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RP HPLC method for the quantification of coal tar in topical foam

Ajay Vairale, Reaz Khan, Ganesh S.Jadhav, Vijendra Nalamothu, P.Sivaswaroop

Coal tar is a brown or black liquid of high viscosity, smells like naphthalene and hydrocarbons. Coal tars are complex and variable mixtures of phenols, polycyclic aromatic hydrocarbons (PAHs), and heterocyclic compounds.A unique stability- indicating HPLC method was developed for the quantitative determination of%coal tar by quantification ofmarker peaks viz PhenanthreneAnthracene and Pyrene in pharmaceutical dosage forms in the presence of degradation products and excipients. Phenomenex Hypersil BDS 150mmx 4.6mm, 3 µm column was used to achieve separation using gradient method. The mobile phase A contains deionised water and the mobile phase B contains acetonitrile. The flowrate was 0.8 mLmin-1 and the detection wavelength was 240 nm. The retention time of phenathrene, anthracene and pyrene are 21.7, 23.8 and 29.7minutes respectively. The total run time is 60 minuteswithinwhich three marker peaks and degradation productswere separated. Calibration showed that the response of phenathrene, anthracene and pyrene was a linear function of concentration over the range 0.25-0.75 µg mL-1 (r  0.999) and the method was validated over this range for precision, intermediate precision, accuracy, linearity and specificity. Themethod was developed and validated successfully and applied to the quantitative determination of coal tar marker peaks in coal tar foamproduct.