Authors:Yonah H. Mwalwisi, Seraphina C. Omolo, Ludwig Hoellein, Danstan H. Shewiyo, Ulrike Holzgrabe and Eliangiringa Kaale
A simple, cost-effective, precise, accurate, and rapid planar chromatographic method was developed and validated for the separation and determination of amodiaquine and artesunate in tablet formulations. Both compounds were determined using high-performance thin-layer chromatography plates and a mobile phase composed of toluene, acetonitrile, methanol, ammonium acetate, and triethylamine in the ratio 10:5:3:1:0.5 (% v/v). Amodiaquine was evaluated densitometrically at a detection wavelength of λ = 345 nm, whereas artesunate was determined fluorimetrically at λ = 503 nm. The method was linear in the concentration ranges of 0.093–0.280 μg spot−1 for artesunate and 0.250–1.250 μg spot−1 for amodiaquine, respectively.
Transfer of two rapid thin-layer chromatography (TLC) screening methods used to detect markedly substandard and fake pharmaceutical products to quantitative high-performance TLC (HPTLC)-densitometry methods is demonstrated using a model procedure that was published earlier. These TLC methods for diazepam and amodiaquine are contained in a Compendium of methods by Kenyon and Layloff and a Minilab method manual from Global Pharma Health Fund E.V., respectively, for use in countries with limited resources. Merck HPTLC Premium Purity silica gel 60 F254 glass plates, automated standard and sample solution application with a CAMAG Linomat 4, and automated densitometry with a CAMAG Scanner 3 were used for detection, identification, and quantification. Sample peak identity and purity validation were carried out by spectral comparison checks available in the winCATS software. Accuracy was estimated by the standard addition approach with overspotting standard and sample solutions. HPTLC gives better efficiency, selectivity, and resolution than TLC, and the new methods overcome the deficiencies in technology related to manual application and visual zone comparison that do not allow the Compendium and Minilab TLC procedures to support regulatory compliance actions. These new methods can be fully validated according to the International Conference on Harmonization guidelines or by interlaboratory studies if required by their applications.
)–densitometry methods. The model process was applied earlier to formulations containing acetylsalicylic acid, acetaminophen, ibuprofen, and chlorpheniramine maleate [ 1 ]; mebendazole, diphenhydramine HCl, amodiaquine, and artesunate [ 2 ]; amodiaquine and diazepam [ 3