Kari Hartonen

Determination of brominated flame retardants in environmental samples

The last few decades have seen dramatic growth in the scale of production and use of brominated flame retardants (BFRs). Not surprisingly, the levels of these compounds in the environment have increased as well. Even though the acute toxicity of most BFRs seems to be fairly low, some have shown similar toxic effects to PCBs and polychlorinated dibenzo-p-dioxins and furans. Thus, BFRs are a potential hazard to the environment and their levels in the environment must be monitored. This article gives a brief overview of the analytical methodology used for the determination of BFRs in environmental samples and the levels of BFRs found in the samples.

Asymmetrical flow field-flow fractionation technique for separation and characterization of biopolymers and bioparticles

Field-flow fractionation (FFF) is one of the most versatile separation techniques in the field of analytical separation sciences, capable of separating macromolecules in the range 10³-10¹⁵ g mol⁻¹ and/or particles with 1 nm-100 μm in diameter. The most universal and most frequently used FFF technique, flow FFF, includes three types of techniques, namely symmetrical flow FFF, hollow fiber flow FFF, and asymmetrical flow FFF which is most established variant among them. This review provides a brief look at the theoretical background of analyte retention and separation efficiency in FFF, followed by a comprehensive overview of the current status of asymmetrical flow FFF with selected applications in the field of biopolymers and bioparticles.

Comparison of hydrodistillation and supercritical fluid extraction for the determination of essential oils in aromatic plants

Abstract Supercritical fluid extraction (SFE) and hydrodistillation were compared as methods to extract essential oils from savory, peppermint and dragonhead. Despite the high solubilities of essential oil components in supercritical CO2, the extraction rates were relatively slow with pure CO2 (ca. 80% recovery after 90 min). However, a 15-min static extraction with methylene chloride as modifier followed by a 15-min dynamic extraction with pure CO2 yielded high recoveries which agreed well with the results Of hydrodistillation performed for 4 h. Spike recovery studies demonstrated that compounds as volatile as monoterpenes can be quantitatively ( > 90%) collected off-line from the SFE effluent. SFE recovered some organic compounds from each of the samples that were not extracted by hydrodistillation, most notably C27, C29, C31, and C33 n-alkanes.

Extraction of iridoid glycosides and their determination by micellar electrokinetic capillary chromatography.

Several methods for the extraction of two iridoid glycosides, catalpol and aucubin, from the plant matrix (Veronica longifolia leaves) were compared. Pressurized hot water extraction and hot water extraction were the most efficient isolation techniques for both. Pressurized liquid extraction and maceration with various organic solvents were also tested. Relative to the amounts extracted with hot water, ethanol extracted only 22% of catalpol and 25% of aucubin and pressurized hot water extracted 83% of catalpol and 92% of aucubin. The lowest relative standard deviations, 22% for catalpol and 8% for aucubin, were achieved with hot water extraction (13 repetitions), and the highest relative standard deviations, 76% for catalpol and 73% for aucubin, with pressurized liquid extraction (five repetitions). A fast capillary electrophoretic method was developed for the quantitative determination of catalpol and aucubin.

Extraction of polychlorinated biphenyls with water under subcritical conditions

Abstract Supercritical fluid extraction is a fast and efficient method to extract all manner of organic compounds from a wide variety of solid sample matrices. Due to the marked change in its polarity with temperature, water is an interesting alternative to carbon dioxide as the extraction fluid. By merely adjusting the temperature, selectivity can be achieved for inorganic or organic compounds and for polar or non-polar organic compounds. Many organic compounds are sufficiently soluble to be extracted under subcritical conditions and, in this way, instrumental and other problems, such as the high corrosiveness of supercritical water, can be avoided. Instrumentation for sub- and supercritical water extraction was developed and modified in several ways with the aim of simplifying the procedure while maintaingng good recoveries. Good recoveries of polychlorinated biphenyls (PCBs) spiked into sea sand and of native PCBs in a real soil sample were achieved with liquid collection. Relative to Soxhlet extraction, recoveries were higher or similar when solid-phase and liquid collection were combined. With a solid-phase trap packed with Tenax, the recovery was usually more than 85% for spiked PCBs.

Extraction of clove using pressurized hot water

Subcritical water extraction was used to extract eugenol and eugenyl acetate from clove at various temperatures and pressures where water was in either the liquid or gas (steam) phase. Several solid phase materials were tested in order to quantitatively and selectively collect the analytes after the water extraction. Quantitative collection of eugenol and eugenyl acetate could be achieved using a C18 solid phase trap. The extraction kinetics with subcritical water was very fast at high temperatures (250°C and 300°C), giving a 100% recovery after 15 min for eugenol and eugenyl acetate, compared to extraction at 125°C, where the same recovery was achieved only after 80 min extraction. In addition, both eugenol and eugenyl acetate proved to be stable at the highest extraction temperature (300°C) used in this study. Copyright

Pressurised hot water extraction coupled on-line with liquid chromatography–gas chromatography for the determination of brominated flame retardants in sediment samples

Pressurised hot water extraction (PHWE) was coupled on-line with liquid chromatography-gas chromatography (LC-GC) to determine brominated flame retardants in sediment samples. After extraction with pressurised hot water the analytes were adsorbed in a solid-phase trap. The trap was dried with nitrogen and the analytes were eluted to the LC column, where the extract was cleaned, concentrated and fractionated before transfer to the GC system. The fraction containing the brominated flame retardants was transferred to the GC system via an on-column interface. The PHWE-LC-GC method was linear from 0.0125 to 2.5 microg with limits of detection in the range 0.70-1.41 ng/g and limits of quantification 6.16-12.33 ng/g.

Comprehensive two-dimensional gas chromatography in the analysis of urban aerosols.

Comprehensive two-dimensional gas chromatography utilising a semi-rotating cryogenic modulator was applied to the analysis of urban aerosols. Samples were collected onto glass fibre filters using a high-volume sampler in Helsinki, Finland. Sample preparation included extraction into n-hexane-acetone mixture and clean-up on silver-impregnated silica column. Analyses were performed with GC x GC-FID and GC x GC-QMS equipment. Linearity of the method was good with R2 values greater than 0.994 for all analytes. Polycyclic aromatic hydrocarbons (PAHs) and oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) were identified and quantified in urban particulates. PAH and oxy-PAH concentrations ranged from 0.5 to 5.5 ng/m3.

Pressurized hot water extraction coupled with supercritical water oxidation in remediation of sand and soil containing PAHs

Water is an alternative solvent and reaction medium compatible with green ideology. Extraction with pressurized hot water (PHW) and oxidation with supercritical water (SCW) are techniques that exploit the altered physico-chemical properties of heated and pressurized water for the treatment of solid and liquid wastes. On-line coupled pressurized hot water extraction (PHWE) and supercritical water oxidation (SCWO) equipment was constructed to extract polyaromatic hydrocarbons (PAHs) from sea sand and a real soil sample and to break down the compounds through oxidation with hydrogen peroxide. Overall, the best extraction recoveries were obtained at 300 °C with 20 min extraction time. The compounds with the highest molecular mass were the most difficult to extract. Compared with Soxhlet extraction, PHWE gave better recoveries, especially for the compounds with low molecular mass. The oxidation efficiencies (conversions of the PAHs) increased with oxidant concentration and reaction time. Conversions of compounds other than PAHs were good and total organic carbon was clearly decreased under the optimized conditions. Technically the equipment performed safely and effectively, and the PHWE-SCWO procedure gave good extraction recoveries and oxidation efficiencies.

Isolation of flavonoids from aspen knotwood by pressurized hot water extraction and comparison with other extraction techniques.

Pressurized hot water extraction (PHWE) conditions (time, temperature, pressure) were optimized for the extraction of naringenin and other major flavonoids (dihydrokaempferol, naringin) from knotwood of aspen. Extracts were analysed by GC-FID, GC-MS, HPLC-UV and HPLC-MS. The results were compared with those obtained by Soxhlet, ultrasonic extraction and reflux in methanol. Flavonoids were most efficiently extracted with PHWE at 150 degrees C and 220 bar with 35 min extraction time. Soxhlet with methanol gave slightly higher recoveries, but an extraction time of 48 h was required. Naringenin concentration was highest in knotwood (1.15% dry weight) and much lower in the sapwood. PHWE proved to be cheap, fast and effective for the isolation of biofunctional flavonoids from aspen knotwood, producing higher recoveries than 24 h Soxhlet extraction, sonication or 24 h reflux.