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A simple and rapid TLC-densitometric method has been developed for simultaneously determination of hydrocortisone acetate and 2-phenoxyethanol in cream. After extraction of the analyte with 96% ethanol, the extracts were spotted on precoated TLC silica gel 60 RP-18 F254s aluminum-backed sheets, which were then developed with a mixture of water-methanol (8:22, v/v). Quantitative evaluation was performed by measuring the absorbance reflectance of the analyte spots at 270 nm. The method was validated for specificity, linearity, accuracy, precision, and robustness. Good linearity was achieved in the concentration ranges of 4260–13,000 ng spot−1 (hydrocortisone acetate), and 750–4250 ng spot−1 (2-phenoxyethanol). The detection limit and quantification limit were 554 and 1660 ng spot−1 (hydrocortisone acetate), and 149 and 448 ng spot−1 (2-phenoxyethanol), respectively. No constant or proportional-systematic errors for both of the analytes were observed. RSD of repeatability and intermediate precision were found to be less than 2%. β-Expectation tolerance interval values of all VS creams were included in the tolerance interval limit λ(± 10%).

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Piperine and gallic acid are of different chemical natures — piperine is an alkaloid, while gallic acid a phenolic compound. They are used as marker compounds in many plant-based formulations. A highperformance thin-layer chromatographic (HPTLC)-densitometric method has been developed and validated for the simultaneous quantification of piperine and gallic acid as such and in pharmaceutical dosage forms. Toluene-ethyl acetate (3:7) was used as mobile phase and scanning was done at 254 and 340 nm. The method was validated with respect to linearity, reproducibility, specificity, accuracy, precision, robustness, and ruggedness. Both compounds showed good linearities in the range of 250–1750 ng. LOD and LOQ for piperine were 9.98 and 33.29 ng, while for gallic acid 25 and 83.33 ng. Average % RSD values of precision for piperine and gallic acid were 0.46% and 0.72%, respectively. % Recovery was 96–103%. The method is accurate, reproducible, cost-effective, and can be used in routine analysis.

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A densitometric high-performance thin layer chromatographic (HPTLC) method has been established for analysis of withaferin-A in Withania somnifera . The analyte was extracted with methanol. Withaferin-A standard and sample was spotted by use of a sample applicator. The plates were developed with toluene-ethyl acetate-formic acid 5:5:1 as mobile phase. Quantitative evaluation was performed by measuring the absorbance of the analyte zones at 200 nm in reflectance mode. The method was shown to have the selectivity, accuracy, precision, and high sample throughout useful for routine analysis of the preparation in industrial quality control and regulatory laboratories.

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A thin layer chromatographic method with densitometric UV detection at λ = 285 nm has been developed for quantification of embelin in Lysimachia punctata . TLC analysis was performed on aluminumbacked silica gel 60 F 254 plates with n -hexane-ethyl acetate, 7 + 3 ( v / v ), as mobile phase. Under these experimental conditions the method was highly sensitive (the limit of detection was 12.5 ng) and recovery was satisfactory (from 89.45% to 92.28%). Good results obtained during validation of the method were confirmed in quantification of embelin, because high precision and accuracy were achieved.

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A simple and rapid high-performance thin-layer chromatography (HPTLC) densitometric method has been developed for the determination of mebhydrolin napadisylate in tablets. After extraction of the analyte with a mixture of methanol and NH4OH 25% (100:1.5, v/v), the extracts were spotted on precoated HPTLC silica gel F254 plates, which were developed with a mixture of methanol and ethyl acetate (1:1, v/v). Quantitative evaluation was performed by measuring the absorbance reflectance of the analyte spots at 287 nm. The method was validated for specificity, linearity, accuracy, precision, and robustness. Good linearity was achieved in the concentration range 600–1600 ng/spot. The RSD of repeatability and intermediate precision were found to be less than 2%, whereas the mean of the recovery data was 99.3–100.8%. The detection limit and quantification limit were 18.5 and 55.5 ng/spot, respectively. The drug was subjected to acidic and alkaline hydrolysis, oxidation, dry heat, and UV treatment. The peak of mebhydrolin napadisylate was not interfered by those of possible degradation products.

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A densitometric thin-layer chromatographic method has been established for the analysis of celecoxib, etoricoxib, and valdecoxib in pharmaceutical formulations. TLC was performed on silica gel 60 F 254 plates with chloroform-acetone-toluene 12:5:2 ( v/v ) as mobile phase. UV detection was performed by densitometric scanning at 254 and 290 nm. The method was validated by determination of linearity, precision, limits of detection, and determination (from 0.0017 to 0.0848 μg per band) and accuracy (from 99.16 to 100.48%).

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A densitometric thin-layer chromatographic method has been established for quantitative determination of β-sitosterol in pumpkin seed oil ( Cucurbita pepo L.). Chromatography was performed on silica gel 60 F 254 TLC plates, with toluene-ethyl acetate-glacial acetic acid 15:4:1 ( v/v ) as mobile phase. Densitometric quantitation was performed at 525 nm. The method was validated by determination of linearity (15–750 μg mL −1 ), precision (RSD = 2.36%), and limits of detection (LOD = 0.65 μg per band) and quantification (LOQ = 1.99 μg per band). Average recovery from the pharmaceutical preparation was 96.15%. The method enables simple, rapid, and precise quantitative determination of β-sitosterol in pharmaceutical preparations and can be used for routine quality control.

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A thin-layer chromatographic method with densitometric detection has been established for quantification of azithromycin in pharmaceutical preparations. Silica gel plates with fluorescence indicator F 254 were used with chloroform-ethanol-ammonia 6:14:0.2 ( v/v ) as mobile phase. Chromatograms were visualized by spraying with 1:4 ( v/v ) sulfuric acid-ethanol and heating at 120C for 5 min. Scanning and densitometric analysis was performed at 483 nm. The R F of azithromycin under these conditions was 0.53. The method was characterized by high sensitivity (LOD = 40 ng/zone and LOQ = 80 ng/zone), wide linear range (from 0.08 to 1.2 μg/zone, r = 0.9965), and high precision, accuracy (mean percentage recovery 102.73%), and specificity.

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A TLC-densitometric method has been established for identification and quantification of tiaprofenic acid, ketoprofen, naproxen, dexibuprofen, flurbiprofen, alminoprofen, and ibuprofen in selected pharmaceutical preparations. The separation was performed on TLC silica gel F 254 plates using two mobile phases. UV densitometry was performed at 225 and 270 nm. The method is of high sensitivity; limits of detection and quantitation range from 0.05 to 0.29 μg per band. For individual constituents recovery ranged from 98.71% to 102.65%.

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Thin-layer chromatography has been used to separate a mixture of sulfur polynuclear aromatic hydrocarbons (S-PAH), heterocyclic compounds with mutagenic and carcinogenic properties. S-PAH were oxidized to give the sulfone derivatives and then S-PAH standards, their oxidized forms, and PAH were applied to silica gel and RP-18 plates and developed in a horizontal chamber with different mobile phases. After chromatography the plates were observed in UV light at λ = 254 nm and scanned densitometrically at the same wavelength. R F values were determined for the compounds.

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