Transfer of thin layer chromatography (TLC) methods for qualitative detection of substandard pharmaceutical products published in the Global Pharma Health Fund (GPHF) Minilab and U.S. Food and Drug Administration (FDA) Compendium of Unofficial Methods for Screening of Pharmaceuticals to high performance TLC (HPTLC)–densitometry quantitative methods using a model process has been reported earlier in a series of papers. In this paper, HPTLC-densitometry methods developed and validated using the model process are described for levocetirizine 2HCl, sertraline HCl, atorvastatin calcium trihydrate, and cyclobenzaprine HCl for which qualitative methods have not appeared in the Minilab manual or FDA Compendium, and for sulfamethoxazole + trimethoprim for which a method is published in the Minilab manual. These new methods comprise the following aspects of the model process: use of only relatively inexpensive and nontoxic solvents for sample and standard solution and mobile phase preparation, Merck KGaA Premium Purity HPTLC silica gel 60 F254 plates, semiautomated standard and sample solution application with a CAMAG Linomat 4, automated densitometry using a CAMAG Scanner 3 for detection, assessment of peak purity and identity, quantitative assay, and validation by standard addition. Qualitative TLC screening methods based on the quantitative HPTLC-densitometry methods for these pharmaceutical products were subsequently developed as supplements to the FDA Compendium and posted online with open access.
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