Cold vapour atomic absorption

Mercury vapour in air Diffusive samplers with qualitative onsite colorimetric analysis and quantitative cold vapour atomic absorption spectrometry in the laboratory 59... 

MDHS 14 General method for the gravimetric determination of respirable and total dust MDHS 15 Carbon disulphide MDHS 16 Mercury vapour in air Laboratory method using hopcalite adsorbent tubes, and acid dissolution with cold vapour atomic absorption spectrometric analysis MDHS 17 Benzene in air Laboratory method using charcoal adsorbent tubes, solvent desorption and gas chromatography MDHS 18 Tetra alkyl lead compounds in air Continuous on-site monitoring method using PAC Check atomic absorption spirometry... 

Mercury was determined after suitable digestion by the cold vapour atomic absorption method [40]. Lead was determined after digestion by a stable isotope dilution technique [41-43]. Copper, lead, cadmium, nickel, and cobalt were determined by differential pulse polarography following concentration by Chelex 100 ion-exchange resin [44,45], and also by the Freon TF extraction technique [46]. Manganese was determined by flameless atomic absorption spectrometry (FAA). 

The following analytical techniques seem to be adequate for the concentrations under consideration copper and nickel by Freon extraction and FAA cold vapour atomic absorption spectrometry, cobalt by Chelex extraction and differential pulse polarography, mercury by cold vapour atomic absorption absorptiometry, lead by isotope dilution plus clean room manipulation and mass spectrometry. These techniques may be used to detect changes in the above elements for storage tests Cu at 8 nmol/kg, Ni at 5 nmol/kg, Co at 0.5 nmol/kg, Hg at 0.1 nmol/kg, and Pb at 0.7 nmol/kg. 

Reduction to metallic mercury was used by an overwhelming proportion of the participants, with stannous chloride as reductant in all but one case in which sodium borohydride was used. In all cases but four, the participants used cold-vapour atomic absorption for final determination. This makes comparison of detection techniques difficult, but the good results ob-... 

Agemian and Chau [55] have described an automated method for the determination of total dissolved mercury in fresh and saline waters by ultraviolet digestion and cold vapour atomic absorption spectroscopy. A flow-through ultraviolet digester is used to carry out photo-oxidation in the automated cold vapour atomic absorption spectrometric system. This removes the chloride interference. Work was carried out to check the ability of the technique to degrade seven particular organomercury compounds. The precision of the method at levels of 0.07 pg/1, 0.28 pg/1, and 0.55 pg/1 Hg was 6.0%, 3.8%, and 1.00%, respectively. The detection limit of the system is 0.02 pg/1. 

Methylmercury has been preconcentrated from seawater by extraction with a solution of dithizone prior to analysis by gold foil cold vapour atomic absorption spectrometry [126]. 

Langmyhr et al. [45] have applied cold vapour atomic absorption spectrometry to the determination of organomercury compounds in soils and sediments. 

G. A. Zachariadis and J. A. Stratis, Optimisation of cold vapour atomic absorption spectrometric determination of mercury with and without amalgamation by subsequent use of complete and fractional factorial designs with univariate and modified simplex methods, J. Anal. At. Speetrom., 6(3), 1991, 239-245. 

Methods based on acid digestions of the soil with 7 M nitric acid [ 136] or sulfuric acid-nitric acid [137] have been described. Released mercury is absorbed in stannous chloride-sulfuric acid-hydroxylamine [ 136] or potassium permanganate-potassium persulfate-hydroxylamine-sodium chloride [137] prior to cold vapour atomic absorption spectrometry. 

Kuwae et al. [138] have described a rapid determination of mercury in soils by high-frequency induction heating (rf) followed by cold vapour atomic absorption spectrometry. The mercury released from the sample is absorbed in stannous chloride-hydroxylamine prior to atomic absorption spectrometry. Recovery of 99.4 to 99.8% mercury was obtained by this method from portions of sample containing between 0.025-0.15 p,g of mercury. 

Nicolson [139] has described a rapid thermal decomposition technique for the atomic absorption determination of mercury in soils. In this method, air is used to sweep mercury vapour from the heated (650-750 °C) sample onto gold foil. In the second stage, heating of the gold foil releases mercury vapour into a cold vapour atomic absorption spectrometer. 

Cold vapour atomic absorption spectrometry and atomic fluorescence spectrometry (253 nm emission) have been applied to the determination of down to 0.01 mg/kg of mercury in soils and sediments [ 144],... 

Sakamoto et al. [148] have shown that the differential determinations of different forms of mercury in soil can be accomplished by successive extraction and cold vapour atomic absorption spectrometry. 

Bandyopadhyay and Das [151] extracted mercury from soils with the liquid anion exchanger Aliquat-336 prior to determination by cold vapour atomic absorption spectrometry. 

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.

Tsalev, D.L., M. Sperling, and B. Welz. 1992,On-line microwave sample pre-treatment for hydride generation and cold vapour atomic absorption spectrometry. Part 2. Chemistry and applications. Analyst 117 1735-1741. 

Welz, B., D.L. Tsalev, and M. Sperling. 1992. On-line microwave sample pretreatment for the determination of mercury in water and urine by flow-injection cold-vapour atomic absorption spectrometry. Anal. Chim. Acta 261 91-103. 

Munaf, E., H. Haraguchi, D. Ishii, T. Takeuchi, and M. Goto. 1990. Speciation of mercury compounds in waste water by microcolumn liquid chromatography using a preconcentration column with cold-vapour atomic absorption spectrometric detection. Anal. Chim. Acta 235 399 404. 

On-line preconcentration followed by liquid chromatographic separation and cold vapour atomic absorption spectrometry have been used to detect 0.5ppt methylmercuiy in non saline water [43],... 

B. Welz, M. Melcher, Decomposition of marine biological tissues for determination of arsenic, selenium and mercury using hydride-generation and cold vapour atomic absorption spectrometeries, Anal. Chem., 57 (1985), 427-431. 

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]. 

An example is the determination of mercury in foodstuffs using cold vapour atomic absorption spectroscopy. The organic matter in foodstuffs is destroyed by wet oxidation. The mercury in solution is then reduced to the metallic state and released as a vapour in a stream of air. The quantity of mercury vapour in the air stream is measured by cold vapour atomic absorption spectroscopy. This part off the method is called the end determination. Often, as in this example, the end determination is equivalent to the analytical technique for the method. 

Maintaining the quality of food is a far more complex problem than the quality assurance of non-food products. Analytical methods are an indispensable monitoring tool for controlling levels of substances essential for health and also of toxic substances, including heavy metals. The usual techniques for detecting elements in food are flame atomic absorption spectroscopy (FAAS), graphite furnace atomic absorption spectrometry (GF AAS), hydride generation atomic absorption spectrometry (HG AAS), cold vapour atomic absorption spectrometry (CV AAS), inductively coupled plasma atomic emission spectrometry (ICP AES), inductively coupled plasma mass spectrometry (ICP MS) and neutron activation analysis (NAA). 

Cold Vapour Atomic Absorption Spectrometry CV AAS is the best and most sensitive method for determining very low levels of mercury it makes use of the fact that atoms of this element can exist in gaseous form at room temperature. 

Ahmed, R., Stoeppler, M. Decomposition and stability studies of methylmercury in water using cold vapour atomic absorption spectrometry. Analyst 111, 1371-1374 (1986)... 

DETERMINATION OF MERCURY IN ENVIRONMENTAL WATER SAMPLES BY REDUCnON-AERATION/AMALGAMATION AND COLD VAPOUR ATOMIC ABSORPTION SPECTROMETRY (CVAAS)... 

A modified reduction-aeration method to analyse mercury in environmental water samples is described. After aeration of the sample, the mercury is pre-concentrated on gold-coated sand which is then analysed by thermal desorption and cold vapour atomic absorption spectrometry (CVAAS). When applying reduction-cells of volumes up to 1 1, limits of detection as low as 1 ng.r are obtained. The method avoids matrix-effects caused by complexing agents such as Cl and 1, which interfere in the direct measurement of mercury by common CVAAS-techniques. The method was applied to dty drinking-water. Mercury levels ranging from less than 1 ng.l" to 10 ng.T were found. 

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