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Abstract Background The aim of the present study was to develop and validate an inductively coupled plasma optical emission spectroscopic (ICP–OES) method for quantification of elemental impurities, i.e., Lead, Palladium, and Zinc, in voriconazole drug substance, and this method was employed for the regular sample analysis of Lead, Palladium, and Zinc in voriconazole drug substance for pharmaceutical use. The method has been validated using RF power of 1150 W, auxiliary gas of 0.5 L/min, and nebulizer flow of 0.4 L/min and plasma view at axial mode for Lead and Palladium and radial mode for Zinc. The wavelength was monitored for Lead, Palladium, and Zinc at 220.3 nm, 340.4 nm, and 213.8 nm respectively. Results The method is selective and is capable of detecting desired elemental impurities with regulatory acceptance limits in the presence of other elements. The validation experiments involve the demonstration of system suitability, specificity, LOD and LOQ, linearity, precision, and accuracy experiments. The linearity results obtained ˃ 0.9990 for all three impurities. Conclusion The proposed method is simple, sensitive quality control tool for the simultaneous quantitative determination of Lead, Palladium, and Zinc at low levels in voriconazole drug substance. Graphical abstract

Simple, sensitive and selective methods are proposed for the spectrophotometric determination of drugs, viz., tetracycline HCl, nifurtimox, ethionamide, propranolol HCl 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 HCl and the unreacted NBS is determined by the measurement of the decrease in the absorbance of the dye celestine blue (λ 540 nm), 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 μg/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%. [ABSTRACT FROM AUTHOR]