Optimisation of selective alkaline extraction for Cr(VI) determination in dairy and cereal products by HPIC-ICPMS using an experimental design.

This study presents the optimisation through an experimental design then the validation of a method to determine Cr(VI) in certain foodstuffs by high-performance ionic chromatography with inductively coupled plasma mass spectrometry. This method is free from interferences possibly associated with chloride and organic or inorganic carbon. Analytical performances assessed by the accuracy profile method were satisfactory in terms of linearity, specificity, sensitivity, accuracy, repeatability and intermediate precision. Limits of quantification ranged from 0.6µg.kg(-1) in dairy products to 0.8µg.kg(-1) in cereal products. The method was applied to the determination of Cr(VI) in dairy and cereal products from different brands and origins. Despite the method's very high sensitivity, Cr(VI) was not found in all the studied samples. This confirms the results of the most recent studies using an on-line speciation method, and invalidates older studies that found traces of Cr(VI) in food by using a less specific off-line speciation method.

Distribution and relationships of As, Cd, Pb and Hg in freshwater fish from five French fishing areas.

The concentrations of arsenic, cadmium, mercury and lead in 149 muscle samples of eight freshwater fish species (European eel, bream, common carp, European catfish, roach, perch, pike and pikeperch) from five different French fishing areas from contaminated and control sites were measured by inductively coupled plasma mass spectrometry after microwave digestion under pressure. No significant correlation was found between the condition factor (CF), based on the length-mass relationship, and As, Cd and Pb levels in all the samples analysed, but a positive correlation was detected between CF and Hg levels (P<0.0001, R=0.49). Positive correlations with body length were only found for Hg in roach (P<0.05, R=0.32) and Pb in bream (P<0.05, R=0.48) and correlations with both body weight and length were also found for Hg in pike (P<0.05, R=0.90 and 0.86) and Cd in European eel (P<0.01, R=-0.35 and -0.37). The average content and the standard deviation in fish muscle samples was 0.007±0.012, 0.102±0.077, 0.142±0.097 and 0.035±0.053 mg kg(-1) of wet mass for Cd, As, Hg and Pb, respectively. Significant differences were established between groups of predatory fish and non-predatory fish for Hg and Pb, and between control and contaminated sites in the whole selection and also within feeding guilds, i.e. the values of Hg in the benthophagic fish were significantly different between these sites. Finally, these results were also compared for each species with previous French and European studies.

Li, Cr, Mn, Co, Ni, Cu, Zn, Se and Mo levels in foodstuffs from the Second French TDS.

In 2006, the French Food Safety Agency (AFSSA) conducted the Second French Total Diet Study (TDS) to estimate dietary exposures to the main minerals and trace elements from 1319 samples of foods typically consumed by the French population. The foodstuffs were analysed by inductively coupled plasma-mass spectrometry (ICP-MS) after microwave-assisted digestion. Occurrence data for lithium, chromium, manganese, cobalt, nickel, copper, zinc, selenium and molybdenum were reported and compared with results from the previous French TDS. The results indicate that the food groups presenting the highest levels of these essential trace elements were "tofu" (for Li, Mn, Ni, Cu, Zn and Mo),"fish and fish products" particularly "shellfish" (for Li, Co, Cu, Zn, Se and Mo), "sweeteners, honey and confectionery" particularly dark chocolate (for Cr, Mn, Co, Ni and Cu), "cereals and cereal products" (for Mn, Ni and Mo) and "ice cream" (for Cr, Co and Ni).

Optimisation of ICP-MS collision/reaction cell conditions for the determination of elements likely to be interfered (V, Cr, Fe, Co, Ni, As and Se) in foodstuffs.

A strategy for the accurate determination in foodstuffs of seven elements liable to be interfered with (V, Cr, Fe, Co, Ni, As and Se), was successfully applied. Firstly, to reduce spectroscopic interferences, four influential factors (hexapole and quadrupole bias, helium and hydrogen flows) of the collision/reaction cell device were optimised through the experimental design methodology. Secondly, non-spectroscopic interferences, which may severely disturb the analysis of matrices containing large amounts of non-target elements, were significantly reduced by a limited decrease in the flow rate of the optimum initial nebuliser rather than with a specific time-consuming dilution. Finally, the optimised multi-element method was subjected to a full validation that demonstrated its acceptable analytical performance.

Pb, Hg, Cd, As, Sb and Al levels in foodstuffs from the 2nd French total diet study.

In 2006, the French Food Safety Agency (AFSSA) conducted the second French total diet study (TDS) to estimate dietary exposures of main minerals and trace elements from 1319 samples of foods habitually consumed by the French population. The foodstuffs were analysed by ICP-MS after microwave-assisted digestion. Contamination data for lead, mercury, cadmium, arsenic, antimony and aluminium were reported and compared with results from the previous French total diet study. The results are comparable with those from the rest of Europe. "Fish and fish products" and "sweeteners, honey and confectionery" were the food groups showing the highest cumulated contents in Pb, Hg, Cd, As, Al and Sb. However, observed levels remained low and were generally well below the maximum levels set by the current European regulation for lead, cadmium and mercury.

Determination of calcium, magnesium, sodium, and potassium in foodstuffs by using a microsampling flame atomic absorption spectrometric method after closed-vessel microwave digestion: method validation.

This paper describes a validation process in compliance with the NFIEN ISO/IEC 17025 standard for the determination of the macrominerals calcium, magnesium, sodium, and potassium in foodstuffs by microsampling with flame atomic absorption spectrometry after closed-vessel microwave digestion. The French Standards Commission (Agence Francaise de Normalisation) standards NF V03-110, NF EN V03-115, and XP T-90-210 were used to evaluate this method. The method was validated in the context of an analysis of the 1322 food samples of the second French Total Diet Study (TDS). Several performance criteria (linearity, LOQ, specificity, trueness, precision under repeatability conditions, and intermediate precision reproducibility) were evaluated. Furthermore, the method was monitored by several internal quality controls. The LOQ values obtained (25, 5, 8.3, and 8.3 mg/kg for Ca, Mg, Na, and K, respectively) were in compliance with the needs of the TDS. The method provided accurate results as demonstrated by a repeatability CV (CVr) of < 7% and a reproducibility CV (CVR) of < 12% for all the elements. Therefore, the results indicated that this method could be used in the laboratory for the routine determination of these four elements in foodstuffs with acceptable analytical performance.