ABSTRACT
The article reports on low-temperature high-rate sputtering of hydrophilic transparent TiO2thin films using dc dual magnetron (DM) sputtering in Ar + O2mixture on unheated glass substrates. The DM was operated in a bipolar asymmetric mode and was equipped with Ti(99.5) targets of 50 mm in diameter. The substrate surface temperature Tsurfmeasured by a thermostrip was less than 180 °C for all experiments. The effect of the repetition frequency frwas investigated in detail. It was found that the increase of frfrom 100 to 350 kHz leads to (a) an improvement of the efficiency of the deposition process that results in a significant increase of the deposition rate aDof sputtered TiO2films and (b) a decrease of peak pulse voltage and sustaining of the magnetron discharge at higher target power densities. It was demonstrated that several hundreds nm thick hydrophilic TiO2films can be sputtered on unheated glass substrates at aD = 80 nm/min, Tsurf < 180 °C when high value of fr = 350 kHz was used. Properties of a thin hydrophilic TiO2film deposited on a polycarbonate substrate are given.
ABSTRACT
A novel reversed-phase HPLC method for the simultaneous determination of active component terbinafine, its one impurity 1-methylaminomethylnaphtalene and three degradation products, beta-terbinafine, Z-terbinafine and 4-methyl-terbinafine occurring in pharmaceutical formulations after long-term stability tests, was developed and validated using propylparaben as an internal standard. The chromatographic separation was performed on a NUCLEOSIL 100-5-CN column, mobile phase for separation of all compounds consisted of a mixture of tetrahydrofurane, acetonitrile and citrate buffer pH 4.50 (10:20:70,v/v/v). The analysis time was less than 32 min at flow-rate of 0.8 ml min(-1). UV detection was performed at 226 nm. The method was validated and system suitability parameters were investigated. Method robustness and short-term standard solution stability were verified. Limits of detection for terbinafine degradation products/impurity were from 0.023 to 0.098 microg ml(-1), limits of quantitation were from 0.078 to 0.327 microg ml(-1). The method was applicable for routine determination of terbinafine and all its found impurities of similar structure with sufficient selectivity, precision and accuracy.
ABSTRACT
A novel reversed-phase high-performance liquid chromatographic method with UV spectrophotometric detection was developed and validated for the determination of compounds in topical cream. The method describes determination of active component hydrocortisone acetate (HCA), its degradation products hydrocortisone (HC) and cortisone acetate (occurring in formulation after long-term stability tests) and two preservatives presented in the cream-methylparaben and propylparaben, using dexamethasone as an internal standard. The chromatographic separation was performed on a 5 microm SUPELCO Discovery C18 125 x 4-mm ID column. The optimised mobile phase for separation of all the compounds consists of methanol, acetonitrile and water (15:27:58, v/v/v), with the analysis time less than 13 min. The method was applicable for routine analysis (assays and stability tests) of active compound HCA, preservatives and degradation products in pharmaceutical product--topical cream Hydrocortizone cream 1%.
Subject(s)
Emollients/analysis , Hydrocortisone/analogs & derivatives , Hydrocortisone/analysis , Parabens/analysis , Technology, Pharmaceutical/methods , Administration, Topical , Chromatography, High Pressure Liquid/methods , Emollients/chemistry , Hydrocortisone/chemistry , Parabens/chemistryABSTRACT
A novel reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed and validated for the determination of active component triamcinolone acetonide, its degradation product triamcinolone (occurring in formulation after long-term stability tests) and two preservatives presented in the cream-methylparaben and propylparaben, using hydrocortisone as an internal standard. The chromatographic separation was performed on a Supelco Discovery C18 column; the mobile phase for separation of all compounds consists of a mixture of acetonitrile and water (40:60 v/v). The analysis time was less than 9 min, at a flow rate of 0.6 mL min(-1) and detection at 240 nm. The method was found to be applicable for routine analysis (stability tests, homogeneity) in the pharmaceutical product topical cream Triamcinolon cream 0.1%.
