Comparison of different coatings in solid-phase microextraction for the determination of organochlorine pesticides in ground water.

A solid-phase microextraction (SPME) procedure using three commercialised fibers (Carbowax-divinylbenzene, Carboxen-polydimethylsiloxane and divinylbenzene-Carboxen-polydimethylsiloxane) is presented for the determination of a selected group of organochlorine compounds in water samples. The extraction performances of these compounds were compared using fibers with two and three coatings. The optimal experimental procedures for the adsorption and desorption of pesticides were determined. The limits of detection with the divinylbenzene-Carboxen-polydimethylsiloxane fiber at levels below ng l(-1) were similar or lower than values presented in the literature for several of these compounds using polydimethylsiloxane fiber. The advantages of using this fiber, such as no salt addition, are discussed. Finally, the optimised procedures were applied successfully for the determination of these compounds in polluted ground water samples.

Optimisation of a solid-phase microextraction procedure for the determination of triazines in water with gas chromatography-mass spectrometry detection.

A procedure based on solid-phase microextraction (SPME) and gas chromatography-mass spectrometry, operating in the chemical ionisation mode, was developed and optimised in order to determine 10 triazines in water samples. Five different SPME fibers available for analysis [polydimethylsiloxane (PDMS) 100 microm, polyacrylate (PA) 80 microm, PDMS-divinylbenzene (DVB) 65 microm, Carbowax (CW)-DVB 65 microm, and Carboxen (CAR)-PDMS 75 microm] were tested, and PDMS-DVB was selected. To enhance the sensitivity of the SPME, variables affecting adsorption and desorption steps such as temperature, time, pH and ionic strength of the solution were optimised. Detection limits obtained were ranged between 2 and 17 ng l(-1), and precision values were below 8% for the selected PDMS-DVB fiber. The optimised method was applied to real water samples and no triazines were detected.

Determination of esters in dry and sweet white wines by headspace solid-phase microextraction and gas chromatography.

Headspace solid-phase microextraction (HS-SPME) was studied for the high-resolution gas chromatographic (HRGC) analysis of esters in wines. Five different SPME fibers were tested and the influence of different factors such as temperature and time of desorption, extraction time, extraction technique, stirring, sample and vial volume, sugar and ethanol content were studied and optimised using model solutions. The proposed HS-SPME-GC method is an appropriate technique for the quantitative analysis of esters in dry and sweet white wines.

Determination of lactones in wines by headspace solid-phase microextraction and gas chromatography coupled with mass spectrometry.

Application of headspace solid-phase microextraction (HS-SPME) coupled with high-resolution gas chromatographic (HRGC) analysis was studied for determining lactones in wines. Six different SPME fibers were tested, and the influence of different factors such as temperature and time of desorption, ionic strength, time of extraction, content of sugar, ethanol, tannins and anthocyanins, and pH and influence of SO2 were studied. The proposed HS-SPME-GC method is an appropriate technique for the quantitative analysis of γ-butyrolactone, γ-hexalactone, trans-whiskey lactone, γ-octalactone, cis-whiskey lactone, γ-nonalactone, γ-decalactone, δ-decalactone, and γ-undecalactone in wines. Method reproducibility and repeatability ranged between 0.6 and 5.2% for all compounds. Detection limit for γ-butyrolactone was 0.17 mg/L and a few µg/L for the rest of the compounds. The optimized method has been applied to several wine samples.

Evaluation of the levels of alcohol sulfates and ethoxysulfates in marine sediments near wastewater discharge points along the coast of Tenerife Island.

Alcohol sulfates (AS) and alcohol ethoxysulfates (AES) are all High Production Volume and 'down-the-drain' chemicals used globally in detergent and personal care products, resulting in low levels ultimately released to the environment via wastewater treatment plant effluents. They have a strong affinity for sorption to sediments. Almost 50% of Tenerife Island surface area is environmentally protected. Therefore, determination of concentration levels of AS/AES in marine sediments near wastewater discharge points along the coast of the Island is of interest. These data were obtained after pressurized liquid extraction and liquid chromatography-tandem mass spectrometry analysis. Short chains of AES and especially of AS dominated the homologue distribution for AES. The Principal Components Analysis was used. The results showed that the sources of AS and AES were the same and that both compounds exhibit similar behavior. Three different patterns in the distribution for homologues and ethoxymers were found.

Validation of a GC-MS/MS method for simultaneous determination of 86 persistent organic pollutants in marine sediments by pressurized liquid extraction followed by stir bar sorptive extraction.

A multiresidue method for the analysis of 86 persistent pollutants in marine sediments at ultra-trace level has been developed and validated using pressurized liquid extraction (PLE) and stir-bar sorptive extraction (SBSE) coupled with thermal desorption and gas chromatography-triple quadrupole mass spectrometry (TD-GC-MS/MS QqQ). The compounds analyzed belong to various families such as polychlorinated biphenyls, polycyclic aromatic hydrocarbons, polybrominated diphenylethers, organophosphorus and organochlorine pesticides and other pesticides such as urons, and triazines. The analytes have very different polarities and log K(ow) values, which is an important parameter in the optimization of a SBSE method. Due to PLE high efficiency and throughput rates, along with the proven ability for multiresidue analysis and excellent sensitivity of SBSE, we present an efficient method. The limits of quantification obtained ranged from 0.014 to 1.0 ng g(-1), with detection limits below pg g(-1) levels. In order to validate the proposed methodology, quality parameters such as recovery, linearity and reproducibility were studied. Recoveries ranged from 63% to 119%, reproducibility (in terms of Relative Standard Deviation for ten determinations) was lower than 35% in all cases, and determination coefficients higher than 0.990 for all analytes. The main factors that affect PLE, SBSE and GC-MS/MS procedures were optimized. The method was applied to the analysis of nine marine sediments obtained from the nine main submarine wastewater discharge points (emissaries) presents along the coast of Tenerife Island (Canary Islands, Spain).

Analysis of arsenic, lead and cadmium in wines from the Canary Islands, Spain, by ICP/MS.

Because of their high toxicity, arsenic, lead and cadmium need to be quantified in food and beverages. For the first time, in this study the content of arsenic, lead and cadmium was investigated in 152 wine samples from the Canary Islands, Spain, belonging to eight Denominations of Origin (DO) and four islands by inductively coupled plasma mass spectrometry (ICP-MS). The ranges of concentration found were 0.58-8.45 microg l(-1) for arsenic, 0.20-1.73 microg l(-1) for cadmium and 3.89-159.5 microg l(-1) for lead, and the mean content was 3.13, 0.63 and 28.74 microg l(-1), respectively. None of the wines contained levels above the limits set by the International Office of Vine and Wine (OIV), and thus did not pose a health hazard. Significant differences in mean content of those elements between harvest, type of wine, islands and DO were observed.

Selenium and mercury concentrations in sweet and dry bottled wines from the Canary Islands, Spain.

The concentrations of selenium and mercury were determined by atomic absorption spectrophotometry in sweet and dry bottled wines from the Canary Islands, Spain. The concentrations of mercury ranged from 2.6 to 4.9 microg x l(-1) for sweet wines, and from 1.5 to 2.6 microg x l(-1) for dry wines, differences (p < 0.05) being observed according to the island of production and type of wine, but not with respect to vintage. The concentration of selenium varied between 1.0 and 2.0 microg x l(-1) for sweet wines, and between 0.6 and 1.6 microg x l(-1) for dry wines. Differences were found in the mean concentrations according to the type of wine. Dry wines produced in La Palma presented a higher (p < 0.05) mean content than those observed in the wines of El Hierro and Lanzarote.