Development and validation of an optical SPR biosensor assay for tiamulin in grass and groundwater

Tiamulin (TIA) is an antimicrobial veterinary drug administered subtherapeutically to prevent swine dysentery and pneumonia. Due to its stability, crystalline structure, and water-soluble properties, TIA is a prime candidate for environmental monitoring. However, there are currently no screening methods available for TIA in environmental matrices, such as grass or ground water. In this paper, the development and validation of a screening method using optical SPR biosensor technology is presented. A solvent extraction was carried out on samples prior to analysis using the Biacore Q instrument. The limit of detection for the assay in grass and ground water was 10.8 ng/g and 2.4 ng/ml, respectively. In addition, the assay was shown to be of an acceptable standard with regard to both accuracy and reproducibility.

Development and validation of an HPLC method for the determination of spironolactone and its metabolites in paediatric plasma samples

Abstract An HPLC method has been developed and validated for the determination of spironolactone, 7a-thiomethylspirolactone and canrenone in paediatric plasma samples. The method utilises 200 µl of plasma and sample preparation involves protein precipitation followed by Solid Phase Extraction (SPE). Determination of standard curves of peak height ratio (PHR) against concentration was performed by weighted least squares linear regression using a weighting factor of 1/concentration2. The developed method was found to be linear over concentration ranges of 30–1000 ng/ml for spironolactone and 25–1000 ng/ml for 7a-thiomethylspirolactone and canrenone. The lower limit of quantification for spironolactone, 7a-thiomethylspirolactone and canrenone were calculated as 28, 20 and 25 ng/ml, respectively. The method was shown to be applicable to the determination of spironolactone, 7a-thiomethylspirolactone and canrenone in paediatric plasma samples and also plasma from healthy human volunteers.

The development and validation of liquid chromatography method for the simultaneous determination of metformin and glipizide, gliclazide, glibenclamide or glimperide in plasma

This article describes the development of SPE and HPLC methods for the simultaneous determination of metformin and glipizide, gliclazide, glibenclamide or glimperide in plasma. Several extraction and HPLC methods have been described previously for the determination of each of these analytes in plasma separately. The simultaneous determination of these analytes is important for the routine monitoring of diabetic patients who take combination medications and for studying the pharmacokinetics of the combined dosage forms. In addition this developed method can serve as a standard method for the plasma determination of these analytes therefore saving time, effort and money. The recoveries of the developed methods were found to be between 76.3% and 101.9%. The limits of quantification were between 5 and 22.5 ng/ml. The intraday and interday precision (measured by coefficient of variation, CV%) was always less than 9%. The accuracy (measured by relative error %) was always less than 12%. Stability analysis showed that all analytes are stable for at least 3 months when stored at -70degreesC. (C) 2004 Elsevier B.V. All rights reserved.

Development and validation of a lateral flow device for the detection of nicarbazin contamination in poultry feeds

Concentrations of the coccidiostat nicarbazin as low as 2 mg/kg in feed can result in violative drug residues arising in poultry liver. A lateral flow device (LFD) was developed for the detection of contaminating concentrations of nicarbazin following solvent extraction of poultry feeds. Test results, as determined by both visual and instrumental measurement, are available within minutes. For 22 feed samples, nicarbazin-free and fortified at 2 mg/kg, the % relative inhibition ranged from 0 to 45% and from 53 to 85%, respectively. Nicarbazin contamination at the critical concentration (2 mg/kg) can be determined in all cases providing the sampling is representative. A wide range of feed samples taken at a mill that incorporated nicarbazin into poultry feed were analyzed. Data generated for these samples by both the LFDs and a mass spectrometric method were compared, and a significant correlation was achieved.