Keywords:Arsenic speciation Microwave-assisted extraction Edible algae Inductively coupled plasma atomic emission spectrometry High performance liquid chromatography Hydride generation-atomic fluorescence spectrometry Twelve commercially available edible marine algae from France, Japan and Spain and the certified reference material (CRM) NIES No. 9 Sargassum fulvellum were analyzed for total arsenic and arsenic species. Total arsenic concentrations were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) after microwave digestion and ranged from 23 to 126 (xgg -1 . Arsenic species in alga samples were extracted with deionized water by microwave-assisted extraction and showed extraction efficiencies from 49 to 98%, in terms of total arsenic. The presence of eleven arsenic species was studied by high performance liquid chromatography-ultraviolet photo-oxidation-hydride generation atomic-fluorescence spectrometry (HPLC-(UV)-HG-AFS) developed methods, using both anion and cation exchange chromatography. Glycerol and phosphate sugars were found in all alga samples analyzed, at concentrations between 0.11 and 22 (xgg -1 , whereas sulfonate and sulfate sugars were only detected in three of them (0.6-7.2 (xgg -1 ). Regarding arsenic toxic species, low concentration levels of dimethylarsinic acid (DMA) (<0.9 (xgg -1 ) and generally high arsenate (As(V)) concentrations (up to 77 (xgg -1 ) were found in most of the algae studied. The results obtained are of interest to highlight the need to perform speciation analysis and to introduce appropriate legislation to limit toxic arsenic species content in these food products.

Several oxidant media were evaluated for the generation of lead hydride from slurry samples and their application to the determination of lead in vegetables and fish by hydride generation atomic absorption spectrometry. Three oxidant - acid media were compared: hydrogen peroxide - nitric acid, ammonium persulphate - nitric acid and potassium dichromate - lactic acid. The powdered samples were suspended in Triton X-100 and shaken with 10.0 g of blown zirconia spheres until a slurry was formed. The potassium dichromate - lactic acid medium was the most satisfactory for the determination of lead in fish and vegetables, providing the lowest detection limits as a result of its high sensitivity and low blank values. The ammonium persulphate - nitric acid medium gave good accuracy, precision and selectivity for vegetables (1-2 p.p.m. of lead); however, with fish (0.1-1 p.p.m. of lead) it was only a semi-quantitative medium for the determination of lead owing to its lack of sensitivity and selectivity. The hydrogen peroxide - nitric acid medium was unsatisfactory for the generation of lead hydride from slurry samples because of decomposition of hydrogen peroxide by the organic matter in the sample.

No abstract

A simple and rapid method is described for the determination of lead in foodstuffs and biological samples which corn bines a slurry procedure with lead hydride generation atomic absorption spectrometry (HGAAS). The powdered samples are suspended in Triton X-100 and shaken with 10.0 g of blown zirconia spheres until a slurry is formed. The determination of lead in slurries was carried out by HGAAS in an ammonium persulphatenitric acid medium. Several aspects were studied: the addition of an antifoaming agent; effect of varying the concentration of Triton X-100 on slurry stability and efficiency of lead hydride generation; and effect of slurry concentration. The method was used for the determination of lead in various food and biological samples. The results obtained showed good agreement between the slurry and wet-digestion procedures.

No abstract