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Tsai W.-H.,National Pingtung University of Science and Technology | Huang T.-C.,National Pingtung University of Science and Technology | Chen H.-H.,National Pingtung University of Science and Technology | Wu Y.-W.,I - Shou University | And 2 more authors.
Journal of Chromatography A | Year: 2010

A salting-out assisted liquid extraction coupled with back-extraction by a water/acetonitrile/dichloromethane ternary component system combined with high-performance liquid chromatography with diode-array detection (HPLC-DAD) was developed for the extraction and determination of sulfonamides in solid tissue samples. After the homogenization of the swine muscle with acetonitrile and salt-promoted partitioning, an aliquot of 1 mL of the acetonitrile extract containing a small amount of dichloromethane (250-400 μL) was alkalinized with diethylamine. The clear organic extract obtained by centrifugation was used as a donor phase and then a small amount of water (40-55 μL) could be used as an acceptor phase to back-extract the analytes in the water/acetonitrile/dichloromethane ternary component system. In the back-extraction procedure, after mixing and centrifuging, the sedimented phase would be water and could be withdrawn easily into a microsyringe and directly injected into the HPLC system. Under the optimal conditions, recoveries were determined for swine muscle fortified at 10 ng/g and quantification was achieved by matrix-matched calibration. The calibration curves of five sulfonamides showed linearity with the coefficient of estimation above 0.998. Relative recoveries for the analytes were all from 96.5 to 109.2% with relative standard deviation of 2.7-4.0%. Preconcentration factors ranged from 16.8 to 30.6 for 1 mL of the acetonitrile extract. Limits of detection ranged from 0.2 to 1.0 ng/g. © 2009 Elsevier B.V. All rights reserved. Source


Tsai W.-H.,The Health Bureau of Kaohsiung County Government | Chuang H.-Y.,Kaohsiung Medical University | Chen H.-H.,National Pingtung University of Science and Technology | Wu Y.-W.,I - Shou University | And 2 more authors.
Journal of Chromatography A | Year: 2010

A simple sugaring-out assisted liquid-liquid extraction method combined with high-performance liquid-chromatography with fluorescence detection (HPLC-FL) was developed for the extraction and determination of sulfonamides in honey. Sample preparation consisted of acid hydrolysis to release sugar-bound sulfonamides. After derivatization with fluorescamine, the derivatives were partitioned into the organic layer under the honey (sugar)/water/acetonitrile system. The clear organic extract obtained by centrifugation could be injected into the HPLC system either directly or after dilution. Linearity was obtained with the coefficient of determination (R2) higher than 0.998 from 2 to 200ng/mL. Under the optimal conditions, recoveries were determined for honey fortified at three levels (5, 20, and 100ng/g) were 80.9-99.6% with coefficients of variation of 0.3-4.4%. Limits of detection for the sulfonamides studied were found to range from 0.6 to 0.9ng/g. © 2010 Elsevier B.V. Source


Tsai W.-H.,National Pingtung University of Science and Technology | Huang T.-C.,National Pingtung University of Science and Technology | Chen H.-H.,National Pingtung University of Science and Technology | Huang J.-J.,The Health Bureau of Kaohsiung County Government | And 3 more authors.
Journal of Chromatography A | Year: 2010

A simple coprecipitation method was developed for the determination of tetracyclines (TCs) in surface water and milk by high-performance liquid chromatography with diode-array detection (HPLC-DAD). Magnesium ion was added into the surface water or the acetonitrile (MeCN) extract of milk. After alkalinization, magnesium hydroxide precipitates which had been formed can be separated from the matrix solution easily by centrifuging and then a dissolution step was performed by adding a small amount of acid. The final solution could be introduced directly into HPLC system for the determination of the analytes. Under optimal conditions, recoveries for the analysis of spiked surface water samples ranged from 83.6% to 95.1% with relative standard deviation of 2.0-5.5%. For milk samples, relative recoveries were 95.9-104.6% with relative standard deviation of 3.4-6.7%. The enrichment factors ranged from 41.5 to 48.1 for 10 mL water samples, and from 3.6 to 4.4 for 1 mL MeCN extracts of milk. Limits of detection ranged from 0.13 to 0.51 ng/mL, and from 3.0 to 8.5 ng/g for four TCs in surface water and milk samples, respectively. © 2009 Elsevier B.V. All rights reserved. Source

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