Pneumatic nebulization gas-solid extraction of some pesticides in liquor.

In general, solid phase extraction (SPE) was applied to the separation and concentration of analytes from liquid samples. However, the SPE generally cannot be applied directly to the separation and concentration of analytes from liquor in which the concentration of ethanol is high, because the ethanol can elute the analytes from the SPE column and the analytes can hardly been adsorbed onto the column. In the work, the pneumatic nebulization coupled with gas-solid extraction (PN-GSE) was applied to the extraction of several pesticides, including fenuron, chlortoluron, karmex, linuron and prebane, from liquor samples. The high concentration of ethanol in the liquor samples cannot elute the analytes from the SPE column. The high performance liquid chromatography was applied to the separation and determination of the analytes. Experimental parameters affecting the performances of PN-GSE, such as types and amount of packed material of the column, temperature of the spray chamber, flow rate of carrier gas, pumping rate of gas and volume of elution solvent were examined and optimized. The limits of detection for the analytes were in the range of 0.19-0.26 µg L⁻¹. Liquor samples were analyzed and the recoveries of the analytes in spiked samples were from 91.0 to 106.3%. The relative standard deviations were lower than 6.5%.

Ultrasonic nebulization extraction-heating gas flow transfer-headspace single drop microextraction of essential oil from pericarp of Zanthoxylum bungeanum Maxim.

The ultrasonic nebulization extraction-heating gas flow transfer coupled with headspace single drop microextraction (UNE-HGFT-HS-SDME) was developed for the extraction of essential oil from Zanthoxylum bungeanum Maxim. The gas chromatography-mass spectrometry was applied to the determination of the constituents in the essential oil. The contents of the constituents from essential oil obtained by the proposed method were found to be more similar to those obtained by hydro-distillation (HD) than those obtained by ultrasonic nebulization extraction coupled with headspace single drop microextraction (UNE-HS-SDME). The heating gas flow was firstly used in the analysis of the essential oil to transfer the analytes from the headspace to the solvent microdrop. The relative standard deviations for determining the five major constituents were in the range from 1.5 to 6.7%. The proposed method is a fast, sensitive, low cost and small sample consumption method for the determination of the volatile and semivolatile constituents in the plant materials.