic (Logan et al., 1999). The excretion profile indicated a very rapid elimination of CVAA in the urine. The mean concentrations detected were 3.5 pg/mL, 250 ng/mL, and 50 ng/mL for the 0-8, 8-16, and 16-24 h samples, respectively. Trace level concentrations... 

CVAA is analyzed by GC-MS after derivatiza-tion (Figure 7) Like lewisite I, CVAA reacts readily with mono- and dithiols at ambient... 

Determination, offline GC-FlD samples are allowed to age (up to 42 days) and periodically extracted samples ageing leads to a recovery decrease due to a development as strong interactions between CVAA and matrix active sites, as time elapses comparison between three extraction methods. ... 

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