Use of polyoxyethylene surfactants for the extraction of organochlorine pesticides from agricultural soils

Analysis of glycyrrhizic acid and liquiritin in liquorice root with microwave-assisted micellar extraction and pre-concentration

The feasibility of employing a non-ionic surfactant (Triton X-100) as an alternative and effective solvent for the microwave-assisted extraction of glycyrrhizic acid and liquiritin from liquorice root has been demonstrated. When compared with commonly used solvents, 5% Triton X-100 yielded higher extraction efficiency than aqueous solutions of ethanol or methanol. Under optimal conditions, i.e. 5% Triton X-100 (v/v) and microwave-assisted extraction for 3-5 min at 100 degrees C, the percentage extraction of active ingredients reached the highest value. The pre-concentration factor for the glycyrrhizic acid and liquiritin was about 13, and the cloud-point extraction recoveries for the two ingredients were 98.4 and 96.1%, respectively. The results showed that the coupling of microwave-assisted extraction and cloud-point extraction could be employed as a new and effective approach for the rapid extraction and pre-concentration of pharmacologically active ingredients from liquorice root without disturbing the subsequent chromatographic analysis.

Application of non-ionic surfactant in the microwave-assisted extraction of alkaloids from Rhizoma Coptidis

The feasibility of employing non-ionic surfactant oligoethylene glycol monoalkyl ether (Genapol X-080) as an alternative and effective solvent for the microwave-assisted extraction of alkaloids from Rhizoma Coptidis was demonstrated. When compared with commonly used solvents, 5% Genapol X-080 enhanced the extraction efficiency. Under optimal conditions, i.e. 5% acidified Genapol X-080 (v/v), microwave-assisted extraction for 10 min at 100 degrees C, the extraction recovery of alkaloids reached 92.8% in a one-step extraction. The efficiency of cloud-point preconcentration of three alkaloids was in the range 93.6-94.7% with relative standard deviation lower than 3.3% by the proposed procedure. Furthermore, the combination of microwave-assisted extraction and cloud-point extraction was shown to be a green, rapid and effective approach for alkaloids preconcentration of Rhizoma Coptidis samples.

Pesticides analysis by liquid chromatography and capillary electrophoresis

Nowadays, a wide range of pesticides are used in agricultural production, and their monitoring in samples of environmental and alimentary interest is of extreme importance to ensure, among others, the safety of consumption of foods. The aim of this work is to provide updated information about the major developments in CE and HPLC in pesticide analysis, covering relevant publications between 2004 and early 2006. The use of different sample pretreatment steps to provide a suitable extraction of these compounds from the different matrices as well as to increase the sensitivity of the determination is also discussed.

Sample extraction method combining micellar extraction-SPME and HPLC for the determination of organochlorine pesticides in agricultural soils

A method for the determination of organochlorine pesticides in soil samples combining microwave assisted micellar extraction (MAME) with solid-phase microextraction (SPME) and high-performance liquid chromatography-UV has been developed. A mixture of two nonionic surfactants (polyoxyethylene 10 lauryl ether and polyoxyethylene 10 stearyl ether) was used for the extraction of pesticides from agricultural soils, and different types of SPME fibers were compared. The different parameters which affect extraction efficiency in the SPME procedure were optimized such as extraction time and temperature. The method developed involves extraction and preconcentration for the target analytes in soil samples. The analytical parameters were also studied and good recoveries obtained, RSD being lower than 10% and detection limits ranging between 36 and 164 ng g(-1) for the pesticides studied. The proposed method was successfully applied to the determination of some organochlorine pesticides in several kinds of agricultural soil samples with different characteristics.

Optimisation of solid-phase microextraction coupled to HPLC-UV for the determination of organochlorine pesticides and their metabolites in environmental liquid samples

A solid-phase microextraction (SPME) procedure using two commercial fibers coupled with high-performance liquid chromatography (HPLC) is presented for the extraction and determination of organochlorine pesticides in water samples. We have evaluated the extraction efficiency of this kind of compound using two different fibers: 60-mum polydimethylsiloxane-divinylbenzene (PDMS-DVB) and Carbowax/TPR-100 (CW/TPR). Parameters involved in the extraction and desorption procedures (e.g. extraction time, ionic strength, extraction temperature, desorption and soaking time) were studied and optimized to achieve the maximum efficiency. Results indicate that both PDMS-DVB and CW/TPR fibers are suitable for the extraction of this type of compound, and a simple calibration curve method based on simple aqueous standards can be used. All the correlation coefficients were better than 0.9950, and the RSDs ranged from 7% to 13% for 60-mum PDMS-DVB fiber and from 3% to 10% for CW/TPR fiber. Optimized procedures were applied to the determination of a mixture of six organochlorine pesticides in environmental liquid samples (sea, sewage and ground waters), employing HPLC with UV-diode array detector.