Determination of parabens in environmental solid samples by ultrasonic-assisted extraction and liquid chromatography with triple quadrupole mass spectrometry.

Analysis of various p-hydroxybenzoic esters (methyl, ethyl, isopropyl, propyl, benzyl, and butylparaben) in environmental solid samples was carried out by sonication-assisted extraction in small columns (SAESC) followed by liquid chromatography with triple quadrupole mass spectrometry (MS/MS). Solid samples were placed in small glass columns and extraction performed assisted by sonication in two consecutive steps of 15 min using acetonitrile as extraction solvent. Sample extracts were evaporated under nitrogen stream to 1 ml and analysed by LC-MS/MS. Satisfactory recoveries were obtained ranging from 83% to 110% depending on the analyte. Good limits of quantification (LOQs), between 0.11 and 0.49 ng g(-1) were obtained for LC-MS/MS, making this technique suitable for the determination of parabens in environmental solid samples, particularly at trace level. The developed method was applied to the determination of target analytes in different types of soil and sediments, finding levels between LOD and 6.35 ng g(-1).

Determination of selected environmental contaminants in foraging honeybees.

Colony losses of honeybees have been of great concern in the last years. To explain these losses, several studies have been reported, and various factors, such as pathogens and pesticides, have been considered as possible causes. Nevertheless, organic contaminants, rather than pesticides, are continuously released to the environment, and can be intercepted by honeybees during foraging with the possible consequent damage. Azoles and organophosphorus esters have been selected in this work as environmental contaminants to be monitored in honeybees. A fast and robust method has been developed to determine these organic pollutants in honeybees. It is based on matrix solid phase dispersion (MSPD), which performs sample dispersion with extraction and clean up in the same step, followed by LC-ESI-MS/MS determination. Recoveries of the method varied between 73% and 119% and MQLs ranged from 0.8 to 4 ng g(-1). Honeybee samples from ten apiaries located in different regions were analyzed applying the developed method. Azole compounds were found at low levels, but not in all samples, while organophosphorus esters were found in most samples whatever location. Tris-(2-chloroisopropyl) phosphate, TCPP, and tributyl phosphate, TBP, were detected in all honeybees samples at levels higher than the rest of organophosphates analyzed.

Screening of environmental contaminants in honey bee wax comb using gas chromatography-high-resolution time-of-flight mass spectrometry.

This study reports an analytical approach intended to be used for investigation of non-targeted environmental contaminants and to characterize the organic pollution pattern of bee wax comb samples. The method comprises a generic extraction followed by detection with gas chromatography coupled to high-resolution time-of-flight mass spectrometry (GC-TOF-MS), operated in electron impact ionization (EI) mode. The screening approach for the investigation of non-targeted contaminants consisted of initial peak detection by deconvolution and matching the first-stage mass spectra EI-MS(1) with a nominal mass spectral library. To gain further confidence in the structural characterization of the contaminants under investigation, the molecular formula of representative ions (molecular ion when present in the EI spectrum) and, for at least other two fragment ions, was provided for those with an accurate mass scoring (mass error < 5 ppm). This methodology was applied for screening environmental contaminants in 50 samples of bee wax comb. This approach has allowed the tentative identification of some GC-amenable contaminants belonging to different chemical groups, among them, phthalates and polycyclic aromatic hydrocarbons (PAHs), along with residues of veterinary treatments used in apiculture.

Determination of cereal herbicide residues in environmental samples by gas chromatography.

Gas chromatographic analysis of cereal herbicide residues in water, soil, plant and air is reviewed. Herbicides widely used in spring and winter cereals, i.e., phenoxyacids, benzonitriles, ureas, triazines, dinitroanilines, chloroacetamides and thiocarbamates, are considered. The main procedures used in the residue analysis, extraction, clean-up, derivatization and gas chromatographic determination are summarized and discussed.

Influence of soil moisture on sorption and degradation of hexazinone and simazine in soil.

Sorption and degradation rates of hexazinone and simazine on soil were determined in a sandy loam soil incubated, during 44 days, at 25 degrees C with moisture contents ranging from 4% to 18%. Herbicide levels in soil solution were also measured, after extraction of this solution by a centrifugation method. All experiments were conducted with treated soil in plastic columns, and the results showed that this method is suitable for the simultaneous study of pesticide sorption and degradation in soil at different environmental conditions. In general, sorption of both herbicides was higher for aged herbicide residues compared to recently applied herbicides, and soil subjected to drying and rewetting cycles had the highest sorption values. K(f) values ranged from 0.5 to 1.2 for simazine and from 0.2 to 0.4 for hexazinone. Degradation rates increased with soil moisture content for both herbicides, and drying-rewetting of soil yielded degradation rates slower than that obtained at 10% soil moisture content. Hexazinone concentration in soil solution decreased with incubation time faster than simazine.

Uptake of perfluorinated compounds by plants grown in nutrient solution.

The uptake rates of three perfluorinated carboxylates and three perfluorinated sufonates by a grass (B diandrus) grown in nutrient solution at two different perfluorinated compounds (PFCs) concentrations were assessed. Grass can be ingested by grazing animals causing the PFCs to enter the food chain, which is a pathway of human exposure to these compounds. A rapid and miniaturized method was developed to determine PFCs in plants, based on a matrix solid-phase dispersion (MSPD) extraction procedure followed by quantitation by HPLC-MS/MS with an MQL in the range from 1 to 9 ng/g. An increase of PFCs levels in plant was observed along the exposure time. Differences in uptake for studied perfluorinated carboxylates were found, showing a decrease with carbon chain length (from 3027 to 1,167 ng/g at the end of assay), whereas no significant differences in absorption were obtained between perfluorinated sulfonates (about 1,700 ng/g). Initially, higher PFC transfer factors (ratio between concentration in plant and concentration in initial nutrient solution) were obtained for plants growing in the nutrient solution at the highest PFC concentration, but these factors became similar with time to plants exposed to the lowest concentration.