Determination of betamethasone-17-valerate in betason and urine samples using polyurethane foam modified with bromophenol blueAuthor(s): Samah A.M.Ali, Sami M.Abdel Azeem, Mohamed F.El-Shahat
A simple and sensitive spectrophotometric determination of betamethasone valerate (BV) in pharmaceutical and urine samples using on-line preconcentration system. A minicolumn packed with bromophenol blue grafted polyurethane foam (BPB-PUF) has been used for the preconcentration of BV. The optimum preconcentration conditions were based on the extraction of the BV at pH 9.5, preconcentration time 90s and flow rate 1.0 mL min-1. Desorption of BV was effected by passing 300 ìL, 0.50 mol L-1 hydrochloric acid as eluent. The preconcentration system provides a linearity range 0.05 30 ìg mL-1. The limits of detection and quantification are 0.02 mg L-1 and 0.07 mg L-1, respectively. The developed approach provided an enrichment factor 74 fold within the concentration range 2.0 - 15.0 mg L-1. Method precision expressed as relative standard deviation (RSD) was found to be 1.9 % for six replicate measurements at concentration level 5.0 mg L-1. The method was successfully applied to the determination of BV in pharmaceutical and spiked urine samples with recovery ranged from 101 to 104% and RSDs less than 4.5%.