Ociel Munoz

Optimization of the solubilization, extraction and determination of inorganic arsenic [As(III)+As(V)] in seafood products by acid digestion, solvent extraction and hydride generation atomic absorption spectrometry

A method for the selective quantitative determination of inorganic arsenic [As(III) + As(V)] in seafood was developed. In order to do so, various procedures for the solubilization and extraction of inorganic arsenic quoted in the literature were tested. None provided satisfactory recoveries for As(III) and As(V) in real samples. Consequently, a methodology was developed which included solubilization with HCl and subsequent extraction with chloroform. The arsenic was solubilized in 9 mol l-1 hydrochloric acid. After reduction by hydrobromic acid and hydrazine sulfate, the inorganic arsenic was extracted into chloroform, back-extracted into 1 mol l-1 HCl, dry-ashed, and quantified by hydride generation-atomic absorption spectrometry (HG-AAS). The analytical features of the method are as follows: detection limit, 3.07 ng g-1 As (fresh mass); precision (RSD), 4.0%; recovery, As(III) 99%, As(V) 96%. In the optimized conditions, other arsenic species--dimethylarsinic acid (DMA), arsenobetaine (AB), arsenocholine (AC) and tetramethylarsonium-ion (TMA+)--were not co-extracted. However, different percentages of minor species were extracted with chloroform: monomethylarsonic acid (MMA) 100%, and trimethylarsine oxide (TMAO) 3-10%. Real samples and reference materials of seafood (DORM-1, DORM-2, TORT-2, CRM-278 and SRM-1566a) were analyzed. The analysis of DORM-1 provided an inorganic arsenic value of 124 +/- 4 ng g-1 As, dry mass (dm), which is very close to the value obtained by other authors using high performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) and ionic chromatography-hydride generation-atomic absorption spectrometry (IC-HG-AAS).

Accumulation of heavy metals and As in wetland birds in the area around Doñana National Park affected by the Aznalcollar toxic spill

The impact of the spill from the mine in Aznalcollar (Seville, Spain) on waterfowl in the Doñana National Park is assessed. The concentrations of Cu, Pb, Cd, Zn nd As in the liver and eggs of 16 species of waterfowl found dead in the Park between April and November 1998 were determined. The highest levels were found for Zn, followed by Cu, Pb, Cd and As. The main parameters related to the accumulation of these elements in the waterfowl studied were species and trophic level. The other variables studied--distance from the spill, days of exposure, sex, size, and age--are important, although this depends on the element studied. Zn and Cu from the spill have entered the food chain of the aquatic birds studied, but Cd, Pb and As have not. There is currently no evidence to suggest that the trace element concentrations measured have reached toxic levels.

Trace elements in blood collected from birds feeding in the area around Donana National Park affected by the toxic spill from the Aznalcollar mine

A long-term monitoring plan was established to study if bird populations around Doñana National Park were affected by the toxic spill from the Aznalcóllar mine. The concentrations of Zn, Pb, As, Cu, Sb, Co, Tl and Cd in the blood of 11 bird species feeding in the area were determined. The parameters which most affect the accumulation of trace elements in the birds studied are, firstly, species and secondly, trophic position, sex, days of exposure and weight. In some individuals, Zn and Cu occurred at higher levels than the reference values for contaminated areas. Concentrations of Pb and Cd in a considerable number of individuals were higher than those found in birds from uncontaminated areas. The present data, together with the lack of data on blood metal concentration prior to the spill, do not offer any conclusive evidence of the influence of the spill on avian blood metal concentrations.

Total and inorganic arsenic in the fauna of the Guadalquivir estuary: environmental and human health implications.

To evaluate the impact on fauna of the release of toxic waste from the tailings dam operated by the Boliden Apirsa S.L company at Aznalcóllar, Seville (Spain) a study was carried out of total and inorganic arsenic contents in 164 samples from six different estuary species, including molluscs, crustaceans and fish, collected at six sampling stations distributed along the estuary and mouth of the River Guadalquivir. The contents found, expressed in micrograms per gram wet weight, were as follows. Total arsenic: Crassostrea angulata--giant cupped oyster (2.44 +/- 0.45); Scrobicularia plana--peppery furrow (2.50 +/- 0.73); Palaemon longirostris--delta prawn (1.33 +/- 0.54); Uca tangeri--AfroEuropean fiddler crab (1.76 +/- 0.08); Melicertus kerathurus--shrimp (3.60 +/- 1.92); and Liza ramada--mullet (0.65 +/- 0.38). Inorganic arsenic: C. angulata (0.09 +/- 0.02); S. plana (0.38 +/- 0.23); P. longirostris (0.04 +/- 0.01); U. tangeri (0.22 +/- 0.03); M. kerathurus (0.03 +/- 0.01); and L. ramada (0.03 +/- 0.03). The levels of total As are comparable to those obtained by other authors. With respect to inorganic arsenic, only S. plana and U. tangeri present high levels of inorganic arsenic. This may be due to the fact that these organisms live in estuary sediments, reservoirs of inorganic arsenic, and ingest particles of sediments during feeding. Because of the lack of information for this area concerning previous levels of total and inorganic arsenic in the species analysed, it was not possible to establish the impact on the fauna of the River Guadalquivir estuary of the toxic spill resulting from the failure of the mine tailings dam at Aznalcóllar. With respect to the implications to human health as a result of consumption of species from the Guadalquivir estuary, only with the species Scrobicularia plana, as a high consumption of this mollusc might, in some cases, exceed the maximum tolerable intake for inorganic arsenic indicated by the FAO/WHO. Consumption of the liver of L. ramada does not appear to present problems to human health.

Rapid and quantitative release, separation and determination of inorganic arsenic [As(III)+As(V)] in seafood products by microwave-assisted distillation and hydride generation atomic absorption spectrometry

A precise, simple and rapid method is described for the determination of inorganic arsenic [As(III)+As(V)] in seafood products. The inorganic species were isolated from the matrix by microwave-assisted distillation and determined by hydride generation atomic absorption spectrometry (HGAAS). The microwave and chemical parameters were optimized in order to obtain quantitative inorganic arsenic recoveries. The analytical features of the method are as follows: detection limit 10 ng g –1 (dry mass) or 2 ng g –1 (fresh mass); precision (RSD) 4%; recoveries 106±3% for As(III) and 113±4% for As(V). Under the optimized conditions, arsenobetaine, arsenocholine and tetramethylarsonium ion added to samples of seafood were not distilled; however, minor species were distilled and were detected in various percentages: 109% monomethylarsonic acid; 11% dimethylarsinic acid; 0.2% trimethylarsine oxide. The concentrations expressed as arsenic contributed by these species would imply a mean overestimate of inorganic arsenic of about 24 ng g –1 dry mass (dm). The concentrations of inorganic arsenic found in natural seafood samples ranged between 0.053 and 1.145 µg g –1 (dm) (mean moisture content 78%). The procedure was compared with an alternative methodology in which acid digestion-solvent extraction-HGAAS was used for the determination of inorganic arsenic. A Students t-test for paired samples of the data obtained by the two methodologies showed no significant differences (P-value 0.66).