Accelerated Solvent Extraction System Research Articles

Extraction of Antioxidant Compounds from Eugenia uniflora L. Leaves by Energized Dispersive Guided (EDGE) System

The leaves of Pitanga (Eugenia uniflora L.) present recognized antioxidant potential that has practical applications in pharmaceuticals, food, perfume, agrochemical, and cosmetic industries. The Energized Dispersive Guided Extraction (EDGE) system, which combines dispersive solid-phase extraction with the Accelerated Solvent Extraction system, was employed in "combined mode" with extraction cycles to obtain antioxidant compounds from Pitanga leaves. The results showed that extraction cycles with different solvents produce similar extraction yields. At the same time, their ability to scavenge free DPPH radicals exhibited variations according to the polarity of the extraction solvent. Thus, acetone was the optimal solvent for extracting antioxidant compounds from E. uniflora leaves in the combined mode.

A modern purification by accelerated solvent extraction and centrifugal partition chromatography and biological evaluation of capsaicin from Capsicum chinense

A special alkaloid compound known as capsaicin, which can only be found in the fruit of the Capsicum plant, was isolated and tested for its anti-inflammatory activity. The purpose of this work is to establish a simple and quick approach for capsaicin purification utilizing centrifugal partition chromatography (CPC) as well as an effective method - accelerated solvent extraction (ASE), for extracting capsaicin from Capsicum chinense. After purification, capsaicin was validated by HPLC-DAD at 281 nm to be > 90% purity. The in vivo anti-inflammatory activity of the isolated capsaicin was also investigated, and the IC50 value of the capsaicin was determined to be 57.61 µg/mL. The current work emphasizes how an ASE and CPC system may combine to extract high-purity capsaicin from Capsicum chinense, which have the anti-inflammatory activity, as we evaluated in the experiment.

Development of extraction methodology for identification of extractive-compounds indexing natural durability of selected wood species

ABSTRACT This study is concerned with establishing a uniform experimental protocol for the determination of phenolic extractives, which play an essential role in the durability of the wood of selected species included in the field tests. European larch (Larix decidua), Norway spruce (Picea abies), Scots pine (Pinus sylvestris), European oak (Quercus sp.), sweet chestnut (Castanea sativa), and black locust (Robinia pseudoacacia) were included in the study. Extraction yield data were collected for extraction in a Soxhlet apparatus using common polar extraction solvents (ethanol, acetone, methanol, water) and for single static extraction cycles in accelerated solvent extraction (ASE). The suitability of the solvents and the appropriate extraction conditions were evaluated based on the results of gravimetric analysis of hydrophilic extractives, spectrophotometric analysis of total phenols, and chromatographic analysis using high-performance liquid chromatography. Extraction in the ASE system with methanol proved to be a quick and accurate way to prepare samples for chemical analysis of extractives of selected wood species. With the chemical monitoring of targeted phenolic extractives in wood subjected to leaching, we propose a novel protocol suitable also for for measuring the effects of weathering on the natural durability of wood in future studies.

Simultaneous Extraction of Four Antibiotic Compounds from Soil and Water Matrices

The incidence of antibiotic resistance is on the rise and becoming a major health concern. Analyzing the presence of antibiotic compounds in the environment is critical for determining the potential health effects for humans, animals, and ecosystems. For this study, methods were developed to simultaneously isolate and quantify four antibiotics important in human medicine (sulfamethoxazole—SMX, trimethoprim—TMP, lincomycin—LIN, and ofloxacin—OFL) in water and soil matrices. For water analysis, different solid phase extraction (SPE) cartridges (Oasis HLB plus and Phenomenex Strata-X) were compared. The Oasis HLB Plus SPE cartridge provided the highest and most consistent recoveries with 118 ± 5%, 86 ± 4%, 83 ± 5%, and 75 ± 1% for SMX, TMP, LIN, and OFL, respectively. For soil analysis, different pre-treatments (grinding and freeze-drying) and soil extraction methodologies (liquid-solid extraction and accelerated solvent extraction (ASE)) were compared. The ASE system resulted in the highest overall recoveries of SMX, TMP, LIN, and OFL with an optimal extracting solution of acetonitrile/water (v/v, 50:50, pH 2.8). When the soil was ground and freeze-dried, trimethoprim recovery increased and when soil was ground, but not freeze-dried, LIN and OFL recoveries increased, while sulfamethoxazole recoveries decreased when soil was ground and freeze-dried. Based on this research, matrix characteristics, especially pH, as well as the pKa’s and functional groups of the antibiotics need to be carefully considered when attempting to extract antibiotic compounds from a water or soil environment.

Application of solvent pH under pressurized conditions using accelerated solvent extraction and green solvents to extract phytonutrients from wild berries

Berry fruits are known as “superfoods” due to health benefits associated with the high content of bioactive compounds or phytonutrients. Organic extraction solvents are fundamentally volatile compounds acquired from non-renewable resources, i.e petroleum-based solvents are presumed to be harmful to both human health and the environment. Owing to the new emphasis on environmental and safety protections and the development of green chemistry, finding alternative solvents to replace the organic ones has recently become a major concern. Indeed, there is a great interest in the scientific community to develop a suitable green approach to allow the extraction and recovery of the bioactive phytonutrients from berry sources for applications in improving human health and nutrition. In this study, the phytonutrient composition of three popular wild berries: blueberry (Vaccinium angustifolium), partridgeberry (Vaccinium vitis-idaea L.) and Rosehipberry (Rosa canina), were evaluated following extraction using biphasic green solvents at pH 2.5, 7.0, and 11.5 under pressurized conditions using Accelerated Solvent Extraction (ASE) system. The total phenolic content and composition, antioxidant activity, vitamin and mineral content of the berry extracts were evaluated using Folin-Ciocalteu assay, Ferric Reducing Antioxidant Power Assay (FRAP), Ultra-High-pressure Liquid Chromatography-Mass Spectrometry (UHPLC-MS) and inductively coupled plasma-mass spectrometry (ICP-MS), respectively. The highest total antioxidant activity (p ≤ 0.05) and phenolic content were observed in rosehip berry followed by blueberry and partridgeberry in the hydroethanolic extracts at pH 11.5. Nevertheless, the highest extraction efficiency of total fat-soluble vitamins (FSV) and total B vitamins were also observed in the hydroethanolic extract at pH 11.5. Both in rosehipberry and partridgeberry the highest vitamin C content was observed in hydroethanolic extract at pH 11.5, whereas in blueberry it was observed in the pH 2.5 hydroethanolic extract. In the present study, results demonstrated that using the green solvent system (hydroethanolic, 70:30 v/v) at alkaline pH (11.5) as a pressurized fluid in the ASE system provided significant recovery of phytonutrients from wild berries. This green environmentally friendly system of extraction could represent a suitable alternative for the preparation of food grade or green solvent-based extracts for applications in the food and nutraceutical industry.

Determination of 32 polychlorinated biphenyls in aquatic products by gas chromatography-high-resolution mass spectrometry with accelerated solvent extraction-purification simultaneously coupled to isotope internal standard method

Gas chromatography (GC)-high-resolution mass spectrometry (HRMS) with accelerated solvent extraction (ASE)-purification simultaneously coupled to the isotope internal standard method is proposed for the determination of 32 polychlorinated biphenyls (PCBs) in aquatic products. Synchronous purification was achieved by adding 2 g of anhydrous sodium sulfate, 1 g of Cleanert Florisil, and 50 g of neutral alumina as the adsorbent to the ASE system. The PCBs were extracted from aquatic product samples using a dichloromethane-n-hexane (1:1, v/v) mixture at 100 ℃ with two extraction cycles. The extracting solution was purified twice with 0.5 mL concentrated sulfuric acid. After concentration to a constant volume, the target compounds were detected by GC-HRMS and quantified by the isotope internal standard method. Under the optimized conditions, the relative standard deviations (RSDs) of the mean relative response factor (RRF) for the 32 PCBs in the range of 0.1-20 μg/L were less than 15%. The limits of quantification were 0.3-1.9 ng/kg. At three spiked levels (5, 20, and 50 ng/kg) in grass carp and sea bass, the recoveries of the 32 PCBs were between 71.9% and 119.0%, with the RSDs varying from 3.5% to 19.6%. This method effectively reduces the matrix interference and shows high sensitivity, good reproducibility, and stable recovery, thus proving useful for the detection of PCBs in aquatic products.

Optimization of accelerated solvent extraction (ASE) of silver fir wood (Abies alba Mill.)

Qualitative and quantitative analysis of wood plant extractives depend on the efficiency of the extraction method used. The aim of this study was the application of the accelerated solvent extraction system ASE 350 to obtain hydrophilic extracts form silver fir wood (Abies alba Mill.) and optimization of the extraction protocol. Silver fir trees originated from Kočevska Reka. Dissected and milled samples of sapwood, heartwood and knots were extracted with the ASE 350 with water, ethanol (95 % aq), acetone (95 % aq) and ethyl acetate. The number of extraction cycles was determined. Analysis of extracts was done by UV/Vis spectrophotometry and HPLC. The most effective solvent for the extraction of phenolic components from heartwood was ethanol (95 % aq), in the case of sapwood water and acetone (95 % aq) in the case of knotwood. Only two 5-minute extraction cycles were required for sufficient extraction yield when using ASE 350 at 100 °C and 103.42 bar.

Enhanced Glucose Uptake in Human Liver Cells and Inhibition of Carbohydrate Hydrolyzing Enzymes by Nordic Berry Extracts

A Western lifestyle with low physical activity and a diet rich in sugar, fat and processed food contribute to higher incidences of diabetes and obesity. Enhanced glucose uptake in human liver cells was observed after treatment with phenolic extracts from different Nordic berries. All berry extracts showed higher inhibition against α-amylase and α-glucosidase than the anti-diabetic agent acarbose. Total phenolic content and phenolic profiles in addition to antioxidant activities, were also investigated. The berries were extracted with 80% methanol on an accelerated solvent extraction system (ASE) and then purified by C-18 solid phase extraction (SPE). Among the ASE methanol extracts, black chokeberry, crowberry and elderberry extracts showed high stimulation of glucose uptake in HepG2 cells and also considerable inhibitory effect towards carbohydrate hydrolyzing enzymes. SPE extracts with higher concentrations of phenolics, resulted in increased glucose uptake and enhanced inhibition of α-amylase and α-glucosidase compared to the ASE extracts. Crowberry and cloudberry were the most potent 15-lipoxygenase inhibitors, while bog whortleberry and lingonberry were the most active xanthine oxidase inhibitors. These results increase the value of these berries as a component of a healthy Nordic diet and have a potential benefit against diabetes.

How to Plant Apple Trees to Reduce Replant Disease in Apple Orchard: A Study on the Phenolic Acid of the Replanted Apple Orchard.

Apple replant disease (ARD) is an important problem in the production of apple. The phenolic acid is one of the causes of ARD. How phenolic acid affects the ARD was not well known. In this study, we analyzed the type, concentration and annual dynamic variation of phenolic acid in soil from three replanted apple orchards using an accelerated solvent extraction system with high performance liquid chromatography (ASE-HPLC). We found that the type and concentration of phenolic acid were significantly differed among different seasons, different sampling positions and different soil layers. Major types of phenolic acid in three replanted apple orchards were phlorizin, benzoic acid and vanillic aldehyde. The concentration of phenolic acid was highest in the soil of the previous tree holes and it was increased from the spring to autumn. Moreover, phenolic acid was primarily distributed in 30–60 cm soil layer in the autumn, while it was most abundant in 0–30 cm soil layer in the spring. Our results suggest that phlorizin, benzoic acid and vanillic aldehyde may be the key phenolic acid that brought about ARD in the replanted apple orchard.

Complement fixing polysaccharides from Terminalia macroptera root bark, stem bark and leaves.

The root bark, stem bark and leaves of Terminalia macroptera were sequentially extracted with ethanol, 50% ethanol-water, and 50 °C and 100 °C water using an accelerated solvent extractor. Ten bioactive purified polysaccharide fractions were obtained from those crude extracts after anion exchange chromatography and gel filtration. The polysaccharides and their native extracts were characterized with respect to molecular weight, chemical compositions and effects in the complement assay. The chemical compositions showed that the polysaccharides are of pectic nature. The results indicated that there was no great difference of the complement fixation activities in the crude extracts from the different plant parts when extracting with the accelerated solvent extraction system. The purified polysaccharide fractions 100WTSBH-I-I and 100WTRBH-I-I isolated from the 100 °C water extracts of stem and root bark respectively, showed the highest complement fixation activities. These two fractions have rhamnogalacturonan type I backbone, but only 100WTSBH-I-I contains side chains of both arabinogalactan type I and II. Based on the yield and activities of the fractions studied those from the root bark gave highest results, followed by those from leaves and stem bark. But in total, all plant materials are good sources for fractions containing bioactive polysaccharides.

Determination of polybrominated diphenyl ethers and polychlorinated biphenyls in fishery and aquaculture products using sequential solid phase extraction and large volume injection gas chromatography/tandem mass spectrometry

A new method was developed to determine polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in fishery and aquaculture products. Samples were extracted by an accelerated solvent extraction system and cleaned up by sequential solid phase extraction (SPE) including dispersive SPE (D-SPE) and tandem SPE. PBDEs and PCBs were analyzed by a large-volume injection gas chromatography triple quadrupole mass spectrometry (LVI-GC-QqQ-MS/MS). Good linearity (R(2)≥0.9958) was achieved. Method detection limits (MDLs) were 0.16-3.3pgg(-1) (wet weight, ww) for PBDEs and 0.13-0.97pgg(-1)ww for PCBs. Mean recoveries were 60-140% with relative standard deviations (RSDs) of less than 20% in weever fish, scallop and shrimp samples spiked at a lower level of 13-31pgg(-1)ww and a higher level of 50-125pgg(-1)ww. Certified reference materials were analyzed with acceptable results. The method reduced solvent consumption, analytical time and labor, and is suitable for the routine analysis of PBDEs and PCBs in fishery and aquaculture products.

Pharmaceutical residues in tidal surface sediments of three rivers in southeastern China at detectable and measurable levels

Pharmaceutical compounds were increasingly detected in environmental matrices but little is known whether these compounds would transport to coastal zones via watersheds. Three typical tidal rivers in southeastern China were selected and 15 surface sediment samples (0-10 cm) were collected along a 50-km tidal section of each river. Surface sediment samples were frozen-drying and then extracted for pharmaceutical compounds by an accelerated solvent extraction system. The pharmaceutical compounds in extracts were scanned using a high-performance liquid chromatography/tandern mass spectrometry (HPLC-MS/MS). Three hundred and thirty compounds from nine pharmaceutical groups were detected with signal-to-noise above three (detectable level) in the surface sediments, of which 186 compounds were with a signal-to-noise above ten (measurable level). Of all, 291 and 80 compounds were detectable and measurable in all the three rivers, respectively. The Jiulong River showed a high load of pharmaceutical compounds in surface sediment than other two rivers. Of the nine pharmaceutical groups, the antihistamines and detoxification group and anti-infective drug group contributed five dominant compounds in the surface sediments in all the three rivers. Natures of pharmaceutical compounds rather than the sediment properties (pH, EC, and total carbon content) might influence their residues. The incredible number and intensity of pharmaceutical residues were detected in tidal surface sediments of the three rivers indicating that the pharmaceutical contamination should be strongly considered in China. Source identification and eco-toxicity assessment should be taken into account in the future study. Therapeutic medicine managements need to be strictly improved at a watershed scale to reduce loads of pharmaceuticals into aquatic ecosystems.

Analysis of toxaphene and its eight congeners in sediment and fish tissue by gas chromatography-negative ion mass spectrometry

Toxaphene quantification incorporating gas chromatography/negative chemical ionization mass spectrometry (GC/NCI-MS) offers improved sensitivity and specificity. The U. S. Environmental Protection Agency (USEPA) recently released a GC/NCI-MS method (Method 8276) for the measurement of technical toxaphene and eight specific congeners (Hx-Sed, Hp-Sed, P26, P41, P40, P44, P50 and P62). However, there is still lack of a practical and complete analytical method including sample extraction, clean up, instrumental analysis, and data analysis. The goal of this work was to develop a ready-to-use method for the quantification of total toxaphene and the eight congeners. Sediment and salmon fish tissue were selected as sample matrices and extracted with methylene chloride using an accelerated solvent extraction system. The sample extracts were cleaned up with active copper powder or gel permeation chromatography, and finally silica/alumina combination column. Separation was performed on a DB-XLB column. GC/NCI-MS was operated under selected ion monitoring mode with an identical set of confirmation and quantitation ions for total toxaphene and the eight congeners. Oxygen reaction of polychlorinated biphenyls (PCB) was monitored by PCB204, an internal calibration standard, and the reaction level was kept below 1%. Average relative response factors were used in quantitation. Quantitation of total toxaphene employed the sum of all detectable (S/N > or = 3) 6-C1 to 10-Cl homolog peak areas, while the individual congeners were quantified followed the standard procedures for single analytes. Multi-point calibration solutions ranged from 0. 5 (5 for P62) to 500 microg/L for the individual congeners, and 50 to 500 microg/L for technical toxaphene, with the lowest calibration levels as lower limits of quantitation. Average congener recovery was (90.8 +/- 17.4)% (n =10) in spiked sediment with relative standard deviations of 5.4% - 12.8% (n =10), underscoring an excellently accurate and precise method. The method was applied to analyze sediment and fish tissue sample.

Extraction, isolation, and purification of analytes from samples of marine origin – A multivariate task

The development of a multivariate study for a quantitative analysis of six different polybrominated diphenyl ethers (PBDEs) in tissue of Atlantic Salmo salar L. is reported. An extraction, isolation, and purification process based on an accelerated solvent extraction system was designed, investigated, and optimized by means of statistical experimental design and multivariate data analysis and regression. An accompanying gas chromatography–mass spectrometry analytical method was developed for the identification and quantification of the analytes, BDE 28, BDE 47, BDE 99, BDE 100, BDE 153, and BDE 154. These PBDEs have been used in commercial blends that were used as flame-retardants for a variety of materials, including electronic devices, synthetic polymers and textiles. The present study revealed that an extracting solvent mixture composed of hexane and CH2Cl2 (10:90) provided excellent recoveries of all of the six PBDEs studied herein. A somewhat lower polarity in the extracting solvent, hexane and CH2Cl2 (40:60) decreased the analyte %-recoveries, which still remain acceptable and satisfactory. The study demonstrates the necessity to perform an intimately investigation of the extraction and purification process in order to achieve quantitative isolation of the analytes from the specific matrix.

ANALYSIS OF ENVIRONMENTAL TOXIC SUBSTANCES IN ELECTRICAL AND ELECTRONIC PRODUCTS BY ULTRA HIGH PERFORMANCE LIQUID CHROMATOGRAPHY WITH TANDEM TRIPLE QUADRUPOLE MASS SPECTROMETRY AND ACCELERATED SOLVENT EXTRACTION

Bisphenol A, tetrabromobisphenol A, nonylphenol, and hexabromocyclododecane are common environmental toxic substances in electrical and electronic products. BPA and NP are defined as endocrine disrupting chemicals that have estrogenic effects, while TBBP-A and HBCD stereoisomers (α-, β-, γ-) are the most widely used brominated flame retardants besides polybrominated diphenyl ethers (PBDEs). In this study, a method by ultra-high performance liquid chromatography with tandem triple quadrupole mass spectrometry (UHPLC-ESI MS/MS) and accelerated solvent extraction has been developed for the simultaneous determination of these four compounds. UHPLC-ESI MS/MS parameters as well as accelerated solvent extraction parameters were optimized. Samples were extracted with 1:1 methanol:toluene (V/V) using an ASE 350 accelerated solvent extraction system and were injected into the UHPLC-ESI MS/MS system. The analysis could be rapidly achieved within 8 min and the three stereoisomers of HBCD could be baseline separated. Good linearities were obtained for all analytes (the correlation coefficients were above 0.99) in the range of 2 µg L−1–1000 µg L−1, with the detection limits 0.25 µg L−1–1.5 µg L−1 and quantification limits 1.0 µg L−1–5.0 µg L−1. The proposed method was applied to the analysis of six samples and the recoveries of all the analytes satisfactorily rangd from 88.7% to 105.5%.

Subcritical water extraction for the remediation of phthalate ester-contaminated soil

Subcritical water has been used as an environment-friendly extraction fluid for many classes of organic compounds. It was used for the removal of phthalate esters (PEs), such as di-methyl phthalate, DMP; di-ethyl phthalate, DEP; di-iso-propyl phthalate, DIPP; di-n-butyl phthalate, DBP; benzyl butyl phthalate, BBP; di-n-pentyl phthalate, DpentP; di-n-hexyl phthalate, DHXP; di-heptyl phthalate, DheptP; di-2-ethylhexyl phthalate, DEHP; di-n-nonyl phthalate, DNP; di-n-octyl phthalate, DOP; di-n-decyl phthalate, DDP, in soil samples under the optimum condition of 250 °C and 10 MPa in our study. The soil samples cleaned with subcritical water were extracted by homemade accelerated solvent extraction system (ASE) and analyzed by HPLC–UV to check for soil remediation efficiency. Three types of soil collected at different sites in Taiwan have been tested. Although at higher PEs concentration levels, the modification of treatments may be necessary for satisfactory removal of the contaminants, soil samples of different PEs levels treated with subcritical water extraction (SCWE) were analyzed and the results indicated removal efficiency ranges of 80–90% for PEs spiked in soil samples. Soil samples contaminated with native DEHP were treated and gave comparable recovery efficiencies. Our results indicate that the applications of subcritical water as soil remediation for removal of PEs contaminant are feasible.

Pigments in Avocado Tissue and Oil

Pigments are important contributors to the appearance and healthful properties of both avocado fruits and the oils extracted from these fruits. This study determined carotenoid and chlorophyll pigment concentrations in the skin and three sections of the flesh (outer dark green, middle pale green, and inner yellow flesh-nearest the seed) and anthocyanin concentrations in the skin of Hass avocado during ripening at 20 degrees C. Pigments were extracted from frozen tissue with acetone and measured using high-performance liquid chromatography. Pigments were also measured in the oil extracted from freeze-dried tissue sections by an accelerated solvent extraction system using hexane. Carotenoids and chlorophylls identified in the skin, flesh, and oil were lutein, alpha-carotene, beta-carotene, neoxanthin, violaxanthin, zeaxanthin, antheraxanthin, chlorophylls a and b, and pheophytins a and b with the highest concentrations of all pigments in the skin. Chlorophyllides a and b were identified in the skin and flesh tissues only. As the fruit ripened and softened, the skin changed from green to purple/black, corresponding to changes in skin hue angle, and a concomitant increase in cyanidin 3-O-glucoside and the loss of chlorophyllide a. In flesh tissue, chroma and lightness values decreased with ripening, with no changes in hue angle. The levels of carotenoids and chlorophylls did not change significantly during ripening. As fruit ripened, the total chlorophyll level in the oil from the flesh sections remained constant but declined in the oil extracted from the skin.

Detection of 2-Alkylcyclobutanones in Irradiated Meat, Poultry and Egg after Cooking

2-Alkylcyclobutanones in irradiated and cooked meats, poultry and egg were analyzed to detect the irradiation history of those samples prior to cooking. They were extracted using an accelerated solvent extraction system (ASE), and determined by gas chromatography with mass spectrometry (GC/MS). Irradiated beef, chicken and egg were browned and the irradiated beef and egg were boiled. The irradiated chicken was fried and a pancake was made with the irradiated egg. Radiolytic compounds of 2-dodecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutane (2-TCB) were detected in all the cooked samples when the raw samples were irradiated with 3-6.5 kGy. Both 2-DCB and 2-TCB were similarly stable in the samples with conventional cooking, which resulted in a temperature less than 100°C inside the samples, whereas they were destroyed when heated to over 200°C. The food samples did not show serious interferences on GC/MS chromatograms due to cooking. The results conclude that the analysis of 2-DCB and 2-TCB in the cooked samples would be a reliable indicator to detect the irradiation history of raw meats, poultry and egg.

Analysis of 2-Alkylcyclobutanones with Accelerated Solvent Extraction To Detect Irradiated Meat and Fish

A new analytical procedure has been developed to analyze 2-alkylcyclobutanones to detect gamma-ray-irradiated fat-containing foodstuffs. Samples were extracted with an accelerated solvent extraction system via hot and pressurized ethyl acetate in cells. A large amount of fat in the extract was precipitated and removed with filtration by standing at -20 degrees C after the addition of acetonitrile. The extract was further cleaned with a 1 g silica gel mini column, and the radiolytic compounds of 2-docecylcyclobutanone (2-DCB) and 2-tetradecylcyclobutanone (2-TCB) were determined with gas chromatography with mass spectrometry (GC/MS). Sample preparation time before GC/MS was 7-8 h. At first, the procedure was evaluated with a recovery test in eight samples spiked with 2-DCB and 2-TCB at 20 ng/g, resulting in 70-105% recoveries with mostly less than 10% relative standard deviations. The procedure was further evaluated with beef, pork, chicken, and salmon samples irradiated with gamma-rays from 0.7 to 7.0 kGy at -19 degrees C. Both 2-DCB and 2-TCB in most samples were detected with good dose-response relations at all doses, while salmon was detected more than 2 kGy irradiation. The amounts of 2-alkylcyclobutanones produced reflected precursor fatty acids levels in samples, especially for the combination of 2-TCB and stearic acid. The results indicated that the production rate of 2-TCB to stearic acid was more obvious than that of 2-DCB to palmitic acid in frozen samples with gamma-ray irradiation.

Accelerated solvent extraction (ASE) of environmental organic compounds in soils using a modified supercritical fluid extractor

Accelerated solvent extraction (ASE) has been applied to the quantitative extraction of a selected list of semi-volatiles, which include polycyclic aromatic hydrocarbons (PAHs), phenols, polychlorinated biphenyls (PCBs) and total petroleum hydrocarbons. Two conventional supercritical fluid extraction (SFE) systems, the Suprex Prep Master and SFE/50 systems have been modified to function as ASE systems. Using solvent instead of supercritical fluid, extraction in an enclosed system proceeded under high pressure and temperature. Parameters such as extraction temperature and effect of modifiers were investigated. Although limited by a 150 °C maximum oven temperature, effective extraction could be carried out in less than 25 min for all the compounds studied. The technique was applied to a variety of real matrices contaminated with hydrocarbons, PAHs and phenols. Validations of the technique were performed using standard reference materials. Recoveries for these matrices were good (>75%) and precision (R.S.D.) was generally less than 10%. Primarily a rapid field extraction technique, comparison with other rapid extraction such as sonication and microwave assisted extraction (MAP™) were made. Recoveries were found to be comparable to MAP™ and superior to sonication. On the present ASE system, only sequential extraction can be carried out but given the rapid nature of the process, about 15 samples can be carried out in a working day.