M.C. López

Determination of total arsenic levels by hydride generation atomic absorption spectrometry in foods from south-east Spain: estimation of daily dietary intake

The total concentration of arsenic in different foods from south-east Spain was determined by hydride generation atomic absorption spectrometry. Mineralization was carried out with an HNO3-HClO4 mixture in a thermostated sand bath. Arsenic determination was performed by the standard addition method. Analyses of NIST and CBR-CEC reference materials demonstrated the reliability and accuracy of the technique. The highest arsenic levels were found in seafood, cereals, meat and meat by-products. In meat and meat by-products, the total arsenic measured in meat was significantly higher than that in sausages (p<0.05). In cereals, arsenic concentrations in corn and white rice samples were significantly higher (p<0.01) than those measured in wheat by-products. Mean arsenic concentrations in cheese were statistically lower than those in other dairy products (p<0.01). New data have been provided on the total arsenic content of a variety of foods in Spain, which is important for making exposure estimates. The estimated daily intake of total arsenic in the Spanish diet was 221 μg As day−1.

Chromium in basic foods of the Spanish diet: seafood, cereals, vegetables, olive oils and dairy products.

In the present study, graphite furnace atomic absorption spectrometry (GFAAS) was used to determine the content of total chromium in some basic foods of the Spanish diet. The seafood samples, vegetables and olive oils were mineralized previously with HNO3 and V2O5. A procedure of slurries with Triton X-100 was applied to dairy products. The temperature-time program was optimized for every type of sample. An assessment of the analytical characteristics of the method verifies their reliability. The content of Cr ranged between 0.004 and 0.079 microg/g in seafood (fresh wt.), from 0.007 to 0.456 microg/g in cereals and vegetables (fresh wt.), between not detectable and 0.625 microg/g in dairy products and between not detectable and 0.040 microg/g in olive oils. The high consumption of these products conditions the fact that they should be significant sources of Cr in the diet.

Determination of selenium in serum by hydride generation atomic absorption spectrometry for calculation of daily dietary intake

Hydride generation atomic absorption spectrometry was used to determine the selenium concentrations in 130 samples of human serum from a control group of inhabitants in the southern part of the province of Granada (Spain). The mean selenium concentration in serum was 74.9 micrograms/l. This concentration did not vary significantly (P > 0.05) in relation to the sex of the subject, with concentrations of 80.6 micrograms/l in men and 70.7 micrograms/l in women. These mean values correspond to a mean daily dietary selenium intake of 50.4 micrograms per day in men and 44.6 micrograms per day in women. A considerable number of the individuals in the study area therefore have a daily selenium intake lower than the recommended dietary allowance of 70 micrograms per day for men and 55 micrograms per day for women. Likewise, the measured selenium concentrations in the basic health zones of the area were not statistically different (P > 0.05). The differences in selenium concentration between subjects in coastal zones and mountainous zones are therefore not significant.

Microwave dissolution for the determination of mercury in fish by cold vapour atomic absorption spectrometry

Abstract A procedure is described for the determination in fish species from the Mediterranean Spanish coast by cold vapour atomic absorption spectrometry. The samples were decomposed with nitric acid in a microwave acid digestion bomb. A certified reference sample was analysed and the results obtained agreed well with the certified values. The limit of detection for the samples investigated was 0.195 ng ml −1 . The concentrations of mercury in fish ranged from 0.033 to 1.211 μg g −1 .

Chromium levels in spices and aromatic herbs.

We determined the presence of chromium in a total of 72 samples of 17 different spices and aromatic herbs. Electrothermal atomization atomic absorption spectrometry (ETA-AAS) was used to determine Cr content in the samples mineralized with HNO3 and V2O5. The analytical characteristics of the proposed method were tested, and the accuracy and precision was also verified against an NBS-certified reference material. Chromium concentrations ranged from not detectable to 1.42 micrograms/g (dry wt.) and Cr presence was detected in 95% of samples. Spices and aromatic herbs are widely consumed in the Spanish diet and in the Mediterranean diet, in general.

Chromium levels in potable water, fruit juices and soft drinks: influence on dietary intake.

Potable water, fruit juices and soft drinks are some of the most widespread beverages in the habitual diet, and they can contribute to chromium dietary intake. We determined the concentration of chromium in 90 different samples of beverages widely consumed in Spain. Graphite furnace atomic absorption spectrometry was used to analyze samples processed with a HNO3-V2O5 acid digestion pretreatment. In water samples Cr was directly determined. We verified the sensitivity, accuracy and precision of the method and ruled out matrix interferences. In analyzed samples, chromium values ranged from not detectable to 11.80 micrograms/l in potable water, from not detectable to 17.60 micrograms/l in fruit juices and from 3.60 to 60.50 micrograms/l in soft drinks. The chromium levels we encountered are low and the contribution of non-alcoholic beverages to dietary intake of this element, have been estimated to be 0.41 microgram/day in the common Spanish diet.

Cadmium levels in wine, beer and other alcoholic beverages: possible sources of contamination

An accurate and precise method is described for the direct determination of Cd in wine, beer and other alcoholic beverages by electrothermal atomization-atomic absorption spectrometry (ETA-AAS). The graphite furnace program was optimized and samples were pretreated with nitric acid and pentoxide vanadium in a digestion block at 120 degrees C for 90 min. The results obtained were validated against microwave acid sample digestion. The analytical detection limit was 0.5 pg. The proposed method was applied to determine Cd in 134 samples of 10 different alcoholic beverages. The mean values ranged from 0.10 to 15.38 microg/l in wine, from not detectable to 0.80 microg/l in beer, and from not detectable to 11.52 microg/l in other alcoholic beverages such as cider, brandy, rum, whisky, gin, anisette, liquor and spirits. The wide variability of the results obtained emphasizes the multiplicity of factors that can influence the presence of Cd in these products. Because alcoholic beverages are widely consumed, they contribute a large fraction of cadmium intake, and therefore, strict control of this element is advisable.

Zinc levels in foods from southeastern Spain: relationship to daily dietary intake

The zinc content of 300 food and 79 beverage samples was determined using flame atomic absorption spectrometry. Sample recoveries, repeatability, and analyses of NIST and CBR-CEC reference materials demonstrated the reliability and accuracy of this technique. Mean zinc concentrations varied from 0.02 μg/ml in fresh water to 71.0 μg/g (fresh weight) in pork liver. The daily dietary intake of zinc for inhabitants of southeastern Spain was estimated to be 10.1 mg (5.5, 4.0, 0.5, and 0.1 mg Zn/day per person from foods of animal and vegetable origin, drinks, and other foods, respectively). Zinc levels found in high protein foods (meat, fish, milk products, eggs, dry fruits, cereals and legumes) were significantly higher than those found in food with a low protein content (vegetables, fruits and drinks) (p < 0.001). A significant linear correlation between zinc levels and the corresponding protein content of cereals, legumes and dry fruits was found (r = 0.754, p < 0.005). Zinc concentrations in milk samples were significanlty modified by the thermal treatment (p < 0.001), and the skimming (p < 0.05) and calcium enrichment processes (p < 0.001). Shellfish zinc levels were also significantly higher than those measured in fish (p < 0.05). Mean zinc concentrations found in cheese were statistically higher than those determined in the remaining milk products (p < 0.001). Zinc levels measured in distilled beverages were also statistically lower than those found in fermented ones (p < 0.001).

Aluminium levels in spices and aromatic herbs

We evaluated the levels of aluminium in a total of 72 samples of 17 different spices and aromatic herbs that are widely consumed in Spain, and in the Mediterranean diet, in general. Aluminium was determined in the samples mineralized with HNO3 and V2O5, using electrothermal atomization atomic absorption spectroscopy as the analytical technique. The accuracy and precision of the proposed method was verified against an NBS-certified reference material. Precision, expressed as relative standard deviation, ranged from 1.10 to 4.07%. The results obtained from recovery studies were of 97.90 +/- 1.20. Aluminium concentrations ranged from 3.74 to 56.50 microg/g (dry wt.). The presence of this metal was detected in all the samples we analysed.

The effect of industrial pollution on mercury levels in water, soil, and sludge in the coastal area of Motril, Southeast Spain

The total concentration of mercury was determined in samples of water, soil and sludge from the Mediterranean coastal area of Southeast Spain (Motril), where Hg contamination is produced primarily by a local paper mill. Samples were taken at surface level in a 5 Km radius from the factory. The total Hg concentrations varied from 0.117 to 0.760 μg/g in soil and sludge, and from ND to 2.088 μg/L in water. A negative correlation was observed between the distance of the sampling station from the mill and the concentration of Hg in the soil and sludge samples. Similarly, an increase in Hg concentration was observed in the freshwater and wastewater after passing close to the factory.