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Highlights: [•] Different extraction methods affected the antioxidant activity differently. [•] Power was the key parameter in ultrasonic and microwave extraction. [•] Powers of 300W and 600W were two critical points in microwave extraction. [•] Sevag reagent combined with H2O2 was best for protein and pigment removal. [ABSTRACT FROM AUTHOR]

Abstract: The contents of 12 ginsenosides (Rg1, Re, F11, Rf, Rg2, Rh1, Rb1, Rc, Rb2, Rb3, Rd, Rh2) in different parts and ages of Panax quinquefolius L. (American ginseng) were quantified by high pressure microwave-assisted extraction (HPMAE) high-performance liquid chromatography coupled with evaporative light scattering detection (HPLC-ELSD). The analytical method was established and analytical performances were evaluated. The chemical marker of American ginseng F11 was detected, and Rf which is the chemical marker of Asian ginseng was not found. Rare ginsenoside Rh1, Rg2 and Rh2 were also studied in this experiment. The total contents of these 12 ginsenosides in the different parts of 5-year-old American ginseng follow this order: leaf>root-hair>rhizome>root>stem. Therefore, compared with the other parts of American ginseng, the leaf is a better available source of ginsenosides. The contents of ginsenosides in root and leaf also change with age. [Copyright &y& Elsevier]

Abstract: Ultrasonic nebulization extraction (UNE) coupled with on-line gas chromatography (GC) was proposed for the determination of trans-anethole in fruits of Illicium verum Hook. f. and Foeniculum vulgare Mill. The extraction was performed in a common self-made extraction system. In the UNE the analyte was transferred and enriched from the solid sample to gas phase. The sample gas containing analyte obtained by UNE was introduced into the sampling loop with the purging gas (N2). And then the sample gas in the sampling loop was introduced into the GC column. Several experimental parameters of on-line UNE-GC, including sampling time, flow rate of purging gas, standstill time and temperature of tubing, were optimized. The calibration curve ranging from 0.05 to 1.5mgg−1 for determining the trans-anethole was obtained. The recoveries for determining trans-anethole are between 99.2% and 111.2% and RSDs are less than 8.3% when the UNE was applied. The analytes can rapidly be extracted and transferred from the solid sample to gas phase. The analytes in the gas phase are easier to be introduced into GC system than those in the solid and liquid phase. Compared with off-line systems, the proposed on-line system is more suitable to detect volatile compounds. [Copyright &y& Elsevier]

Abstract: An apparatus for extraction of flavonoids from Herba Epimedii has been constructed which utilizes a microwave technique for heating in a dynamic mode. A TM010 microwave resonance cavity was applied to concentrate the microwave energy; the power needed to achieve efficient extraction was significantly reduced. The method has been compared with other extraction methods, such as pressurized microwave-assisted extraction (PMAE), ultrasonic extraction (UE), heat reflux extraction (RE) and Soxhlet extraction (SOX). The four flavonoids in extract were identified by HPLC–MS. The influence of extraction parameters on the extraction yield of flavonoids has been evaluated by comparison with the peak areas of HPLC-DAD spectra in the different extraction methods. The results showed that the extraction yield of flavonoids in Herba Epimedii obtained by dynamic microwave-assisted extraction (DMAE) was higher than that obtained by UE, RE and SOX, and the extraction time is dramatically reduced. The extraction yield obtained by DMAE is similar to that obtained by PMAE. But the flavonoids in Herba Epimedii would not decompose easily when increasing the extraction time in DMAE. This is the benefit of dynamic extraction system which can transfer the analytes extracted from the sample matrix with flowed fresh solvent to the out of extraction vessel. [Copyright &y& Elsevier]

Abstract: A novel technique based on dynamic microwave-assisted extraction (DMAE) coupled on-line with high-performance liquid chromatography (HPLC) through a flow injection interface has been developed for determination of andrographolide and dehydroandrographolide in Andrographis paniculata Nees. A TM010 microwave resonance cavity built in the laboratory was applied to concentrating the microwave energy. An extraction vessel was placed in microwave irradiation zone. The extraction was performed in a recirculating system. When a number of extraction cycles were completed, the fractional extract (20μL) was driven to the analytical column by 65% aqueous methanol and was measured by diode array detector (DAD) at 225nm. The optimized extraction conditions are follows: extraction solvent 60% aqueous methanol; microwave forward power 80W; extraction time 6min; extraction solvent flow-rate 1.0mLmin−1. The detection and quantification limits obtained are 0.5 and 1.7μgmL−1 for andrographolide and 0.6 and 1.9μgmL−1 for dehydroandrographolide, respectively. The within-day and between-day precision (RSD) are 2.1% and 3.7% for andrographolide and 1.7% and 4.1% for dehydroandrographolide, respectively. Mean recoveries for andrographolide and dehydroandrographolide are 97.7% and 98.7%, respectively. Compared with ultrasonic extraction used in the Chinese pharmacopoeia, the proposed method was demonstrated to obtain higher extraction yield in a shorter time. In addition, only small quantities of solvent (5mL) and sample (10mg) were required. [Copyright &y& Elsevier]