Digestion methods for analysis of fly ash samples by atomic absorption spectrometry

ENEA CRE Casaccia AMB/TEIN/CHIM, Via Anguillarese 301, 00060 Rome, Italy
Analytica Chimica Acta (Impact Factor: 4.52). 08/1999; 395(1-2):157-163. DOI: 10.1016/S0003-2670(99)00342-6

ABSTRACT The efficiency of different digestion methods (six microwave decomposition methods and a wet acid digestion method) in the solubilisation of six metals (Cr, Ni, Cu, Pb, Cd, Zn), for their determination in fly ashes, was compared. Five different mineral acid mixtures and two different microwave systems were tested. The study was carried out by analyzing two highly homogenised fly ash samples (from sewage sludge and city waste incineration) provided by the Joint Research Centre of Ispra. Determinations were performed by atomic absorption spectrometry and by inductively coupled plasma atomic emission spectrometry. The analytical performance of the laboratory was evaluated using the 1633a Coal Fly Ash Standard Reference Material of National Bureau of Standards (NBS SRM 1633a).Results showed that a HNO3 microwave treatment was strong enough to solubilise metals from the considered fly ashes. Moreover, microwave methods generally provided higher release than the classical aqua regia method, whereas no significant advantage was observed using a high performance microwave unit.

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    ABSTRACT: The objective of this paper was to evaluate the efficiency of the five different combinations of solvent used in the classical wet digestion procedure for the determination of Fe, Pb and Zn contents in canned sardine. The different solvent combinations evaluated were HNO3, HNO3: HCl (1:1), HNO3: HCl (1:2), HNO3: HCl (1:3) and HNO3 : H2SO4 (1:1). The combination with the most reliable performance recovery was employed to study the level of Pb, Fe and Zn in canned sardines manufactured from different countries and with different shelf lives. Results indicated that this combination, HNO3: HCl (1:2), produced the most satisfactory percentage recovery. The content of Fe, Pb and Zn in the canned sardines were found to be below the permitted level established in the Food Act 1983 and Food Regulation 1996. However, leaching of Fe and Pb from the can was likely to have occurred in products stored for a longer period of time. This was evidenced by the determination of metal contents in the gravy from the canned sardines. Nevertheless, leaching of Zn was not observed.
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    ABSTRACT: Four classical wet digestion procedures for the determination of mercury (Hg) by cold-vapour atomic absorption spectrometry in fish tissue were investigated with the aim of selecting and optimising the most convenient and inexpensive for use in a low technology environment. A mixture of H2O, HNO3, HClO4 and H2SO4 or a mixture of HCl, HNO3, HClO4 and H2SO4 was used for the digestion in two different vessels namely thick walled long neck 50ml volumetric flask and 50ml 26mm×200mm pyrex test tube. The effect of temperature and time on the digestion efficiency of the mixture of HCl, HNO3, HClO4 and H2SO4 using test tubes were investigated to obtain the optimum conditions. Mercury was partly lost at temperatures above 230°C and this was pronounced when decomposition time was more than 30min. Detection limit for the optimised procedure was 0.52ngg−1. The optimised procedure was employed to study the level of Hg in canned fish samples. Concentration of Hg in the samples tested ranged from 0.015 to 0.139μgg−1 wet weight.
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    ABSTRACT: A method based on flow injection-isotope dilution-cold vapor-inductively coupled plasma mass spectrometry (FI-IDCV-ICP/MS) has been applied to determine trace level of mercury in fly ash. isotopic spike was added to 0.25 g of BCR176R fly ash and then decomposed by microwave digestion procedure with acid mixture A (8 mL + 2 mL HCl + 2 mL HF) and acid mixture B (8 mL + 2 mL + 2 mL HF) for applying IDMS. Mercury cold vapor was generated by using reductant solution of 0.2% (w/w) and 0.05% (w/w) NaOH. The measurements of n()/n() isotope ratio was made using a quadrupole ICP/MS system. The accuracy in this method was verified by the analysis of certified reference material (CRM) of fly ash (BCR 176R). The indicative value of Hg in BCR 176R fly ash was mg/kg (k = 2). The determined values of Hg in BCR 176R fly ash by the method of FI-CV-ID-ICP/MS described in this paper were mg/kg (k = 3.18) and the analysis results were in well agreement with the indicative value within the range of uncertainty.
    Mass Spectrometry Letters. 06/2012; 3(2).


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