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.
Synergistic Effect of High Temperature and High pH on the Destruction of Salmonella enteritidis and Escherichia co1i O157:H7.
This study was undertaken to determine if high temperature and high pH interact synergistically to enhance the rate of destruction of two important gram-negative foodborne pathogens, Escherichia coli O157:H7 and Salmonella enteritidis . The rates of destruction in NaHCO3-NaOH buffers at pH 7.0, 10.0, and 11.0 were determined at 35, 40, 45, 50, 55, 60, and 65°C. Use of an improved heating protocol eliminated a "tailing effect" at longer exposure times. The present study demonstrated that the combination of high pH and high temperature resulted in a highly significant synergistic interaction (P > F = 0.0001), which caused rapid death of both E. coli O157:H7 and S. enteritidis . This "alka-therm" technology might be used commercially to destroy gram-negative foodborne pathogens on various raw agricultural commodities.