Anna Kwiecień

Simultaneous identification and quantitative determination of neomycin sulfate, polymixin B sulfate, zinc bacytracin and methyl and propyl hydroxybenzoates in ophthalmic ointment by TLC

A thin layer chromatographic-densitometric method for identification and quantitation of neomycin sulfate, polymixin B sulfate, zinc bacytracin and auxiliary substances (methyl and propyl hydroxybenzoates) in ophthalmic ointment was developed. To separate these constituents the silica gel coated TLC plates and two mobile phases were used. The suitable mobile phases were: methanol-n-butanol-ammonia 25%-chloroform (14:4:9:12, v/v/v/v) for determination of antibiotics and n-pentane-glacial acetic acid (66:9, v/v) for methyl and propyl hydroxybenzoates. The antibiotic chromatograms were detected by using ninhydrin ethanol solution, while densitometric measurements were made at lambda = 550 nm. Hydroxybenzoates were identified by UV measurements at lambda = 260 nm. The constituents under consideration were well separated at sufficient detection level. The recovery for all constituents ranged from 98.08% to 104.95%.

Application of densitometry for determination of beta-adrenergic-blocking agents in pharmaceutical preparations

A chromatographic-densitometric method has been established for identification and quantitation of selected beta-adrenergic-blocking agents in pharmaceutical preparations. Retention factors, RF, and characteristic absorption spectra of 11 drugs chromatographed on silica gel 60 F254 HPTLC plates with six mobile phases were used for identification. Quantitation and validation of the method was performed for atenolol, acebutolol, propranolol, and bisoprolol using chloroform-methanol-ammonia, 15 + 7 + 0.2 (v/v), as mobile phase. UV densitometric measurements were performed at the wavelength of maximum absorption. Pharmaceutical preparations used in medicine and from a variety of manufacturers were analyzed and the method shown to be sufficiently sensitive for analysis of these samples. The limits of detection and determination ranged from 30 to 400 ng and recovery was from 97.14 to 102.18%. The precision of the method, described by the equation y = xmean ± 2S, is good and the range of linearity is wide - from 0.020 to 0.250% for individual constituents.

Stability of Atenolol, Acebutolol and Propranolol in Acidic Environment Depending on its Diversified Polarity

The main objective of this research was to investigate the relationship between the polarity of atenolol, acebutolol, and propranolol described by logP and kinetic and thermodynamic parameters characterizing their degradation process in acidic solution. Hydrolysis was carried out in hydrochloric acid at molal concentrations of 0.1 mol/L, 0.5 mol/L, and 1 mol/L for 2 hr at 40°C, 60°C, and 90°C. Chromatographic-densitometric method was used for the determination of drugs under investigation. The identification of degradation products was carried out by using 1H NMR. The degradation processes that occurred in drugs under investigation are described with kinetic parameters (k, t0.1, and t0.5) and energy of activation (Ea). It has been found that the stability of drugs increases toward lipophilic propranolol in the assumed experimental model. The rate constants k decrease, contrary to t0.1, t0.5, and Ea, which vary comparably to logP, thus increasing from the most hydrophilic atenolol, through acebutolol, of lower polarity, to the most lipophilic propranolol. This study demonstrated that the stability of chosen beta-adrenergic blocking agents increases with their lipophilicity.

Simultaneous Determination of Fusidic Acid, m‐ and p‐Hydroxybenzoates and Butylhydroxyanisole by TLC with Densitometric Detection in UV

Abstract A thin‐layer chromatography (TLC)‐densitometric method has been developed for the identification and quantification of fusidic acid (FA) (RF=0.53), methyl hydroxybenzoate (MHB) (RF=0.64), propyl hydroxybenzoate (PHB) (RF=0.72), and butylated hydroxyanisol (BHA) (RF=0.77), which are the components of a dermatological ointment. To separate these constituents, n‐hexane‐ethyl acetate‐glacial acetic acid (6∶3∶1, v/v/v) has been used as the mobile phase and silica gel 60 F254 TLC plates as the stationary phase. To detect the spots on chromatograms, densitometric measurements at three different wavelengths were carried out, i.e., 240 nm (FA), 260 nm (MHB, PHB), and 290 nm (BHA), leading to increased selectivity and decreased interferences of the peaks. The results of the model drug examination were characterized by good precision, accuracy, and high sensitivity.

TLC-Densitometric Determination of Azithromycin in Pharmaceutical Preparations

A thin-layer chromatographic method with densitometric detection has been established for quantification of azithromycin in pharmaceutical preparations. Silica gel plates with fluorescence indicator F254 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 RF 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 fig/zone, r - 0.9965), and high precision, accuracy (mean percentage recovery 102.73%), and specificity.

Simultaneous Determination of Acetylsalicylic Acid, Hydrochlorothiazide, Enalapril, and Atorvastatin in a Polypill-Based Quaternary Mixture by TLC

A new chromatographic-densitometric method has been developed for the qualitative and quantitative determination of the active ingredients in a simulated mixture corresponding to the PolyIran polypill, composed of acetylsalicylic acid, hydrochlorothiazide (HCT), enalapril (ENA), and atorvastatin (ATR), whose efficacy in the treatment and prevention of cardiovascular disease has been documented in clinical trials. Chromatographic separation was performed using TLC silica gel 60 plates with fluorescent indicator F254 as the stationary phase and a mixture of n-hexane-ethyl acetate-methanol-water-acetic acid (8.4 + 8 + 3 + 0.4 + 0.2, v/v/v/v/v) as the mobile phase. Densitometric measurements were carried out at λ = 210 nm when determining ENA and at λ = 265 nm in the case of the other drugs. Peaks of examined substances were well separated in the recorded chromatograms, enabling the evaluation of the results in terms of both qualitative and quantitative analysis. The method was specific for the analyzed components and was characterized by high sensitivity. The LOD was between 0.043 and 0.331 μg/spot, and LOQ was between 0.100 and 0.942 μg/spot. Recovery was in the range of 97.02-101.34%. The linearity range was broad and ranged from 0.600 to 6.000 μg/spot for acetylsalicylic acid, from 0.058 to 1.102 μg/spot for HCT, from 0.505 to 6.560 μg/spot for ENA, and from 0.100 to 1.000 μg/spot for ATR. The method was characterized by good precision, with RSD values that ranged from 0.10 to 2.26%.