RESUMO
Simple, selective and highly sensitive spectrophotometric methods are proposed for the rapid and accurate determination of anti-hypertensive drugs namely telmisartan (TEL), propranolol (PRO), bisoprolol (BIS) and carvedilol (CRV) in tablets and biological fluids using bromocressol green (BCG) and bromothymol blue (BTB). The developed methods involve formation of stable yellow colored dichloromethane extractable ion-pair complexes of the amino derivative of four antihypertensive drugs such as TEL, PRO, BIS and CRV with two sulphonphthalein acid dyes, namely; BCG and BTB in acidic buffer. The effect of optimum conditions via pH on the ion-pair formation, reagent concentration, time and temperature and solvent was studied. The composition of the ion-pairs was found 1: 1 by Job’s method. The established methods having high sensitivity and good selectivity could be applied to the determination of the studied drugs in pharmaceutical, urine and blood serum samples with satisfactory results. The results obtained are good agreement with experimental data. The reaction mechanism was also discussed.
RESUMO
Simple, accurate, precise, and rapid extractive spectrophotometric method was developed for the determination of four antipsychotics drugs, namely sulpiride (SUP), olanzapine (OLP), clozapine (CLP) and aripiprazole (ARP) both in tablets and in biological fluids. The method was based on the formation of red colored ion-pair complex between the studied drugs and eriochrome black T (EBT) with absorption maxima at 514 nm. The stoichiometry of the complexes in either case was found to be 1: 1 and the conditional stability constant (Kf) of the complexes have been calculated. Reaction conditions were optimized to obtain the maximum color intensity. Beer’s law was obeyed in the concentration ranges of 4-30, 4-20, 2-18 and 4-26 μg/ml with SUP, OLP, CLP and ARP, respectively. Various analytical parameters have been evaluated and the results have been validated by satistical data. The proposed method was successfully applied to the analysis of commercial tablets containing the drugs and the results were in good agreement with those obtained with reported methods. The proposed method was further applied to the determination of the studied drugs in spiked human serum and urine. A proposal for the reaction pathway was postulated.