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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: 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]

Abstract: A rapid 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 60W was 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 27μgmL−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. [Copyright &y& Elsevier]