COMPARISON OF THE DETECTION AND QUANTITATIVE LIMITS OF HYDROCORTISONE ACETATE IN DIFFERENT CHROMATOGRAPHIC CONDITIONS IN TLC

Influence of Chromatographic Conditions on LOD and LOQ of Fluoxetine and Sertraline Analyzed by TLC-Densitometric Method

This research introduces the analysis of fluoxetine and sertraline by means of the TLC-densitometric method. They provide information on LOD and LOQ under various chromatographic conditions. The study used adsorption (NPTLC) and partition (RPTLC) thin-layer chromatography in combination with a densitometric analysis. Four types of chromatographic plates precoated with: silica gel 60 F254, silica gel 60, silanized silica gel 60 F254 (RP-2), and a mixture of silica gel 60 and kieselguhr F254, as well as three mobile phases: chloroform + methanol + ammonia (9:1:0.4, v/v/v), chloroform + methanol + glacial acetic acid (5:4:1, v/v/v), and acetone + toluene + ammonia (10:9:1, v/v/v), were used in NPTLC. RP-18F254 and silanized silica gel 60 F254 (RP-2) plates and four mobile phases: methanol + water (10:0 and 9:1, v/v), acetone + water (10:0 and 9:1, v/v), were used in RPTLC. The lowest LOD and LOQ values for fluoxetine were obtained using a silanized silica gel 60 F254 (RP-2) with acetone + toluene + ammonia (10:9:1, v/v/v) in NPTLC, and with a silanized silica gel 60 F254 (RP-2) in combination with methanol + water (10:0, v/v) in RPTLC. The lowest LOD and LOQ values of sertraline were obtained using a silica gel 60 with acetone + toluene + ammonia (10:9:1; v/v/v) in NPTLC. The smallest amount of sertraline was detected on the silanized silica gel 60 F254 plate in combination with methanol + water (9:1, v/v) in RPTLC. The obtained results provide important information that can give a good basis and set the direction for further, more detailed research; the results can also benefit other researchers who analyze fluoxetine and sertraline with the TLC technique in model systems (testing standards) as well as in drug and biological samples.

Analytical method development and determination of hydrocortisone acetate and fusidic acid simultaneously in cream formulation, by reversed-phase HPLC

In this study, an accurate, simple, economical, precise and reproducible reversed-phase HPLC method was developed for the estimation of fusidic acid and hydrocortisone acetate, according to the International Conference on Harmonization guidelines, in a cream formulation. Chromatographic separation was achieved by isocratic elution, on a Shimadzu reversed-phased high-pressure liquid chromatography instrument, equipped with a C₁₈ column (150 × 4.6 mm, 5 μm) and UV detector at 225 nm wavelength, using acetonitrile and 0.05% trifluoroacetic acid (60:40), as a mobile phase and diluent, at flow rate 2 ml/min and an injection volume of 20 μl. The calibration curves were acquired with concentration range 80-120% and mean percentage recoveries for hydrocortisone acetate and fusidic acid were 100.14 and 100.81%, respectively. The limits of detection was obtained as 6.0667 and 6.807 μm ml^-1 and the limits of quantification were 20.204 and 20.628 μm ml^-1 for hydrocortisone acetate and fusidic acid, respectively. All of the validation parameters were within the acceptance criteria, as per International Conference on Harmonization requirements, for hydrocortisone acetate and fusidic acid. This method was found to be validated, simple, rapid and applicable for the simultaneous estimation of hydrocortisone acetate and fusidic acid by reversed-phased high-pressure liquid chromatography, for routine analytical testing in quality control, with a run time of 8 min.

Estimating Limits of Detection and Quantification of Ibuprofen by TLC-Densitometry at Different Chromatographic Conditions

Ibuprofen is one of the best-known nonsteroidal anti-inflammatory and analgesic drugs. Following the previous work, the current study is focused on estimating the effect of different chromatographic conditions on the sensitivity of thin-layer chromatography in combination with UV densitometry, i.e., the detection and quantification of ibuprofen in a wide range of its concentrations including the lowest limits of detection (LOD) and quantification (LOQ). For this purpose, a reliable and easy-to-use calculation procedure for LOD and LOQ determination is presented in this work. In addition, the impact of type plates and mobile phase composition on the LOD and LOQ, respectively, of this active substance is accurately described. The results of detection and the quantification level of ibuprofen obtained under applied chromatographic conditions confirmed the utility of silica gel plates as well as silica gel bonded phases (i.e., reversed-phase (RP) plates) in the thin-layer chromatography (TLC)-densitometric analysis of ibuprofen at a low level, i.e., from several nanograms (below one microgram) to a few micrograms/spot. Among all chromatographic systems tested, the best are those consisting of silica gel 60F254 plates with concentrating zone (1.05583) and the mixture of n-hexane:ethyl acetate:glacial acetic acid in ratio 36:12:2 (v/v/v) as well as RP plates, i.e., RP-18F254 aluminum plates developed with methanol:water in volume composition 40:10 (v/v). These chromatographic systems allowed quantifying ibuprofen in the amount of 0.229 µg/spot and 0.228 µg/spot, which is less than 1 µg/spot. It can be stated that different chromatographic systems in combination with UV densitometric scanning at 224 nm proposed in this work can be successfully applied for the cost-effective and sensitive determination of ibuprofen as a widely used drug component as well as a residual in domestic wastewater. It was found that the modification of silica gel as well as the layer thickness of unmodified or modified silica gel 60 can influence the quality of chromatograms and the detection/quantification of ibuprofen in both normal phase (NP) and RP systems. Therefore, to obtain the best possible LOD and LOQ values of ibuprofen with precoated layers, suitable mobile phase and chromatographic plates are required.

Influence of Different Chromatographic Conditions on the Level of Detection and Quantitation of Spironolactone by means of TLC-Densitometry

The aim of this study was to estimate the influence of different chromatographic conditions on the limits of detection and limits of quantitation (LODs and LOQs) of spironolactone by means of TLC-densitometry under different chromatographic conditions. A comparison of results obtained showed that the choice of appropriate chromatographic conditions for NP-TLC and RP-TLC analysis with densitometry could effectively decrease the LODs and LOQs of spironolactone. Of all chromatographic systems tested, the best was the one comprising chromatographic plates precoated with a mixture of silica gel 60, kieselguhr F₂₅₄, and mobile phase A (n-hexane-ethyl acetate-glacial acetic acid, 24.5 : 24.5 : 1, v/v/v). The estimated average LOD and LOQ values were 0.034 and 0.103 μg/spot, respectively. This indicates that the described procedure is sufficiently sensitive for the identification and quantification of spironolactone alone. Thereby, the simple and cost-effective TLC-densitometric method can be utilized for the routine quality control of spironolactone in bulk drugs as well as in simple pharmaceutical formulations.

Comparative study of two different chromatographic approaches for quantitation of hydrocortisone acetate and pramoxine hydrochloride in presence of their impurities

In the present study, we compare the performance of two reversed-phase liquid chromatographic approaches using different eluents either conventional hydro-organic eluent or micellar one for simultaneous estimation of hydrocortisone acetate and pramoxine hydrochloride in presence of their degradants and process-related impurities; hydrocor-tisone and 4-butoxyphenol, respectively. For conventional reversed-phase liquid chromatography (RPLC), separation of the studied compounds was completed on an Inertsil ODS 3-C18 column (150 mm × 4.6 mm, 5 μm particle size) with a mobile phase consists of 50 mM phosphate buffer (pH 5.0): acetonitrile (50: 50, v/v). For micellar liquid chromatography (MLC), an Eclipse XDB-C8 column (150 mm × 4.6 mm, 5 μm particle size) was chosen for the separation with a green mobile phase consists of 0.15 M sodium dodecyl sulfate, 0.3% triethylamine and 10% n-butanol in 20 mM orthophosphoric acid (pH 5.0). Both methods were extended to analyze hydrocortisone acetate and pramoxine hydrochloride in their co-formulated cream. RPLC was superior to MLC with regard to sensitivity for the estimation of impurities. While, MLC represents an eco-friendly, less hazardous and biodegradable approach. Furthermore, the direct injection of the cream to the system without the need to laborious samples pretreatment, excessive amount of analysis time and/or use of large amount of toxic organic solvents is one of the outstanding advantages of MLC.

A Validated TLC-Densitometric Method for the Determination of Mesterolone in Bulk Material and in Tablets

Mesterolone is a synthetic androgenic steroid indicating a weak anabolic activity. A new, simple in use, and economical TLC-densitometric method in normal phase system (NP-TLC) has been developed and validated for the identification and quantitative determination of mesterolone in bulk drug and in tablet formulation. NP-TLC analysis was performed on aluminium plates precoated with silica gel 60F₂₅₄ as the stationary phase using chloroform-acetone (40 : 10, v/v) as mobile phase. Densitometric analysis was carried out at λ = 745 nm after staining with phosphomolybdic acid. These conditions were found to give visible (dark blue) spot and sharp peak, respectively, for mesterolone at R_F  0.75 ± 0.02 and enabled satisfactory separation of mesterolone from its related substance (potential impurity). The proposed NP-TLC-densitometric method was validated for specificity, linearity, precision, accuracy, robustness, and sensitivity according to ICH guideline and other validation requirements. The limit of detection (LOD) and limit of quantification (LOQ) were 61.0 ng·spot⁻¹ and 184.0 ng·spot⁻¹, respectively. The percent content of mesterolone in marketed tablet formulation was found to be 99.40% of label claim. The developed TLC-densitometric method can be successfully used in quality control of mesterolone in bulk material and also tablet formulation.