Abstract：A new method has been developed for the extraction of capsaicinoids (nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin and homodihydrocapsaicin) in peppers employing microwave-assisted extraction. The parameters studied are: extraction solvent (methanol, ethanol,acetone, ethyl acetate and water), temperature (50–200 ◦C), sample quantity (0.1–1 g), volume of solvent (15–50 mL) and the extraction time(5–20 min). The results found for the optimum conditions are: 125 ◦C as extraction temperature, 25mL of solvent, 0.5 g of freshly triturated peppers and extraction for 5 min, employing 100% ethanol as solvent. The capsaicinoids obtained were stable under the optimised extraction conditions. The resulting method presents a high degree of reproducibility (R.S.D. < 6%).
Abstract：Amethod is reported for the determination of the quinolones oxolinic acid and flumequine in aquatic sediments and agricultural soils. The analytes are extracted by liquid–liquid partitioning between a sample homogenated in an aqueous buffer solution and dichloromethane. Microwave-assisted extraction (MAE) was tested to improve the speed and efficiency of the extraction process. The parameters affecting the efficiency of MAE, such as irradiation time and temperature, were studied. The clean-up consists of back-extraction in 1M sodium hydroxide. The determination is carried out by reversed phase liquid chromatography on an octyl silica-based column and fluorimetric detection.
The optimised method was applied to the analysis of two sediments and one agricultural soil spiked with the analytes. The absolute recovery rates for the whole process range from 79% to 94% (RSD 3–7%), and detection limits are in the low g kg−1 level.
Abstract Arapid dynamic microwave-assisted extraction and on-line detection by spectrophotometry is proposed for the determination of safflower yellow in Flos Carthami. A high pressure and a peristaltic pump were used to deliver the solvent. A TM010 microwave resonance cavity was applied to concentrate the microwave energy and the forward power about 60Wwas enough for the extraction. Other extraction conditions also were examined and optimized. In this work, the extraction process can be monitored by measuring the absorption of safflower yellow in the extract, which would be convenient for rapid optimization of the extraction process. The detection and quantification limits are 8 and 27 gmL−1, respectively. The within-day and between-day precision (R.S.D.) are 1.6–3.2% and 2.8–4.2%, respectively. Compared with off-line detection, the proposed method may provide more rapid measurement and is more convenient for obtaining continuous measurements. Dynamic microwave-assisted extraction coupled with on-line spectrophotometric determination of safflower yellow in Flos Carthami
Abstract This work describes the utilization of the focused microwave-assisted micellar extraction in combination with the solid-phase microextraction(SPME) to determine chlorophenols in wood samples. The influence of the nature of the surfactant in the extraction process, the optimization of the variables of the focused-microwave system, and the effect of the ageing time of the samples in the extraction efficiency of the method, have been assessed in this study. The overall method using the non-ionic surfactant POLE as extracting medium allows us to determine chlorophenols in wood samples achieving an average extraction efficiency of 104.1%, limits of detection ranging from 2 to 120 ng g−1, and intermediate precision values ranging between 3.5 and 13.2%. The proposed method is also characterized by short analysis times (around 5 min for the microwaves extraction step) and by avoiding the use of organic solvents. Focused microwave-assisted micellar extraction combined with solid-phase microextraction—GCMS to determine chlorophenols in wood samples
Abstract Microwave assisted micellar extraction (MAME) coupled with solid phase microextraction (SPME) and HPLC-UV determination have been used for the determination of five organochlorine pesticides from agricultural soil samples. A non-ionic surfactant, Polyoxyethlylene 10 Lauryl Ether was used, and the different variables for the optimization of MAME and SPME procedures were studied. This method was applied successfully to the determination of these pesticides in several kinds of agricultural soil samples with different characteristics. Most of the compounds studied can be recovered in good yields with R.S.D. lower than 9% and detection limit ranged between 56–96 ng g-1 for the pesticides studied. Microwave assisted micellar extraction coupled with solid phase microextraction for the determination of organochlorine pesticides in soil samples
Abstract Microwave-assisted extraction (MAE) has been evaluated as an alternative to dialysis for extraction of some water-borne hydrophobic contaminants sampled by semi-permeable membrane devices (SPMDs). Seven organochlorine pesticides (OCPs), 11 polychlorinated biphenyls (PCBs) and 13 polycyclic aromatic hydrocarbons (PAHs) were accumulated in SPMDs at nanogram levels and extracted with three 3-min irradiation cycles with 33mL of a solvent mixture hexane–water (10:1,v/v) in each cycle. The developed MAE method gave for all analytes investigated statistically comparable extraction yields with those found by dialysis carried out with a total volume of 250mL hexane for 48 h at room temperature. The recoveries of all the targeted contaminants were in the range of 65–105% with variation coefficients not exceeding 19%. The applicability of the MAE extraction was tested in field SPMDs samples deployed for 15 days in a sewage-treatment process. Our results show that MAE provides a remarkable reduction of time and solvent volume when used as an extraction method in the analysis of SPMDs. Microwave-assisted extraction of OCPs, PCBs and PAHs concentrated by semi-permeable membrane devices (SPMDs)
Abstract Microwave-assisted extraction (MAE) has been evaluated as an alternative to dialysis for the extraction of polybrominated diphenyl ethers(PBDEs) and polychlorinated naphthalenes (PCNs) sampled by semipermeable membrane devices (SPMDs), using gas chromatography coupled to tandem mass spectrometry (GC–MS–MS).
For MAE optimization a two level full factorial design 23, plus a centre point, which involves 11 randomized runs was used. The results showed that the temperature had a significant influence on the extraction of the nine PBDEs and four PCNs tested. Also, the solvent volume had a positive influence on the extraction of PBDEs and PCNs, but only in latter compounds, it achieves statistical significance. The time had only statistical significance for the most volatile specie studied, PCN-54. The selected MAE conditions (60mL of hexane–acetone, 1:1 (v/v), 85 ◦C, 1 min, two cycles) lead to recoveries between 72 and 91% for PBDEs and between 96 and 103% for PCNs. The applicability of the MAE extraction was tested in field SPMDs deployed for 20 days in a sewage treatment plant.
Abstract A rapid and environmentally friendly methodology was developed for the extraction of pyrethroid insecticides from semi permeable membrane devices (SPMDs), in which they were preconcentrated in gas phase. The method was based on gas chromatography mass–mass spectrometry determination after a microwave-assisted extraction, in front of the widely employed dialysis method. SPMDs were extracted twice with 30mL hexane:acetone, irradiated with 250Wpower output, until 90 ◦C in 10 min, this temperature being held for another 10 min. Clean-up of the extracts was performed by acetonitrile–hexane partitioning and solid-phase extraction (SPE) with a combined cartridge of 2 g basic-alumina, deactivated with 5% water, and 500 mg C18.
Pyrethroids investigated were Allethrin, Prallethrin, Tetramethrin, Bifenthrin, Phenothrin, -Cyhalothrin, Permethrin, Cyfluthrin, Cypermethrin,Flucythrinate, Esfenvalerate, Fluvalinate and Deltamethrin. The main pyrethroid synergist compound, Pyperonyl Butoxide, was also studied. Limit of detection values ranging from 0.3 to 0.9 ng/SPMD and repeatability data, as relative standard deviation, from 2.9 to 9.4%, were achieved.Pyrethroid recoveries, for spiked SPMDs, with 100 ng of each one of the pyrethroids evaluated, were from 61±8 to 103±7% for microwaveassisted extraction, versus 54±4 to 104±3% for dialysis reference method. Substantial reduction of solvent consumed (from 400 to 60 mL) and analysis time (from 48 to 1 h) was achieved by using the developed procedure.
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