Cold vapor generation

Atomic absorption spectroscopy is more suited to samples where the number of metals is small, because it is essentially a single-element technique. The conventional air—acetylene flame is used for most metals however, elements that form refractory compounds, eg, Al, Si, V, etc, require the hotter nitrous oxide—acetylene flame. The use of a graphite furnace provides detection limits much lower than either of the flames. A cold-vapor-generation technique combined with atomic absorption is considered the most suitable method for mercury analysis (34). 

No preconcentration or isolation/separation procedures applied Physico-chemical separation/preconcentration Hydride generation, cold vapor generation (Hg)... 

J. Moreda-Pineiro, P. Fopez-Mahia, S. Muniategui-Forenzo, E. Fernandez-Fernandez and D. Prada-Rodriguez, Direct mercury determination in aqueous slurries of environmental and biological samples by cold vapor generation-electrothermal atomic absorption spectrometry. Anal. Chim. Acta, 460(1), 2002, 111-122. 

S. E. Long and W. R. Kelly, Determination of Mercury in Coal by Isotope Dilution Cold-Vapor Generation Inductively Coupled Plasma Mass Spectrometry, Anal. Chem. 2002, 74, 1477. 

Qiang, T., W. Johnson, and B. Buckley. 2003. Mercury speciation analysis in soil samples by ion chromatography, post-column cold vapor generation and inductively coupled plasma mass spectrometry. J. Anal. At. Spectrom. 18 696-701. 

Total mercury, inorganic mercury, and methylmercury in water were determined using a simple and ultrasensitive method, based on cold vapor generation (CVG), coupled to atomic fluorescence... 

Gil, S., I. Lavilla, and C. Bendicho. 2006. Ultrasound-promoted cold vapor generation in the presence of formic acid for determination of mercury by atomic absorption spectrometry. Anal. Chem. 78 6260-6264. 

A combination of IPC and inductively coupled plasma (ICP) MS was extensively explored for the speciation of phosphorus, arsenic, selenium, cadmium, mercury, and chromium compounds [108-118] because it provides specific and sensitive element detection. Selenium IPC speciation was joined to atomic fluorescent spectrometry via an interface in which all selenium species were reduced by thiourea before conventional hydride generation [119], Coupling IPC separation of monomethyl and mercuric Hg in biotic samples by formation of their thiourea complexes with cold vapor generation and atomic fluorescence detection was successfully validated [120]. The coupling of IPC with atomic absorption spectrometry was also used for online speciation of Cr(III) and Cr(VI) [121] and arsenic compounds employing hydride generation [122]. 

IPC separation of monomethyl and mercuric Hg in biotic samples by formation of their thiourea complexes, coupled to cold vapor generation and atomic fluorescence detection, was successfully validated [18]. The coupling of IPC with atomic absorption spectrometry was also used for online speciation of arsenic compounds employing hydride generation [17]. In the analytical speciation of chromium using in... 

Long, S.E., Kelly, W.R. Determination of mercury in coal by isotope dilution cold-vapor generation inductively coupled plasma mass spectrometry. Anal. Chem. 74, 1477-1483 (2002)... 

Methods have been developed for the determination of mercury in fish, shellfish, foods, food sources, and pharmaceuticals. AAS, usually with cold vapor generation (CVAAS), is one of the primary methods used to measure mercury in these complex matrices (Carrillo et al. 1986 Friese et al. 1990 Landi et al. 1990 ... 

The use of cold vapor generation coupled to ICP-MS lowers the detection limit by about a factor of 15, facilitating the detection of mercury species in ocean water samples,which is not possible with conventional nebulization. The use of cold vapor AAS allows for the detection of mercury compounds down to between 0.1 and 1 ng for Hg (II), methyl mercury, and ethyl mercury (depending on the system). 

Analyte Separation/Concentration Enrichment, separation, isolation, concentration, matrix or compound separation, physico-chemical separation, hydride generation, cold vapor generation (Hg), solvent extraction (complexation), precipitation/coprecipitation, chromatography (including extraction, ion exchange, adsorption), distillation, volatilization, electrolysis, electrodeposition... 

The 71-page chapter by Ihnat (1982) on Application of Atomic Absorption Spectrometry to the Analysis of Foodstuffs, adheres strictly to the goal set out by editor Cantle of providing readers with a methods compendium. It concentrates on detailed recommended procedures for various food commodities, extracted from official , recommended and other sources judged reliable by the author, for the preparation (pretreatment and treatment, e.g., decomposition) of analytical samples and standards, and the determination of 21 elements by FAAS, including hydride and cold vapor generation techniques. Price and Whiteside... 

CSV cathodic stripping voltammetry CVAAS cold vapor generation atomic absorption spectrometry (specific for Hg) CVAFS cold vapor atomic fluorescence spectrometry... 

Suddendorf, R.F. (1981) Interference by selenium and tellurium in the determination of mercury by cold vapor generation atomic absorption spectrometry. Anal. Chem., 53, 2234-2236. 

Tanabe, K., Takahashi, J., Haraguchi, H., and Fuwa, K. (1980) Vacuum-ultraviolet atomic absorption spectrometry of mercury with cold vapor generation. Anal. Chem., 52, 453-457. 

A Varian 475 spectrophotometer and M-65 vapor generation accessory is used for the determination of mercury through cold vapor generation and for the determination of As, Se Sb, Bi ... 

Atomic Absorption Spectrometry (AAS) and Atomic Emission Spectrometry (AES) 451 Cold vapor generation technique... 

Fig. 12.12 Scheme of a cold vapor generation system for mercury (redrawn from [17]). 

The elemental Hg is subsequently purged and swept out of the sample. Figure 3.40 illustrates what accessories are needed to prepare a sample for direct introduction of elemental mercury vapor into a flow-through atomic absorption cell. This modification to the atomic absorption spectrophotometer is called a cold vapor generator. 

Hydride generation techniques are superior to direct solution analysis in several ways. However, the attraction offered by enhanced detection limits is offset by the relatively few elements to which the technique can be applied, potential interferences, as well as limitations imposed on the sample preparation procedures in that strict adherence to valence states and chemical form must be maintained. Cold-vapor generation of mercury currently provides the most desirable means of quantitation of this element, although detection limits lower than AAS can be achieved when it is coupled to other means of detection (e.g., nondispersive atomic fluorescence or micro-wave induced plasma atomic emission spectrometry). 

High -precision measurement of mercury isotope ratios in sediments using cold vapor generation multicollector inductively coupled plasma mass spectrometry. Anal. Bioanal. Chem., 384, 1470-1478. 

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