Biomedical subjects

Lennart Mathiasson

Publications and source records attributed to Lennart Mathiasson.

15 recordsLinked to original sources

PubMed2006

Optimisation of pressurised liquid extraction for the determination of p,p'-DDT and p,p'-DDE in aged contaminated Ethiopian soils.

The effectiveness of extracting p,p'-DDT and p,p'-DDE from aged contaminated soil samples by means of pressurized liquid extraction (PLE) was evaluated. Two soil samples, which were contaminated more than 10 years ago, were used in the investigation. The static extraction time was optimised and then validated against the total sum of target analytes obtained from multiple sequential extractions. The PLE results were also compared with Soxhlet extraction (SOX). PLE for 3x10 min at 100 degrees C was proven to be more exhaustive than SOX in the determination of p,p'-DDE from both soil samples. In the case of p,p'-DDT, PLE was found to be equally as exhaustive as SOX. Additionally, most of the previous PLE investigations used hazardous organic solvents such as n-hexane, toluene and dichloromethane mixed with acetone, whereas in this investigation the less toxic solvent combination n-heptane/acetone has been employed.

Chemical Fractionation↗

PubMed2006

Supercritical fluid extraction (SFE) for determination of metalworking fluid aerosols.

A common methodology for analyzing metalworking fluid (MWF) aerosols in workplace air is based on gravimetry before and after organic solvent extraction of the MWFs from a suitable collection filter. Because MWFs have different chemical and physical properties, various mixtures of organic solvents have been used to extract the MWFs from their collection device. An alternative to organic solvents, used in the work presented in this article, is the use of a supercritical fluid. The efficiency of supercritical fluid extraction (SFE) was investigated by weighing conditioned filters before and after extraction of samples spiked with MWFs at different concentrations using the American Society for Testing and Materials method. For three common straight oil MWFs spiked on filters, supercritical carbon dioxide gave recoveries of 92-101% with a low standard deviation (0.2-1.9%). For semisynthetic MWFs, carbon dioxide had to be mixed with methanol to obtain recoveries above 80%. With the optimized method using 7% methanol in carbon dioxide, the 10 investigated MWFs could be extracted in 30 min with a recovery of 90-98%. The amount of MWFs spiked on the filters varied between 0.10-1.65 mg. In Sweden, the limit value for MWFs is 1 mg/m3. Thus, our spike level is in the range of 10-200% of the limit value if sampling for 8 hours with 2 L/min. The use of SFE methodology results in small volume extracts (3 mL) with concentrations at such high levels that analysis of chemical components in the MWF can be carried out without further volume reduction.

Aerosols↗

PubMed2006

The performance of a natural treatment system for landfill leachate with special emphasis on the fate of organic pollutants.

A natural treatment system for the treatment of leachate was studied at Moskogen landfill in southern Sweden. This facility consists of three consecutive ponds and a soil-plant (SP)-system. A test area, receiving water from the third pond with the same hydraulic load as the SP-system, was used for estimation of the latter system. Quality parameters including biochemical oxygen demand, total organic carbon, ammonium, nitrate, orthophosphate, and total suspended solids along the treatment line were determined as well as soluble metals (Cu, Cd, Zn, Cr, Ni, and Pb). In addition a thorough investigation along the treatment line has also been performed concerning volatile organic compounds and semi-volatile organic compounds. Non-polar organic compounds were investigated using gas chromatography-mass spectrometry. Quantification was based on the assumption of equal response for the compounds found in comparison with the chosen marker substances. For polar, water-soluble compounds the measurements were restricted to phenolic compounds using high-performance liquid chromatography. Several different types of organic compounds were found in the raw leachate including aromatics, benzene-sulfonamides, biphenyls, naphthalene, organic phosphates, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phenols and phthalates. The treatment system efficiently reduced organic pollutants, heavy metals, and nitrogen/phosphorous compounds. Most metals and organic compounds in the leachate were already significantly reduced to a low level in the treatment ponds and ammonium-N was efficiently transformed to nitrate-N in the SP-system.

Chromatography, High Pressure Liquid↗

PubMed2006

Development of a combined solid-phase extraction-supercritical fluid extraction procedure for the determination of polychlorinated biphenyls in wastewater.

A combined solid-phase extraction (SPE)-supercritical fluid extraction (SFE) procedure was developed for the analysis of polychlorinated biphenyls (PCBs) in wastewater. The importance of cleaning and drying the filters and SPE-disks prior to eluting PCBs with SFE was studied, leading to improved recoveries for all congeners investigated. The average PCB recovery of the final procedure, at a concentration of 18 ng/L in reagent water, was 101% with relative standard deviations ranging from 1 to 5% for the different congeners. Spiked leachate to a final concentration of 4 ng/L was extracted directly after spiking, or after 24 h of spiking. An average recovery of 112% was obtained in the direct extraction of spiked leachate.

Journal Article↗

PubMed2005

Development of a pressurized liquid extraction and clean-up procedure for the determination of alpha-endosulfan, beta-endosulfan and endosulfan sulfate in aged contaminated Ethiopian soils.

Pressurized liquid extraction (PLE) was investigated for the extraction of two endosulfan isomers and their metabolite from two real contaminated soil samples. PLE for 3x10min at 100 degrees C was proven to be more exhaustive than Soxhlet extraction (SOX) in one soil sample. On the other soil sample investigated the method was found to be equally exhaustive as SOX. The use of hazardous organic solvents such as n-hexane, toluene, and diethyl ether has been avoided in PLE and clean-up. Instead less toxic solvents have been used both at the extraction step (acetone/n-heptane) and clean-up step (ethyl acetate/n-heptane). A column Florisil clean-up procedure that consumes relatively low solvent volumes has been optimized and applied to purify soil extracts. The developed analytical procedure was validated by applying it to a certified reference soil material (CRM811-050). A recovery of 103% total endosulfan residue was obtained versus certified values.

Chemical Fractionation↗

PubMed2005

Optimization of an analytical procedure for the determination of banned azo dyes in leather.

The possibility of improving an existing method, based on supercritical-fluid extraction (SFE) and microwave-assisted extraction (MAE), for the determination of banned azo dyes in leather has been studied. Thus, optimization of experimental conditions in different steps (degreasing, reduction, and extraction) of the analytical procedure was performed. The influence of different variables (reaction time, temperature, and concentration of reducing agent) on the reduction process was evaluated by use of a factorial design. It was found that the concentration of the reducing agent and the interaction between time and temperature were the most influential variables. Consequently, by applying a higher temperature, the reaction time could be halved. The use of acidified water as extraction solvent in MAE was also investigated. Usually 1 mol L(-1) HCl was superior to methanol and buffer in terms of extraction efficiency. In conclusion, the present method gave significantly higher recoveries in comparison with the original method. All dyes were determined indirectly by measuring their corresponding harmful amines, formed after reduction by use of sodium dithionite.

Journal Article↗

PubMed2005

Standard additio--a way of improving quantification of banned azo dyes in leather.

An analytical procedure based on supercritical-fluid extraction and microwave-assisted extraction was applied on six different real leather samples for the determination of banned azo dyes. Determination of the dyes was performed indirectly by measuring their corresponding harmful aromatic amines, formed after reduction. A comparative study between external standard calibration and standard addition using both the dyes as well as the corresponding amines showed that the latter quantification method provided the highest accuracy.

Journal Article↗

PubMed2005

Leachability testing of metallic wastes.

The performance of two tests, a batch test and a percolation test for the characterization of waste as suggested in the EU council decision 2003/33/EC was investigated. The tests were carried out on two solid waste streams from a metal recycling industry. The concentrations of heavy metals such as Cu, Zn and Pb were more than one order of magnitude lower than the proposed limit values. Generally, batch test values were equal or higher than percolation test values. With the proposed test procedures both materials could be considered as non-dangerous wastes. The test performance was also investigated using a leachant with higher ionic strength instead of demineralized water as prescribed. The results clearly show a significant increase in the concentration of some heavy metals. Total concentrations of phenolic compounds and polychlorinated biphenyls were less than 1 p.p.m. and 2 p.p.b., respectively. The precision of the batch and the percolation tests were on average 48 and 35%, respectively.

Conservation of Natural Resources↗

PubMed2004

Development of a solid-phase extraction method for the determination of polychlorinated biphenyls in water.

Polychlorinated biphenyls (PCBs) in water were extracted with a rebuilt extraction unit using 47 mm C18 solid-phase extraction (SPE) disks. Three types of disks (SPEC, ENVI and Empore) were investigated for the extraction of seven PCBs from 11 reagent water spiked at two concentration levels (20 and 1000 ng/l). The Empore disks produced the best analyte recoveries (91-107% with R.S.D. of 1-8%) at the low concentration level and displayed no leaking tendency. Empore disks were therefore considered superior to ENVI and SPEC disks for the conditions outlined in this work. The obtained extracts were dried and purified in an additional clean-up step using custom-made columns containing Florisil and Na2SO4. For water containing large amounts of organic matter, a pre-filtration was included. Final analysis was carried out on a dual-column GC-electron-capture detection system with on-column injection. The optimised extraction method, including clean-up, was less time-consuming and used less hazardous organic solvents than conventional liquid-liquid extraction (LLE) methods. Recoveries were 92-102% with R.S.D. of 3-8%.

Chromatography, Gas↗

PubMed2004

A combination of micro-porous membrane liquid-gas extraction and solid-phase trapping for ultra trace determination of benzene in urine.

A method was developed for the determination of benzene in urine. The sample was pumped through the donor channel of a membrane extraction unit with a micro-porous membrane, separating the donor channel from an identical acceptor channel purged with nitrogen. The analyte reached the acceptor channel by diffusion through the membrane and was then swept by the carrier to a solid sorbent tube, where it was trapped. The analyte was subsequently thermally desorbed and analyzed by gas chromatography (GC) with mass selective detection (MS). After optimization, the recovery was close to quantitative, or 95%. Purging the membrane unit with pure water in between the samples eliminated any memory effects. The linearity was good in the concentration range examined (20-4000 ng l(-1)), with a correlation coefficient of 0.9996. The repeatability at 50 ng l(-1) and 400 ng l(-1) was 1.4% and 1.2%, respectively. The limit of detection was 12 ng l(-1) and the limit of quantification 35 ng l(-1). This enables assessment of benzene exposures of occupationally exposed subjects, of smokers and the majority of the general population. The developed method can be easily automated.

Benzene↗

PubMed2004

Pressurized hot water extraction of insecticides from process dust--comparison with supercritical fluid extraction.

Pressurized hot liquid water and steam were used to investigate the possibilities of extracting insecticides (carbofuran, carbosulfan, and imidacloprid) from contaminated process dust remaining from seed-pellet production. Extraction temperature was the most important parameter in influencing the extraction efficiency and rate of extraction, while varying the pressure had no profound effect. A clean-up procedure of the water extracts using solid phase extraction (SPE) was found to be necessary prior to final analysis by high-performance liquid chromatography (HPLC). Quantitative extraction (compared to a validated organic solvent extraction method) of imidacloprid was obtained at temperatures of 100-150 degrees C within 30 min extraction time. Temperatures above 150 degrees C were required to extract carbofuran efficiently. The most non-polar analyte of the investigated compounds, carbosulfan, gave no detectable concentrations with pressurized hot water extraction (PHWE). One reason might be its low solubility in water, and when attempts are made to increase its solubility by increasing the temperature it may degrade to carbofuran. This can explain recovery values above 100% for carbofuran at higher temperatures. A comparison of the PHWE results and those obtained with supercritical fluid extraction (SFE) revealed that PHWE is advantageous for polar compounds, where the solubility of the analyte in water is high enough that lower temperatures can be used. For non-polar compounds carbon dioxide based extraction is preferred unless the target analyte is highly thermostable.

Journal Article↗

PubMed2003

Design of a reverse osmosis plant for leachate treatment aiming for safe disposal.

Leachate treatment is one of the major environmental issues faced by landfill owners. One promising method for reduction of pollutant discharge is reverse osmosis (RO). RO technology was tested at a pilot plant at Hedeskoga Landfill in southern Sweden. This landfill receives municipal solid waste (MSW) and industrial, commercial and institutional (IC&I) waste, and produces about 3000 m3/ha of leachate annually. Annual variations in the volume of leachate produced, estimated from changes in leachate electrical conductivity, were relatively small and should therefore have a minor effect on the main performance parameter of an RO plant, i.e., the achievable volume reduction. The volume reduction (V(permeate)/V(feed)) of polluted water achieved in batch experiments with 200-1000 litres of raw leachate was more than 80% (4MPa) and the remaining 20% was left as retentate. However, raw leachate caused severe fouling problems in a continuous flow run and after 24 hours, the flux had decreased to about 20% of the initial value. By pre-treating the leachate in a storage pond combined with a wetland, the situation was significantly improved and the decrease in membrane flux was only 0.2% per hour during a 200 hour run. The retention in terms of total solids and chemical oxygen demand was 90%, and for ammonia, it was 82%, at a volume reduction of 50%. The HELP-model was used for prediction of the water balance for the Hedeskoga landfill, with special focus on estimation of potential evapotranspiration. With different types of vegetation and a volume reduction of 75% in the RO plant, it was found possible to achieve safe disposal by irrigating 25% to 40% of the leachate-producing landfill area with pre-treated leachate. Pre-treatment with wetlands and nature based systems reduce the need of detergents for cleaning of the membranes and water only can be used. Short pre-treatment by aeration is not sufficient to bring leachate to a condition sustainable for RO-treatment. In that case, it was found necessary with alkaline-acid-alkaline treatment to restore the permeability. The total treatment cost for a full scale treatment plant at Hedeskoga was estimated to be approximately 30 SEK/m3, of which 25 is capital and 5 is operational costs. This can be compared to the total treatment costs for municipal sewage in Sweden, which is 8 SEK/m3.

Detergents↗

PubMed2002

On-line automated sample preparation for liquid chromatography using parallel supported liquid membrane extraction and microporous membrane liquid-liquid extraction.

An automated system was developed for analysis of non-polar and polar ionisable compounds at trace levels in natural water. Sample work-up was performed in a flow system using two parallel membrane extraction units. This system was connected on-line to a reversed-phase HPLC system for final determination. One of the membrane units was used for supported liquid membrane (SLM) extraction, which is suitable for ionisable or permanently charged compounds. The other unit was used for microporous membrane liquid-liquid extraction (MMLLE) suitable for uncharged compounds. The fungicide thiophanate methyl and its polar metabolites carbendazim and 2-aminobenzimidazole were used as model compounds. The whole system was controlled by means of four syringe pumps. While extracting one part of the sample using the SLM technique. the extract from the MMLLE extraction was analysed and vice versa. This gave a total analysis time of 63 min for each sample resulting in a sample throughput of 22 samples per 24 h.

Automation↗

PubMed2002

Harmful azo colorants in leather. Determination based on their cleavage and extraction of corresponding carcinogenic aromatic amines using modern extraction techniques.

This study concerns the possibilities of using microwave-assisted extraction (MAE) or supercritical fluid extraction (SFE) for detection of harmful azo colorants in leather. After degreasing of the leather sample with SFE there follows a reductive cleavage of the azo colorants to their corresponding aromatic amines in the MAE or SFE equipment. The aromatic amines are subsequently extracted using either MAE or SFE and then finally determined by liquid chromatography with diode-array detection. The results have been compared with recoveries obtained using the German DIN method 53316. This standard method, based on conventional solvent extraction, is used in several European countries. Overall much better recoveries were obtained using MAE or SFE. With both MAE and SFE the amine recoveries of spiked leather samples were generally above 50%. The average recoveries were 62% for MAE and 60% for SFE (solvent collection) compared to 24% with the DIN method. For genuine leather samples the recoveries decreased, especially for benzidine. In this case the average values for MAE, SFE and DIN were 54, 38 and 19%, respectively. The quantification limits in leather samples using MAE or SFE were below 1 mg/kg for all amines investigated. The within-laboratory precision was generally better than 10%, varying somewhat with the analyte considered. With the proposed methodology, the amount of hazardous organic solvents used could be decreased and the sample throughput increased with at least a factor of two with less manual handling compared to the DIN method.

Amines↗

PubMedDate not supplied

Determination of fat content and fatty acid composition in meat and meat products after supercritical fluid extraction.

Two different relatively simple, commercially available supercritical fluid extractors (SFE), Leco and Foss-Tecator, were tested for the determination of total fat content in meat and meat products. The fatty acid composition in meat and meat products was also determined after the Foss-Tecator extraction in an aliquot of the extract. Total fat was determined by weighing after the different extraction procedures and the fatty acid composition by gas chromatography after hydrolysis and methylation of the extract. The results for total fat content agreed well with results from a standard method of Schmid, Bondzynski, and Ratzlaff, which uses conventional solvent extraction. Fatty acid composition was compared with the Bligh and Dyer extraction, and showed good agreement. The average relative difference between SFE and Bligh and Dyer of all fatty acids in the sample was <3% for acids exceeding 0.5% of total fatty acid amount. The advantages of SFE over traditional methods are a much lower consumption of hazardous organic solvents and shorter extraction times. To obtain quantitative recoveries by SFE, ethanol was added to the extraction cells before extraction.

Animals↗