Esmeralda Millán

Evaluation of heavy metal availability in polluted soils by two sequential extraction procedures using factor analysis.

Superficial soil and grass samples from 13 locations affected by several anthropogenic sources (mining, metal factory, traffic emissions) were collected in Gipuzkoa, northern Spain. The more labile metal fractions, the mobile (extracted by 0.01 mol l(-1) CaCl(2)) and the mobilisable (extracted by 0.005 mol l(-1) DTPA), were evaluated using a short sequential procedure with two steps. From the results a short-medium term potential lability of Cd, Cu, Zn and Pb can be concluded. The labile levels were compared with the results obtained using the Tessier sequential procedure. Factor analysis was used to check the associations between the total metal contents in soil and grass, as well as between the levels of the different sequential fractions and the total content in grass. Cd, Cu and Zn labile levels were related to total metal grass contents indicating its suitability for the availability studies in polluted soil-plant system.

Assessment of Cd, Pb and Zn contamination in roadside soils and grasses from Gipuzkoa (Spain)

Abstract Superficial soils and grasses at two distances from eight different locations near to roads varying traffic flow were collected in July of 1992 and July of 1994. Total (soil and grass) and DTPA=extractable (soil) contents of Cadmium, Copper, Iron, Manganese, Lead and Zinc were determined by Atomic Absorption Spectroscopy. Remarkable high levels of Pb and Zn in the nearest point to A-8 highway were found. The application of statistical treatment showed for Cd, Cu, Pb and Zn significant correlations between DTPA-extractable and total contents and also the variability with distance and locations. However, the 1992 and 1994 samplings did not significantly differ neither in the total concentrations nor in the extractable levels. Using factor analysis a strong association among Cd, Pb and Zn indicating the same pollution source was found.

Evaluation of heavy metal availability in contaminated soils by a short sequential extraction procedure

A short sequential procedure for the determination of the more readily available metal fractions in soils is presented. These fractions are the mobile (extracted by 0.01 mol l−1 CaCl2) and mobilisable (extracted by DTPA). The method was tested with three soils affected by different anthropogenic sources of pollution: mining, steel factory and traffic emissions. From the results, a potential order of metal availability in these soils is proposed: Cd>Pb>Zn∼Cu>Mn>Ni>Fe∼Cr. Different percentages of available metals, mobile plus mobilisable, were found in the three soils. The method was compared with the results obtained following two widely used extraction procedures. A substantial time saving was achieved by using the method proposed in the present work.

Polychlorinated biphenyls in Spanish adults: Determinants of serum concentrations

BACKGROUND Polychlorinated biphenyls (PCBs) are persistent compounds that may pose an environmental hazard to humans, food being the main source of exposure for the general population. OBJECTIVE To measure the serum concentrations of the main PCBs in subjects from the general population in Spain, and to assess potential determinants of such concentrations. METHODS Serum was obtained from blood samples of 953 subjects aged 35-64 years, residents in five Spanish regions (three from the North and two from the South), randomly selected from the EPIC-Spain cohort. Blood collection took place during 1992-1996 and four PCB congeners (118, 138, 153 and 180) were determined by means of gas chromatography with electron-capture detection (GC-ECD). RESULTS The concentration of total PCBs was 459 ng/g lipids (or 3.1 microg/l); the corresponding figures for PCB 153 were 186 ng/g lipids and 1.25 microg/l. Men had higher values than women, PCB levels increased with age, and serum concentration of PCBs was higher in northern regions. Body mass index (BMI) was inversely related to PCB concentrations, and fish intake was the dietary factor showing the greatest association with serum PCBs. The pattern described was similar for each congener separately. CONCLUSIONS We found concentrations similar to those reported in European countries where blood collection was carried during the same period. Regional differences within Spain are not fully explained by anthropometric or dietary factors. The inverse association with BMI suggests that in the mid-1990s there was still ongoing or recent exposure to PCBs in Spain.

Assessment of tin and butyltin species in estuarine superficial sediments from Gipuzkoa, Spain

Ten superficial sediments from river estuaries of Gipuzkoa (North Spain) were collected and analyzed for nine metals (including tin, Sn) and butyltin compounds (monobutyltin, MBT; dibutyltin, DBT; tributyltin, TBT). Total metal concentration in the fine fraction (<63 micrometer) of the sediment was determined in aqua regia--hydrofluoric acid extracts by atomic absorption spectrometry. The butyltin species (BTs) were firstly extracted from the sediments with hydrochloric acid-methanol mixture. After derivatization with sodium tetraethyl borate, the organotin compounds were extracted by solid phase microextraction (SPME) in headspace mode. A fiber coated with 100 micrometer poly(dimethylsiloxane) was used for SPME. The organotin species were analyzed by gas chromatography-flame ionization detection. Analysis of the certified reference sediment (PACS-2) shown the suitability of the procedures for determination of metal contents and DBT-TBT species in contaminated sediments. Factorial analysis was used to examine the main sources of metals. Three factors represented more than 89% of the total variance of the metal system, and the Sn was related with Cu-Zn-Pb suggesting the same pollution source. The BTs concentrations in the area were high (TBT ranged from 0.05 to 5.48 mg Sn kg(-1)). The percentage of total butyltin species ( summation operator BTs) respect to the total Sn amount was higher than 4% in all the sediments, showing in the Bidasoa river estuary a remarkable value higher than 20%. Hence, the studied estuarine sediments reflect a pollution that is related with historical industrial and fishing activities of the area.

Optimization of headspace solid-phase microextraction by means of an experimental design for the determination of methyl tert.-butyl ether in water by gas chromatography-flame ionization detection.

A procedure for determination of methyl tert.-butyl ether (MTBE) in water by headspace solid-phase microextraction (HS-SPME) has been developed. The analysis was carried out by gas chromatography with flame ionization detection. The extraction procedure, using a 65-microm poly(dimethylsiloxane)-divinylbenzene SPME fiber, was optimized following experimental design. A fractional factorial design for screening and a central composite design for optimizing the significant variables were applied. Extraction temperature and sodium chloride concentration were significant variables, and 20 degrees C and 300 g/l were, respectively chosen for the best extraction response. With these conditions, an extraction time of 5 min was sufficient to extract MTBE. The calibration linear range for MTBE was 5-500 microg/l and the detection limit 0.45 microg/l. The relative standard deviation, for seven replicates of 250 microg/l MTBE in water, was 6.3%.

Development and application of a screening method for triazole fungicide determination in liquid and fruit samples using solid-phase microextraction and HPLC-DAD

A screening method for determination of six triazole fungicides (diniconazole, fluquinconazole, flusilazole, myclobutanil, tebuconazole and tetraconazole) using the solid-phase microextraction (SPME) technique coupled to a high-performance liquid chromatography-diode array detector (HPLC-DAD) was developed. Experimental variables were chosen and their values were fixed according to an experimental design with the steps of screening (25−1 fractional factorial design) and optimization of the significant variables (central composite design). Using polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibers, the other experimental conditions were: extraction time, 90 min; extraction temperature, 60 °C; NaCl addition, 180 g L−1; static desorption mode and desorption time, 2 min. The method showed good inter and intraday precision (RSD values less than 13.2%) and the limits of detection were from 1.5 to 5.9 μg L−1 in liquid extracts and from 0.08 to 0.3 mg kg−1 in solid products. The method was applied to grape and apple fruit samples previously sprayed with commercial products containing the analytes. Samples were taken from peel, pulp and juice following a pre-harvest interval of two weeks. Also, rain samples under the fruit trees were collected. Myclobutanil and tebuconazole were found in the peel and rain, but not in pulp and juice samples.

Optimization and validation of a nonaqueous micellar electrokinetic chromatography method for determination of polycyclic musks in perfumes

A nonaqueous micellar electrokinetic chromatography method was developed for determination of Tonalide®, Galaxolide®, and Traseolide® polycyclic musks (PCMs). These compounds are widely used as fragrance ingredients in cosmetics. The method was optimized by using a three variable Box-Behnken experimental design and response surface methodology. A modified chromatographic response function was defined in order to adequately weigh the terms in the response function. After optimization of experimental conditions, an electrolyte solution of 195 mM SDS and 40 mM NaH(2) PO(4) in formamide was selected for the separation of the three PCMs, and the applied voltage was fixed at 30 kV. The nonaqueous MEKC method was then checked in terms of linearity, limits of detection and quantification, repeatability, intermediate precision and accuracy, providing appropriate values (i.e. RSD values for precision never exceeding 7%, and accuracy 96-107%). Nonaqueous MEKC for determination of the selected compounds was successfully applied to the analysis of commercial perfume samples.

Optimisation of tin determination in aquaregia–HF extracts from sediments by electrothermal atomicabsorption spectrometry using experimental design

An experimental design was applied to optimise total tin (Sn) determination in aqua regia–HF extracts from sediments. Determination was performed by electrothermal atomic absorption spectrometry using palladium as chemical modifier. A full factorial design for screening and a central composite design for optimisation were used for evaluation of the effects of several variables. The results showed that the pyrolysis temperature, the atomisation temperature and the modifier concentration exerted an influence on the determination. Accuracy and precision were checked using the reference material PACS-2. The results obtained were statistically, at the 95% confidence level, indistinguishable from the certified values. The limit of detection was 0.048 mg kg−1. The optimised method was applied to the analysis of estuarine superficial sediments from Gipuzkoa (Spain). The total tin in these samples ranged from 9 to 37 mg kg−1.

Heavy metal contents from road soils in Guipúzcoa (Spain)

Abstract The heavy metal contents of five sampling points adjacent to roads of varying traffic flow in Guipuzcoa (Spain) were determined. At every point two topsoil samples separated 2–3 m were taken in July 1991. The soil samples were digested with aqua regia and extracted with DTPA. Cd, Cu, Fe, Mn, Ni, Pb and Zn were determined by flame or graphite furnace atomic absorption spectrophotometry. Significant correlations between aqua regia metal levels and DTPA-extractable metal levels were found for Zn, Pb, Cu, Cd and Ni. Most of the metal levels decreased with distance from the source of pollution. The quantity of several metals, mainly Pb and Zn, in the samples increased with the traffic flow. There was a point where the proximity of an industrial area had a major effect on the quantity of several metals.