A matrix solid-phase dispersion-gel permeation chromatography-programmed temperature vaporisation-GC-MS procedure for the analysis of polycyclic aromatic hydrocarbons in mussel samples.

A simultaneous matrix solid-phase dispersion extraction-gel permeation chromatography cleanup with programmed temperature vaporisation GC-MS determination is proposed for the analysis of parent and alkylated polycyclic aromatic hydrocarbons (PAHs) in mussel samples. The parameters affecting the extraction and elution efficiency were studied. Final conditions were: 0.5 g of mussel sample, 0.5 g diatomaceous earth as dispersant; and 4 g of Bio-Beads S-X3 for the gel permeation chromatography. Ethyl acetate/hexane (1:1, v/v) was selected for the elimination of the lipid fraction and the elution of PAHs. The detection and quantification limits achieved with this procedure were between 0.01 µg/kg and 0.67 µg/kg and 0.02 µg/kg and 1.93 µg/kg, respectively. The linearity of the method ranged between 5 µg/kg and 1000 µg/kg for most of the studied PAHs. The method was validated by the analysis of mussel tissue reference material (SRM 2977). The repeatability, intermediate precision and accuracy of the method obtained are in excellent agreement with the certified values. The proposed method is simple, precise and robust; no special instruments or costly equipment are required, and a reduction in the total time of analysis, sample handling and solvent consumption is achieved in comparison with classic procedures.

Pressurized liquid extraction followed by high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry for arsenic and selenium speciation in atmospheric particulate matter.

This paper describes the development of a chelating solvent-based pressurized liquid extraction (PLE) method for the simultaneous extraction of As and Se species (As(III), As(V), Se(IV) and Se(VI)) in atmospheric particulate matter (PM(10)). The extracted As and Se species were evaluated by high performance liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS). The feasibility of several pressurized chelating solvents was recently investigated to leach As and Se species from atmospheric particulate matter. The best results (high recoveries) were obtained when using EDTA. Experimental design approaches were used to achieve the best compromise conditions for the simultaneous extraction of As and Se species by EDTA-PLE. Analytical performances, such as limits of detection (in the range of 0.01-0.02 ng m(-3)), quantification (in the range of 0.02-0.07 ng m(-3)), and repeatability of the over-all procedure ( approximately 10%) were established. Finally, As and Se species were determined in several atmospheric particulate matter (PM(10)) samples collected in an urban area of A Coruña city (northwest coast of Spain) in 2006. In all the atmospheric particulate matter samples that were analysed, As(V) and Se(IV) (in the range of 0.17-0.60 ng m(-3)) were the major species found.

Determination of organic anions in atmospheric aerosol samples by capillary electrophoresis after reversed pre-electrophoresis.

This work presents the determination of low-molecular-mass (LMM) organic acids by CE after extraction with MeOH and preconcentration by evaporation. The interference arising from the simultaneous concentration of fast mobile anions (chloride, nitrate, and sulfate) at levels 200 times higher than those of LMM organic acids was reduced by the application of reversed pre-electrophoresis (RPE) as clean-up technique. This methodology allows for an effective elimination of high levels of fast mobile anions from the capillary before the separation has taken place, although analytes are also partially eliminated according to their electrophoretic velocities. In order to achieve an accurate quantification of organic anions, the use of a mathematical correction based on the linear relation between the analyte's effective volume removed during RPE and its mobility is proposed. Methods based on the use of one and two internal standards are discussed and evaluated. The proposed method is applied to the determination of organic acids in atmospheric particulate matter samples.

Capillary electrophoretic method for the determination of inorganic and organic anions in real samples. Strategies for improving repeatability and reproducibility.

Selectivity and robustness of the pyromellitic acid (PMA) based background electrolyte was improved in order to increase its applicability for routine analysis of inorganic and organic anions in real samples. An electrolyte composed of 6.75 mM PMA, 0.5 mM hexamethonium hydroxide as electroosmotic flow (EOF) modifier, Ca(2+) 0.05 mM as complexation agent and pH adjusted to 7.6 with TEA 1M allows for the separation of 22 inorganic and organic anions in less than 17 min. Good RSDs for within-day migration time reproducibility (0.03-0.9%) and day-to-day analyses (0.04-1.4%) were obtained by the use of two internal standards, allowing for an accurate compound identification. The detection limits ranged from 0.1 to 0.4 mgL(-1) (S/N=3) for hydrodynamic injection (1250 mbars). The applicability of the proposed method was demonstrated by the analysis of inorganic and organic anions in diverse real samples. The recoveries obtained ranged from 93 to 106%.

As, Bi, Sb and Sn determination in atmospheric particulate matter by direct solid sampling-hydride generation-electrothermal atomic absorption spectrometry.

A novel, rapid and simple method by hydride generation-electrothermal atomic absorption spectrometry (HG-ETAAS) after direct As, Bi, Sb and Sn hydrides generation from untreated filters of atmospheric particulate matter (PM(10) and PM(2.5)) was optimised. PM(10) and PM(2.5) were not subjected to any pre-treatment: circular portions between 0.28 and 6.28cm(2) were directly placed into the reaction vessel of a batch mode generation system. A 2(8)x3/64 Plackett-Burman design was used as a multivariate strategy for the evaluation of the effects of several variables affecting the hydride generation, trapping and atomisation efficiencies. Trapping temperature was the most statistically significant variable for As, Bi and Sn. Atomisation temperature was also statistically significant for Sb determination. Optimum values of significant variables were selected by using univariate optimisation approaches. An aqueous calibration method was used throughout. The developed method has been found to be precise with relative standard deviations of 6.2, 5.3, 9.1 and 7.5% for 11 determinations in a filter sample containing 0.7, 1.0, 1.4 and 1.7microg l(-1) for As, Bi, Sb and Sn, respectively. Results obtained by direct solid sampling-HG-ETAAS have been found statistically comparable with those obtained after conventional method based on an acid digestion followed to ICP-MS. Absolute detection limits were 37, 15, 30, and 41ng l(-1) for As, Bi, Sb and Sn, respectively. Detection limits referred to the air volume sampled (in the range of 0.020-0.050ng m(-3)) were low enough for the determination of several hydride-forming elements from PM(10) and PM(2.5) samples collected in a non-polluted suburban area of A Coruña (NW Spain).

Pressurized liquid extraction as a novel sample pre-treatment for trace element leaching from biological material.

Pressurized liquid extraction (PLE), commonly used for organic compounds extraction, has been applied for trace element leaching from marine biological material in order to determine major and trace elements (Al, As, Cd, Co, Cu, Fe, Hg, Li, Mn, Pb, Se, Sr, V and Zn). The released elements by formic acid PLE have been evaluated by inductively coupled plasma-optical emission spectrometry (ICP-OES). Different variables, such as formic acid concentration, extraction temperature, static time, extraction steps, pressure, mean particle size and diatomaceous earth (DE) mass/sample mass ratio were simultaneously studied by applying an experimental design approach (Plackett-Burman design (PBD) and central composite design (CCD)). Results showed that the extraction temperature was statistically significant (confidence interval of 95%) for most of the elements (high metal releasing was achieved at high temperatures). In addition, formic acid concentration was also statistically significant (confidence interval of 95%) for metals such as Cd and Cu. Most of the metals can be extracted using the same PLE operating conditions (formic acid concentration of 1.0 M, extraction temperature at 125 degrees C, static time of 5 min, one extraction step, extraction pressure at 500 psi and DE mass/sample mass ratio of 2). Taking in mind PLE requirements at the optimised operating conditions (125 degrees C), a time of 6 min is needed to pre-heat the cell. Therefore, the PLE assisted multi-element leaching is completed after 12 min. Analytical performances, such as limits of detection and quantification, repeatability of the over-all procedure and accuracy, by analysing GBW-08571, DORM-2, DOLT-3 and TORT-2 certified reference materials, were finally assessed.

Organochlorine pesticides accumulation and degradation products in vegetation samples of a contaminated area in Galicia (NW Spain).

The content of 21 organochlorine pesticides were studied in vegetation samples of a highly contaminated area by isomers of hexachlorocyclohexane (HCH) located close to a former industrial area in Galicia (NW Spain). Five species of plants were collected at different points of the contaminated area and the different parts of the plants were separated in order to study differences in accumulation capabilities. Samples were extracted employing microwave energy followed by a clean-up step using solid phase extraction and finally determined by GC-ECD. The results obtained show that the most abundant pesticides are HCHs isomers, being the main isomers beta-HCH and alpha-HCH in all samples whereas delta-HCH and gamma-HCH were at lower levels. Some other pesticides such as p,p'-DDT, p,p'-DDD and p,p'-DDE were also present in much lower amount in some of the samples. Several degradation products of HCH were also identified in some samples by GC-MS.

Direct determination of Ge in hot spring waters and coal fly ash samples by hydride generation-ETAAS.

A method for Ge determination in hot spring water and acid extracts from coal fly ash samples involving hydride generation, trapping and atomisation of the hydride generated from Ir-treated graphite tubes (GTs) has been developed. Hydride was generated from hydrochloric acid medium using sodium tetrahydroborate. Several factors affecting the hydride generation, transport, trapping and atomisation efficiency were studied by using a Plackett-Burman design. Results obtained from Plackett-Burman designs suggest that trapping and atomisation temperatures are the significant factors involved on the procedure. The accuracy was studied using NIST-1633a (coal fly ash) reference material. The detection limit of the proposed method was 2.4mugl(-1) and the characteristic mass of 233pg was achieved. The Ge concentrations in fly ash and hot spring samples were between 6.25-132mugg(-1) and 12.84-36.2mugl(-1).

Bismuth determination in environmental samples by hydride generation-electrothermal atomic absorption spectrometry.

A hydride generation procedure, via flow injection, coupled to electrothermal atomic absorption spectrometry was optimised for Bi determination in sea water and hot-spring water and acid extracts from coal, coal fly ash and slag samples. The effects of several variables such as hydrochloric acid and sodium tetrahydroborate concentrations, hydrochloric acid and sodium tetrahydroborate flow rates, reaction coil length, trapping and atomisation temperatures, trapping time and the Ar flow rate have been investigated by using a 2(9)*3/128 Plackett-Burman design. From these studies, certain variables (sodium tetrahydroborate concentration and trapping time) showed up as significant, and they were optimised by a 2(2)+star central composite design. In addition, a study of the bismuthine trapping and atomisation efficiency from graphite tubes (GTs) permanently treated with uranium, tantalum, lanthanum oxide, niobium, beryllium oxide, chromium oxide and tantalum carbide were investigated. The results obtained were compared with those achieved by iridium and zirconium-treated GTs. The best analytical performances, with characteristic mass of 35 pg and detection limit of 70 ng l(-1), were achieved by using U-treated GTs. Accuracy were checked using several reference materials: 1643d (Trace Elements in Water), TM-24 (Reference Water), GBW-07401 (Soil) and 1632c (Trace Elements in Coal).