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New concept for HPTLC peak purity assessment and identification of drugs in multi-component mixtures.

Talanta (2012-01-24)
Ismail I Hewala, Mona M Bedair, Sherif M Shousha
ABSTRACT

Simple methods for HPTLC peak purity assessment and identification of the HPTLC peaks were presented. The spectrodensitograms - selected at different time intervals across the elution time of the HPTLC peak - were extracted and digital algorithms for manipulating the data were carried out in the wavelength domain. Three different methods were developed for testing the HPTLC peak purity using the mathematically transformed data of the spectrodensitograms. These included the method of relative absorption, the method of logA versus the wavelength plots and the derivative (first, second, third and fourth) method. The identification of the HPTLC peaks was based on the use of the derivative profile of the spectrodensitogram and the derivative ratios as fingerprints for the compounds. The wavelengths of absorbance and derivative (first, second, third and fourth) optima of the extracted spectrodensitograms were allocated. The data were compared with those obtained using the corresponding reference standard. The validity of the proposed methods was performed by chromatography of a mixture containing mebendazole and methylparaben as a model versus the winCATS(®) spectral correlation method as a reference method. The study indicated that the proposed concept is a reliable non-confusing valuable tool for testing the purity and identity of the HPTLC peaks as the results are easily and rigorously interpreted.

MATERIALS
Product Number
Brand
Product Description

Supelco
Methylparaben, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Methyl 4-hydroxybenzoate, ReagentPlus®, ≥99.0%, crystalline
Supelco
Methyl Paraben, PESTANAL®, analytical standard
Methyl parahydroxybenzoate, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
Methyl 4-hydroxybenzoate, ≥99%, FCC
Sigma-Aldrich
Methyl 4-hydroxybenzoate, BioReagent, suitable for insect cell culture
Sigma-Aldrich
Methyl 4-hydroxybenzoate, BioXtra, ≥99.0% (titration)
Sigma-Aldrich
Methyl 4-hydroxybenzoate, tested according to Ph. Eur.
Sigma-Aldrich
Methyl 4-hydroxybenzoate, analytical standard