Rapid food decomposition by H2O2-H2SO4 for determination of total mercury by flow injection cold vapor atomic absorption spectrometry.
A mixture of 50% H2O2-H2SO4 (3 + 1, v/v) was used for decomposition of food in open vessels at 80 degrees C. The treatment allowed rapid total mercury determination by flow injection cold vapor atomic absorption spectrometry. Cabbage, potatoes, peanuts paste, hazelnuts paste, oats, tomatoes and their derivatives, oysters, shrimps, prawns, shellfish, marine algae, and many kinds of fish were analyzed by the proposed methodology with a limit of quantitation of 0.86 +/- 0.08 microg/L mercury in the final solution. Reference materials tested also gave excellent recovery.
Determinação dos teores de Hg, Pb, Cd, Cu e Zn em moluscos (Crassostrea brasiliana, Perna perna e Mytella falcata) Determination of Pb, Cd, Hg, Cu and Zn levels in molluscs (Crassostrea brasiliana, Perna perna and Mytella falcata)
. Bivalves as filter-feeders and bioaccumulators of chemical and biological residues can offer risk to public health when consumed by the population. This study aims at determining Pb, Cd, Hg, Cu and Zn levels in bivalves C. brasiliana, P. perna and Mytella falcata collected in several natural sandbanks in the coastal Baixada Santista, São Paulo. Seventy samples from twelve natural sandbanks were collected and analyzed from September 1996 to February 1997. Mercury concentration in soft tissues of bivalves was determined by continuos flow injection – flameless atomic absorption spectrometry. Pb, Cd, Zn and Cu were determined by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES). The results showed that Pb, Cd, Hg and Cu levels in samples were according to Brazilian legislation. The concentration of Zn for all samples of oyster C. brasiliana was higher than those indicated by legal limits for foods in Brazil, that is 50 mg/kg; for other samples the Zn levels were below the levels established for Brazilian legislation.
Critical comparison of two standard digestion procedures for the determination of total mercury in natural water samples by cold vapour atomic absorption spectrometry
Abstract Two pretreatment procedures for total mercury determinations in natural water samples were compared. The first, the Swedish Standard method (DP1), involves digestion of water in the presence of concentrated nitric acid at 120°C and under pressure for 30 min. In the West German Standard method (DP2), small volumes of nitric and sulphuric acids, permanganate and peroxodisulphate are added to the sample, and digestion proceeded at 50°C in an ultrasonic bath. Mercury was determined after both digestion procedures using a modified cold vapour atomic absorption spectrometric method, in which mercury generated on addition of a reducing agent is collected and subsequently atomized in a platinum-lined graphite furnace. The efficacy of the two digestion procedures was tested using various standard organic mercury compounds and it was found that only DP2 provided quantitative recoveries. Purification of the reagents required by DP2 was achieved using a mercury-selective ion-exchange resin, Chelite S, resulting in blank levels below 1.5 ng Hg l −1 . Both methods were applied to the determination of total mercury in an unpolluted marsh water sample, giving 2.0 ng Hg l −1 (DP1) and 2.7 ng Hg l −1 (DP2). The West German Standard digestion procedure (DP2) is recommended for the determination of total mercury in natural water samples.