Authors:Bugusu Nyamweru, Eliangiringa Kaale, Veronica Mugoyela and Mhina Chambuso
Analysis of fixed dose combination products can present daunting challenges to the analytical chemist. This paper presents a validated analytical method for simultaneous analysis of lamivudine, tenofovir disoproxil fumarate, and efavirenz using high-performance thin-layer liquid chromatography (HPTLC)-densitometric method. Separation was achieved by use of HPTLC pre coated plate with silica gel 60F254 using mobile phase containing toluene-methanol (27:6 v/v). RF values were 0.18 ± 0.02 for lamivudine, 0.33 ± 0.05 for tenofovir disoproxil fumarate, and 0.48 ± 0.02 for efavirenz, respectively. The regression line had best fit using second order polynomial function for all the three APIs (active pharmaceutical ingredients) with r2 ≥ 0.98 at the concentrations of 375–900 ng spot−1 for lamivudine, tenofovir disoproxil fumarate and 750–1800 ng spot−1 for efavirenz, respectively. Repeatability and intermediate precision had % RSD ≤ 2. The method had acceptable level of accuracy for all three APIs with mean recoveries in the range of 98 to 103% with a good selectivity for the APIs. The validated method was tested for cleaning validation with limit of detection and quantitation being 1.03 ng μL−1 and 3.22 ng μL−1, respectively. The method is thus suitable for use as an analytical method to support efavirenz cleaning validation, routine drug screening, and analysis in resource constrained countries.
Authors:Bugusu Nyamweru, Joseph Sempombe, Eliangiringa Kaale and Thomas Layloff
A thin-layer chromatography (TLC) method for the analysis of clotrimazole was developed and validated according to the International Conference on Harmonization (ICH) and the United States Pharmacopeia (USP) guidelines. The developed method will be used for a qualitative and quantitative analysis of clotrimazole in vaginal tablets. The method was developed using mobile phase containing toluene-acetone (15:10 v/v) on precoated TLC silica gel 60 F254 glass plates at a detection wavelength of 215 nm using reflectance absorbance and saturation time of 20 min. Densitometric analysis showed clotrimazole being retained at RF of 0.27. The method had acceptable level of specificity where no interference was observed between clotrimazole peaks to that of blank. The calibration curve of clotrimazole was estimated using both linear and polynomial regression function in the range of 1000–2400 ng spot−1 with regression coefficient, r2, of 0.992 for linear and 0.999 for polynomial regression. The accuracy at nominal concentration of clotrimazole was found to be 99.14%, and % RSD was 1.13% for repeatability and 1.30% for intermediate precision that involved two analysts. The developed analytical method is useful for the determination of clotrimazole in the finished drug formulation. Also it helps to identify substandard and fake medicines labeled as clotrimazole during postmarketing surveillance of the drug and especially in resource-constrained countries.
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.
Authors:Nelson E. Masota, Prosper Tibalinda, Raphael Shedafa, Joseph Sempombe and Eliangiringa A. Kaale
A new high-performance thin-layer chromatographic (HPTLC)—densitometric method which can be employed in the routine analysis of miconazole in creams has been developed and validated as per the International Conference on Harmonization (ICH) guidelines and the United States Pharmacopeia (USP) guidance. The method involves the use of a mobile phase composed of safer reagents for both the user and the environment than the previously available methods. In this method, ethyl acetate—ammonia solution 25% (25:0.5 v/v) was an optimum composition of a solvent system on precoated HPTLC silica gel 60 F254 glass plates with a saturation time of 25 min and migration rate of 10.5 min per 70 mm migration distance. The Rf value was 0.57 with no interferences from excipients or solvents at the detection wavelength of 228 nm. The relative standard deviation (RSD) values of 1.14 and 1.98 were obtained for repeatability and intermediate precision, respectively, of the method. The polynomial R2 values computed on three successive days for linearity testing were 0.984, 9.81, and 0.992. Accuracy values between 97.95% and 106.86% were obtained when testing was performed at 80%, 100%, and 120% concentration levels. The method is of acceptable selectivity and reproducibility as well as of easy use.
Authors:Danstan Shewiyo, Eliangiringa Kaale, Peter Risha, Hiiti Sillo, Bieke Dejaegher, J. Smeyers-Verbeke and Yvan Heyden
This paper presents the development and validation of an improved method for the analysis of fluconazole using high-performance thinlayer chromatography (HPTLC) with densitometric detection. Separation was performed on silica gel 60 F254 plates. The mobile phase is comprised of ethyl acetate-methanol-ammonia-diaminoethane (85:10:5:0.5 ν/ν/ν/ν). Detection wavelength was 216 nm and the RF value obtained was 0.4 ± 0.03. An F-test indicated that the calibration graph was linear at the evaluated concentration range. The %RSD for repeatability and intermediate precision were 1.60 and 3.05, respectively. The mean percentage recovery for the trueness was 99.1 ± 2.1%. This method was successfully used to analyze the fluconazole content in marketed tablet samples.
Authors:Yonah H. Mwalwisi, Ludwig Hoellein, Danstan H. Shewiyo, Ulrike Holzgrabe and Eliangiringa Kaale
For quality evaluation purposes, a simple, cost-effective, precise, accurate, and rapid planar chromatographic method was developed and validated for the separation of sulfadoxine, sulfalene, and pyrimethamine using standard thin-layer chromatographic plates and a mobile phase consisting of a mixture of toluene, ethyl acetate, and methanol in the ratio 50:28.5:21.5 (% v/v). Densitometric evaluation was carried out by scanning the plates at a wavelength of λ = 254 nm. The method was validated with respect to specificity, linearity, precision, and accuracy. Linearity was proven in a concentration range of 1.00–3.00 μg per spot for sulfalene/sulfadoxine and 0.050–0.150 μg per spot for pyrimethamine with linear regression coefficients (R2) of 0.980–0.990 for all substances. The values for limit of detection (LOD) were 0.107 ng per spot for sulfadoxine, 0.044 ng per spot for sulfalene, and 1.623 ng per spot for pyrimethamine, whereas those for limit of quantification (LOQ) were found to be 0.324 ng per spot for sulfadoxine, 0.133 ng per spot for sulfalene, and 4.92 ng per spot for pyrimethamine.