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A sensitive spectrophotometric method is described for the determination of atenolol (ATE), timolol maleate (TIM), captopril (CPL) and diltiazem hydrochloride (DIL.HCl) in bulk drugs and in pharmaceutical preparations. The method is based on the oxidation of the studied drugs by a known excess of cerric (IV) in acid medium followed by determination of unreacted oxidant by adding a fixed amount of methyl orange dye (MO) and the increasing in absorbance is measured at 510 nm. In this method the amount of cerium (IV) reacted corresponds to drugs concentration. The experimental conditions were optimized. Regression analysis of a Beer's plot showed good correlation in the concentration ranges of 3.2-6.4, 8.0-18, 3.4-5.2 and 3.6-5.2 µg/ml for ATE, TIM, CPL and DIL.HCl, respectively. The calculated molar absorptivity values are 5.28×10 4 , 3.27×10 4 , 6.43×10 4 and 1.12×10 5 L /mol cm, respectively and the corresponding Sandell's sensitivity values are 5.043, 13.2, 3.381 and 4.024 ng/cm 2 , respectively. The limit of detection (LOD) and quantification (LOQ) are reported. No interference was observed from the additives and the applicability of the method was tested by analyzing the pharmaceutical preparations containing the investigated drugs. Statistical comparison of the results with those of official methods shows excellent agreement and indicates no significant difference in precision.

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An accurate and simple preconcentration procedure was presented for cloud point extraction of Co 2+ , Ni 2+ and Cu 2+ from water, blood and urine samples. The procedure based on complexation of the metal ions with (E)-2-(2,4-dihydroxybenzylidene)-Nphenylhydrazine-1-carbothioamide (DHBPHC) and subsequent extraction into a surfactant-rich phase of Triton X-114. The optimized procedure (50 mL solution; pH 6; 1 × 10 -4 mol L -1 of DHBPHC; 0.08% (v/v) Triton X-114) exhibits linear range up to 500 µg L -1 and limit of detection of 0.34, 0.94 and 0.83 µg L -1 for Co 2+ , Ni 2+ and Cu 2+ , respectively. Most potentially interferants did not impact the extraction process. The procedure was applied for preconcentration and determination of Co 2+ , Ni 2+ and Cu 2+ in water, blood and urine by flame atomic absorption spectrometry.

Abstract. Three visible spectrophotometric methods (A-C) were developed for the analysis of some β-blocker drugs, namely atenolol (ATE) and timolol (TIM) based on their reactivity with bromine, generated in situ by the action of hydrochloric acid on bromate-bromide mixture. The determination of residual bromine is based on its ability to bleach the indigo carmine dye and measuring the absorbance at 610 nm (method A). Methods B and C involve treating the unreacted bromine with a measured excess of iron (II), the remaining iron (II) is complexed with 1,10-phenanthroline (method B) or with 2,2 -bipyridyl (method C) and measuring the increase in absorbance at 510 and 522 nm, respectively. In all the methods, the amount of bromine reacted corresponding to the drug content. Regression analysis of Beer's plot showed good correlation in the concentration ranges of 0.4-16.4, 0.8-10.4 and 0.4-12.8 µg/ml using methods A-C, respectively, for ATE and 14-38, 12-32 and 14-38 µg/ml using methods A-C, respectively, for TIM. The optimum reaction conditions and other analytical parameters are evaluated. No interference was observed from the additives and the applicability of the methods was tested by analyzing the pharmaceutical preparations containing the investigated drugs. Statistical comparison of the results with those of official methods shows excellent agreement and indicates no significant difference in precision.