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1.
Mageshni Reddy Roshila Moodley Sreekanth B. Jonnalagadda 《Journal of environmental science and health. Part. B》2013,48(6):529-537
Interest in vegetable oil extracted from idioblast cells of avocado fruit is growing. In this study, five extraction methods to produce avocado oil have been compared: traditional solvent extraction using a Soxhlet or ultrasound, Soxhlet extraction combined with microwave or ultra-turrax treatment and supercritical fluid extraction (SFE). Traditional Soxhlet extraction produced the most reproducible results, 64.76 ± 0.24 g oil/100 g dry weight (DW) and 63.67 ± 0.20 g oil/100 g DW for Hass and Fuerte varieties, respectively. Microwave extraction gave the highest yield of oil (69.94%) from the Hass variety. Oils from microwave extraction had the highest fatty acid content; oils from SFE had wider range of fatty acids. Oils from Fuerte variety had a higher monounsaturated: saturated FA ratio (3.45–3.70). SFE and microwave extraction produced the best quality oil, better than traditional Soxhlet extraction, with the least amount of oxidizing metals present. 相似文献
2.
Comparison of supercritical fluid extraction and Soxhlet extraction for the determination of PCBs in seaweed samples 总被引:1,自引:0,他引:1
The efficiency of supercritical fluid extraction for the determination of 12 polychlorinated biphenyls from algae samples is compared to Soxhlet extraction. Analytical detection limits for the individual congeners ranged from 0.62 microgl(-1) to 19 microgl(-1). Recovery was tested for both methods using standard addition procedure. At maximum spike level of concentration, the mean recoveries were not significantly different (P>0.05) of all PCBs studied, with the exception of PCBs 28, 52, 77 and 169. Method precision for Soxhlet extraction (< or =3.9%) was slightly better than for SFE (< or =9.2%). Although both methods yield comparable results, SFE offers the advantage of detecting all PCBs studied at lower concentrations, reducing extraction time, and reducing the amount of solvents needed. The optimized methods were applied to the analysis of three real seaweed samples, except for PCB101 the concentrations of all PCBs were low or below the detection limits. The levels of PCB101 found in sample 1 were 6.6+/-0.54 ng g(-1) d.w., in sample 2 the levels were 8.2+/-0.86 ng g(-1) d.w. and in sample 3 they were 7.7+/-0.08 ng g(-1) d.w. 相似文献
3.
Analysis of polycyclic aromatic hydrocarbons in sediment reference materials by microwave-assisted extraction 总被引:3,自引:0,他引:3
The microwave-assisted extraction (MAE) of polycyclic aromatic hydrocarbons (PAHs) from harbor sediment reference material EC-1, marine sediment reference material HS-2 and PAH-spiked river bed soil was conducted. The extraction conditions for EC-1 were carried out at 70 degrees C and 100 degrees C under pressure in closed vessels with cyclohexane acetone (1:1), cyclohexane-water (3:1), hexane acetone (1:1), and hexane-water (3:1) for 10 min. A comparison between MAE and a 16-h Soxhlet extraction (SX) method showed that both techniques gave comparable results with certified values. MAE has advantages over the currently used Soxhlet technique due to a faster extraction time and lower quantity of solvent used. The consumption of organic solvent of the microwave method was less than one-tenth compared to Soxhlet. 相似文献
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Characterization of polycyclic aromatic hydrocarbons (PAHs) on lime spray dryer (LSD) ash using different extraction methods 总被引:6,自引:0,他引:6
In this study, traditional Soxhlet, automatic Soxhlet and ultrasonic extraction techniques were employed to determine the speciation and concentration of polycyclic aromatic hydrocarbons (PAHs) on lime spray dryer (LSD) ash samples collected from the baghouse of a spreader stoker boiler. To test the efficiencies of different extraction methods, LSD ash samples were doped with a mixture of 16 US EPA specified PAHs to measure the matrix spike recoveries. The results showed that the spike recoveries of PAHs were different using these three extraction methods with dichloromethane (DCM) as the solvent. Traditional Soxhlet extraction achieved slightly higher recoveries than automatic Soxhlet and ultrasonic extraction. Different solvents including toluene, DCM:acetone (1:1 V/V) and hexane:acetone (1:1 V/V) were further examined to optimize the recovery using ultrasonic extraction. Toluene achieved the highest spike recoveries of PAHs at a spike level of 10 microg kg(-1). When the spike level was increased to 50 microg kg(-1), the spike recoveries of PAHs also correspondingly increased. Although the type and concentration of PAHs detected on LSD ash samples by different extraction methods varied, the concentration of each detected PAH was consistently low, at microg kg(-1) levels. 相似文献
6.
As part of an evaluation of focused microwave-assisted extraction (FMAE) using an open-vessel system, the effects of matrix, moisture content, ageing, and solvent have been studied on the extraction efficiency of polycyclic aromatic hydrocarbons (PAHs) from spiked soils. PAHs were spiked onto three different uncontaminated air dried and originally wet soil matrices with 1- and 20-day ageing periods. Solvents used were hexane–acetone (1:1), cyclohexane–acetone (1:1) and dichloromethane. FMAE only required a small amount of solvent (20 ml) and short extraction time (10 min) in the open cell under 90 W of microwave power. The results revealed that the extraction efficiency strongly depends on the nature of soil matrix; moisture content may enhance the recoveries of PAHs for many cases; and, the influence of the type of solvent is not significant. A comparison between microwave extraction and 16-h Soxhlet extraction has been made on spiked soils. It evidenced that the microwave method under ambient pressure is a suitable alternative to Soxhlet method for the analysis of PAHs in soils. For the evaluation of the developed FMAE method, three reference materials were used. The PAHs recovered from three reference materials were in a good agreement with reference values. 相似文献
7.
Arditsoglou A Terzi E Kalaitzoglou M Samara C 《Environmental science and pollution research international》2003,10(6):354-356
The recovery of polycyclic aromatic hydrocarbons (PAHs) from lignite coal burnt in Greek power stations and the fly ash produced is examined comparatively using Soxhlet, ultrasonic and accelerated solvent extraction procedures with various organic solvents. Soxhlet using toluene/methanol mixture and accelerated solvent extraction/toluene were found to be the most efficient methods for fly ash PAHs, yielding average recoveries of about 80%. The accelerated solvent extraction/toluene procedure was superior for lignite PAHs, yielding 96% average recovery, whereas ultrasonic and Soxhlet extraction yielded relatively lower recoveries (75% and 67%, respectively). 相似文献
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Three toxaphene congeners have been determined in salmon from the Swedish coastal environment using both supercritical fluid (SFE) and the traditional liquid/liquid extractions. The levels obtained using a modifier-free SFE technique, followed by group separation on a silica gel column, were by far much lower than concentrations obtained by SFE with a modifier or liquid/liquid extraction. The mean concentrations on fresh weight basis using a liquid/liquid extraction technique were 5.87, 8.70 and 1.59 microg/kg for CHBs 26, 50 and 62, respectively. There was a plausible relationship between the various fishing sites and the toxaphene levels. 相似文献
10.
Conclusion Independent losses of internal standard by evaporation and/or sorption will increase both absolute and random errors for the
native analyte. Thus, the internal standard should only be used for compensation of losses, variations and irregularities
in the clean-up, dilution, transfer and instrument. This is achieved by addition of internal standard to the eluent after
extraction, or avoiding direct contact between internal standards and suspected active matrices. The analytical results will
then not guarantee a correct quantification of the true analyte concentration on the matrix, only maximise the precision of
measurement of extracted analyte. In Soxhlet extraction, the internal standard can be added to the solvent reservoir. In supercritical
fluid extraction (SFE), the internal standard might be added to an aliquot of reversed phase silica (C-8, C-18) located after
the sample in the fluid direction. 相似文献
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The aim of this study was to test the hypothesis about physical factors causing a significant decrease of polycyclic aromatic hydrocarbon (PAH) compounds in foodstuffs. For this purpose, extraction of 16 PAHs (prioritised by EPA) from selected foodstuffs (rapeseed oil and sunflower oil) was carried out. The changes in PAH content in oils exposed to selected physical factors (UV radiation, temperature and time) were observed. Oils under study were exposed to two types of UV radiation: direct and indirect (through a glass plate). In both experiments, a reduction of 16 PAHs in oils was recorded but in the latter a PAH reduction was not as high. In another experiment, the temperature of oils was raised to 40, 100 and 200°C. As a result, the content of PAHs has decreased significantly. In both cases, exposure to UV radiation and high temperature resulted in the reduction of PAHs, it was strongly correlated with the duration of experiments. The results showed relatively low contamination of oil with PAHs. Only for rapeseed oil, the level of said contamination was substantially higher than laid down limits. 相似文献
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利用索氏提取一减量法、减量法和自行开发的高效抽提法,对一系列已知组成的含油污泥进行了油、水含量的测定。测定结果表明,高效抽提法在油、水含量的测定精度方面优于其他2种方法,对于不同组成的含油污泥,由其测定的油含量与含油污泥样品实际油含量的相对偏差均小于5%,由其测定的水含量与含油污泥样品实际水含量的相对偏差均小于7%。在测定效率方面,高效抽提法也优于其他2种方法,40min即可完成10g油一水一固质量比为3:2:5含油污泥中油、水含量的测定。 相似文献
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Supercritical fluid extraction (SFE) is a rapid and convenient method for the isolation of organic compounds from environmental samples. This paper describes a supercritical carbon dioxide (CO2) extraction system that uses a newly designed extraction cell to recover organic compounds from an aqueous matrix. Analysis of the extracts by gas chromatography-electron capture detector (GC-ECD) indicated that the herbicide trifluralin (2,6-dinitro-N,N-dipropyl-4-trifluoromethylaniline) could be quantitatively extracted by using the SFE system proposed with small amounts of sample. The percentage of recovery obtained with the SFE system described was twice as high as the result obtained using a conventional solid-phase extraction technique. Extraction by SFE was completed in a short period of time using a simple and low-cost home-made system that did not require the use of organic solvents. 相似文献
16.
Bruno Spinosa DeMartinis Fernando Mauro Lanças 《Journal of environmental science and health. Part. B》2013,48(5):539-547
Abstract Supercritical fluid extraction (SFE) is a rapid and convenient method for the isolation of organic compounds from environmental samples. This paper describes a supercritical carbon dioxide (CO2) extraction system that uses a newly designed extraction cell to recover organic compounds from an aqueous matrix. Analysis of the extracts by gas chromatography‐electron capture detector (GC‐ECD) indicated that the herbicide trifluralin (2,6‐dinitro‐N,N‐dipropyl‐4‐trifluoromethylaniline) could be quantitatively extracted by using the SFE system proposed with small amounts of sample. The percentage of recovery obtained with the SFE system described was twice as high as the result obtained using a conventional solid‐phase extraction technique. Extraction by SFE was completed in a short period of time using a simple and low‐cost home‐made system that did not require the use of organic solvents. 相似文献
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Selective supercritical fluid extraction (SFE) at 40 degrees C, 400 bar and 60 min was used to selectively remove bioavailable PCBs from a naturally contaminated limnic sediment. The extraction decreased the sediment concentrations of the nine studied PCBs by 54% (on average). Chironomid larvae were thereafter cultured in pre-extracted sediment as well as in untreated sediment to study the differences in uptake of PCBs in the two cultures. While the prevailing equilibrium partitioning (EqP) theory predicts a 54% decrease in PCB uptake by the chironomids in the pre-extracted sediment, with a maintained biota-to-sediment accumulation factor (BSAF), a decrease in PCB uptake by 91% was observed. For all investigated PCBs the BSAFs were on average 81% lower in the cultures with pre-extracted sediment than in the untreated systems. The data allowed for a calculation of the bioavailable fraction, which was estimated to 60%. This is very close to the 54% removed by selective SFE, demonstrating the possibility of using SFE as a tool to determine the bioavailable PCB fraction in a polluted sediment. 相似文献
18.
Stroud JL Rhodes AH Semple KT Simek Z Hofman J 《Environmental pollution (Barking, Essex : 1987)》2008,156(3):664-670
The aim of this paper was to measure the changing desorbable fraction and bioaccessibility of phenanthrene in two different soils with increasing soil-phenanthrene contact time using supercritical fluid extractions (SFE). Both soils were spiked with 100 mg kg−1 phenanthrene and aged for 28 d. Desorption profiles were measured every 7 d using selective SFE conditions and the results were compared to 14C-phenanthrene mineralisation assays. Selective SFE showed significant differences in the rates and extents of desorption in the two soils, likely to be due to different organic matter composition. Post-extraction fitting of data yielded consistent SFE extraction times within ageing soils for bioaccessibility prediction. 相似文献
19.
Xiaobin Hu Jinyun Ye Rongfei Zhang Xiang Wu Yixiang Zhang Chenglong Wu 《Journal of environmental science and health. Part. B》2017,52(10):770-776
MC analysis of biological tissue is considered to be very difficult due to the lack of validated methods. This is the primary limiting factor for monitoring potential risks in both the flesh of aquatic organisms and the aquatic ecosystem. In this study, an effective method to determine free MCs (MC-LR and MC-RR) in the muscle and liver tissues of freshwater cultured fish was developed using solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC/MS-MS). The extraction solvent, time of extraction, eluent and purification of the extract were optimized. Various SPE cartridges were also investigated. In this optimized analytical procedure, an 85% methanol/water solution (v/v) was selected as the extraction solvent, after which the extracts were purified by removing fats and proteins; a HLB cartridge was chosen for MCs enrichment; and 90% methanol containing 0.02% formic acid/water solution (v/v) was used as the eluent. Under the optimized pretreatment conditions and instrument parameters, good recoveries of MC-LR and MC-RR were obtained at three concentrations (0.5, 1.0 and 2.0 µg g?1 dry weight (DW)), with values ranging from 92.5 to 98.3% and 92.1 to 98.6%, respectively. The method detection limit (MDL) for muscle samples was 0.5 µg kg?1 and 0.4 µg kg?1 (DW) for MC-LR and MC-RR, respectively. The MDL for the liver samples was 0.8 µg kg?1 (DW) for both MC-LR and MC-RR. The developed procedure was successfully applied to analyze MCs in the muscle and liver of fish samples collected from a Chinese freshwater aquaculture pond during bloom seasons. The MC-LR concentrations ranged from below the MDL to 4.17 µg kg?1 and the MC-RR concentrations ranged from below the MDL to 2.64 µg kg?1. 相似文献
20.
《Environmental Forensics》2013,14(4):313-317
Supercritical fluid extraction (SFE) was investigated to evaluate its potential for obtaining high quality chromatographic fingerprints from soils encountered in environmental investigations. While the volatile and semivolatile fractions of light nonaqueous phase liquid (LNAPL) samples can be “fingerprinted” in a single chromatographic run, it is commonly not possible to obtain samples of LNAPL in the locations of interest. For this and other reasons, it was desirable to develop this method (SFE) of soil extraction, which allows chromatographic fingerprinting of the same quality routinely obtained with LNAPL so that environmental forensic investigations could be extended to areas beyond those containing LNAPL in monitoring wells. In this study, SFE was compared to conventional dichloromethane extraction. Both artificially spiked soil and soil from petroleum release sites were tested. Since water can be a problem when using the SFE method, particular attention was given to handling soils with high moisture contents. The SFE extracts showed excellent retention of low molecular components, including pentanes. Gas chromatography of SFE extracts yielded molecular distributions that showed no significant bias toward either low or high molecular weight components. These results show that SFE can be used to obtain an unbiased, single-run chromatographic “fingerprint” of both volatile and semivolatile hydrocarbons in contaminated soil samples. 相似文献