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A new, simple and rapid thin-layer chromatography (TLC) method with densitometric detection for simultaneous determination of four oxicams, namely, piroxicam, meloxicam, tenoxicam and isoxicam, has been developed. The chromatographic separation was carried out on TLC F254 plates with a mobile phase consisting of ethyl acetate-ethanol-toluene 6:3:1 (v/v/v) + 2 drops of ammonia 25%. Quantitative determination was done by densitometric scanning at wavelength λ = 360 nm. The method was validated with respect to linearity (in the range from 0.05 to 0.50 mg per band), LOD and LOQ, accuracy (about 99.90%) and precision (RSD from 0.33% to 0.80%) in accordance with the International Conference of Harmonization guidelines. The method has been successfully applied to the analysis of drugs in the pharmaceutical formulations.
Ibuprofen is one of the most common nonsteroidal anti-inflammatory and analgesic drugs. It is marked as a racemic mixture though it is known that the pharmacological activity resides in the (+)-(S)-enantiomer only. The process of conversion of (+)-(S)-ibuprofen enantiomer into (−)-(R)-enantiomer, inactive to cyclooxygenase, in methanol and cyclohexane using a chiral selector in TLC separation was investigated. Based on the values of k, t 0.1, and t 0.5, it is shown that the interconversion of (+)-(S) into (−)-(R)-enantiomer runs 10 times faster in polar methanol than in lipophilic cyclohexane.
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%).
A chromatographic-densitometric method has been established for identification and quantification of S -(+)-2-(6-methoxy-2-naphthyl)propionic acid ( S -(+)-naproxen) and naproxen methyl ester in pharmaceutical preparations. The chromatographic separation was performed on silica gel F 254 TLC plates with cyclohexane-chloroform-methanol, 12 + 6 + 1 ( v/v ), as mobile phase. UV densitometric detection was performed at λ = 223 nm. The method is highly sensitive; the limit of detection for naproxen is 30 ng. Recovery was satisfactory at 95.4%, response was linearly dependent on quantity over a wide range, from 0.0015% to 0.0060%, and repeatability was also satisfactory. The effect of pH, temperature, and incubation time on the degradation of naproxen was investigated.
A rapid, accurate, and sensitive densitometric TLC method has been established and validated for simultaneous analysis of eight β-lactam antibiotics (cephalexin, cefadroxil, and cefazolin (first-generation), cefaclor, cefuroxime, and cefuroxime axetil (second-generation), and ceftriaxone and cefotaxime (third-generation)). Chromatographic separation was achieved on silica gel F254 plates with chloroform-ethyl acetate-glacial acetic acid-water 4:4:4:1 (v/v) as mobile phase. Densitometric detection was performed at 275 nm. Statistical evaluation showed the performance of the method was satisfactory. Accuracy was in the range 98.30–100.85% and precision, as RSD, was from 0.4 to 2.45%.
A direct, rapid, and sensitive thin-layer chromatography (TLC) method with densitometric detection was developed and validated for the determination of tenoxicam and its degradation products. The chromatographic separation was executed on silica gel TLC 60 F254 plates. Elution was performed with ethyl acetate-toluene-butylamine (2:2:1, ν/ν/ν) as mobile phase. Quantitative analysis was carried out on the basis of the peak areas obtained from reflectance scanning densitometry performed at 288 nm. The method was validated in terms of linearity (35–1820 mg mL−1), accuracy (RSD < 1%), precision (RSD < 2%), sensitivity (LOD = 0.86 mg per band; LOQ = 2.30 mg per band), selectivity, and repeatability. Degradation products were identified by the R F values, absorption spectra, and LC-MS analysis. As the method could effectively separate the drug from its degradation products (i.e., pyridine-2-amine, tiophen), it can be employed as a method to indicate the stability of the compound. Moreover, the proposed TLC method was used to investigate the kinetics of the degradation process.
A simple, selective, and sensitive thin-layer chromatography (TLC) method is described for the identification and determination of nabumetone in pharmaceutical products. The mobile phase was constituted by the following mixture: n-hexane-chloroform-glacial acetic acid 4:1:1 (ν/ν/ν); and the stationary phase was TLC plate of silica gel 60 F254. The chromatograms were developed and analyzed densitometrically at λ 1 = 270 nm and λ 2 = 330 nm. R F values and UV spectra were used to identify the compounds. The developed method was characterized by high sensitivity (LOD and LOQ (limits of detection and quantitation) from 0.23 μg per band to 1.00 mg per band), high accuracy (recovery about 100%), and good precision ((relative standard deviation, RSD < 2%).
A new, simple and rapid thin-layer chromatographic method with densitometric detection has been developed and validated for analysis of oxaprozin and its degradation products. Chromatography was performed on silica gel plates with n -hexane-chloroform-glacial acetic acid 4:1:1 ( v/v ) as mobile phase. Densitometric analysis of oxaprozin was performed in absorbance mode at 286 nm. The method was validated for linearity, accuracy, and precision. Oxaprozin was subjected to acidic and alkaline hydrolysis. The degradation products were well resolved from the pure drug with significantly different R F values. LC-MS-MS analysis revealed that oxaprozin decomposes to produce 1,2-diphenylethanol, 4-iminobutanoic acid, and propan-1-imine.
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%.
The application of a simple, selective, precise, and accurate thinlayer chromatographic method for quantification of l-carnitine in dietary food supplements, including drinks, capsules, and tablets, was reported. The high-performance thin-layer chromatography (HPTLC)-cellulose plates as stationary phase, and mixture: methanol-water-glacial acetic acid (10:2:0.1 ν/ν) as mobile phase were chosen. The chromatograms were analyzed densitometrically in the maximum absorption at 420 nm, after ninhydrin-based derivatization reaction. The analytical procedure has been validated in terms of basic parameters, such as linearity, precision, and accuracy. The developed method is characterized by LOD sensitivity of 2.51 μg per spot, as well as LOQ for 7.61 μg per spot and high accuracy established by recovery studies between 99.50% and 103.60 % with good precision (RSD below 1.55%). Presented TLC method illustrated suitability for routine qualitative and quantitative analyses of l-carnitine in dietary supplements.
