Abstract. Simple, sensitive and selective methods are proposed for the spectrophotometric determination of drugs, viz., tetracycline HC1, nifurtimox, ethionamide, propranolol HC1 and isonicotinic acid hydrazide, based on their reactivity with N-bromosuccinimide (NBS). The method involves the addition of excess NBS of known concentration in the presence of 0.25 M HC1 and the unreacted NBS is determined by the measurement of the decrease in the absorbance of the dye celestine blue (2m,x 540 rim), which was found to be the most suitable of several dyes tested. This method was applied for the determination of drug contents in pharamaceutical formulations and enabled the determination of the drugs in microgram quantities (0.2 to 5 gg/ml). Standard deviations were typically ~<0.5mg per dose (RSD 0.1-1.0%). No interferences were observed from excipients and the validity of the method was tested against reference method. Recoveries were 99.8-101.1%.
A simple and sensitive method is proposed for the spectrophotometric determination of drugs, viz. isoniazid, trimeprazine tartarate, pyridoxine HCI and captopril based on their reactivity with potassium bromate. The method involves the addition of excess KBt03 of known concentration in the presence of 0.7M HCl and the unreacted KBr03 is determined by the measurement of the decrease in the
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