Organoarsenicals sampling

Similarly, in 0.1 M hydrochloric acid or at pH 5.3 resolution from the wave of triphenylarsine oxide is not possible. At pH > 7 only the latter species is active. Thus, by choice of a suitable pH, specific determination of phenylarsonic acid, diphenylarsinic acid and triphenylarsineoxide in mixtures is possible. Inorganic arsenic(V) is electroinactive while the tetraphenylarsonium ion is reduced at much more negative potentials. Arsenic(III) species are reduced at more positive potentials. Polarography is thus of value for the quantitative speciation of organoarsenic samples. 

An inductively coupled plasma formed by passing argon through a quartz torch is widely used for the mass spectroscopic analysis of metal compounds separated by online HPLC.6 Samples are nebulized on introduction into the interface. Plasma impact evaporates solvent, and atomizes and ionizes the analyte. Applications include separation of organoarsenic compounds on ion-pairing F4PLC and vanadium species on cation exchange. 

Accurate estimates of worker exposure to organoarsenicals have not been possible because l) extensive studies of collection media for sampling organoarsenicals in air have not been performed and... 

Analytical Procedure. The optimized analytical procedure for determination of organoarsenicals on the collected filter samples is as follows. 

The organoarsenical particulates are extracted ultrasonically from the filters for 30 minutes in 25 mL of an aqueous carbonate/ bicarbonate/borate buffer (Eluent 1, Table I). After sonication the resulting extracts are ready for analysis and no further sample preparation is necessary. 

Table I. Instrumental conditions for the analysis of organoarsenicals in air particulate samples...

Three filtering media commercially available from Millipore Corporation were evaluated for the collection of airborne particulates of the organoarsenical compounds. These were (l) cellulose ester membranes (2) Fluoropore and (3) Mitex. The cellulose ester membrane filters (0.8 ym pore size) are the standard Millipore filters used for aerosol sampling and consist of a mixture of cellulose nitrate and cellulose acetate. The Fluoropore filters are made of Teflon (PTFE) and are bonded to a polyethylene net. Fluoropore filters with a pore size of 1.0 ym were selected for this study. 

Organoarsenical Species Filter Stage Control Samples Samples Exposed to 1 ppm S0o ... 

The diagnosis of chronic arsenic poisoning involves integration of the clinical findings with confirmation of exposure. Urinary levels of total arsenic, usually less than 50 g/24 h, may return to normal within days to weeks after exposure ceases. Because it may contain large amounts of nontoxic organoarsenic, all seafood should be avoided for at least 3 days prior to submission of a urine sample for diagnostic purposes. The arsenic content of hair and nails (normally less than 1 ppm) may sometimes reveal past elevated exposure, but results should be interpreted cautiously in view of the potential for external contamination. 

Urine samples Arsenic Ten organoarsenic compounds Microbore HPLC, ES-MS-MS 2-21 pg As (positive ion mode) Pergantis et al. (1997)... 

The detection limits of a pulsed flame photometric detector (PFPD) are much better than those of any conventional FPD, and in addition the detector does not suffer the quenching of co-eluting hydrocarbon chemicals (45). The ability to also detect arsenic or nitrogen containing chemicals makes the PFPD very useful for the screening of CWC-chemicals. Frishman and Amiraw (46) used fast GC equipped with a short capillary column (1.5 m) and PFPD for the analysis of air samples. A complete analysis cycle time of 30 s was demonstrated. Killelea and Aldstadt (47) used PFPD in the arsenic selective mode for the analysis of organoarsenic chemicals. 

J. J. Sloth, E. H. Larsen, K. Julshamn, Determination of organoarsenic species in marine samples using gradient elution cation exchange HPLC-ICP-MS, J. Anal. Atom. Spectrom., 18 (2003), 452-459. 

Ringmann, S., Boch, K., Marquardt, W., Schuster, M., Schlemmer, G., Kainrath, P. Microwave-assisted digestion of organoarsenic compounds for the determination of total arsenic in aqueous, biological, and sediment samples using flow injection hydride generation electrothermal atomic absorption spectrometry. Anal. Chim. Acta 452, 207-215 (2002)... 

Most of the classical procedures for decomposing organoarsenic compounds present in samples prior to the determination of total inorganic arsenic incorporate some mode of wet or dry digestion to destroy the organically bound arsenic, in addition to all other organic constituents present in the sample. 

The percentage recoveries obtained by the digestion procedure with AgDDC analysis and atomic absorption analysis are given in Table 8. Results obtained by this digestion method applied to the aeration feed (AF) and settling basis effluent (SBE) samples spiked with each of the three organoarsenicals equivalent to 5 ng or arsenic are presented in Table 9. 

Talmi and Bostick and Talmi and Norvell improved the method by using gas chromatography. Although the method is highly sensitive, it has some disadvantages. It cannot discriminate all arsenic compounds in the biological samples because the same arsines can be produced by reduction from different organoarsenicals. Furthermore, the collection efficiency is incomplete for the very volatile arsine (b.p. — 55°C), and two reduction steps are necessary to discriminate between As(III) and As(V). 

Four organoarsenic species 56-59 have been isolated from Laminaria sp. [132], Compound 64 and two diastereoisomers 65 and 66 were found as major compounds [133]. Arsenic-containing ribofuranosides 56-59 as well as inorganic compounds have been isolated from freshly collected samples of the Australian brown kelp Ecklonia radiana [134]. 

The concentrations of the three arsenicals (75-77) were determined in 37 marine organisms comprising algae, crustaceans, bivalves, fish and mammals by high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICPMS) [170]. All three organoarsenics, which occurred at pg/kg concentrations, were detected in 25, 23 and 17 of the 37 samples analyzed, respectively. The limits of detection were 2-3 pg/kg dry mass. The data illustrate that all three compounds are common minor constituents in practically all marine samples. 

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