Determination of tocopheryl acetate and ascorbyl tetraisopalmitate in cosmetic formulations by HPLC.

A rapid HPLC method was developed for the assay of tocopheryl acetate and ascorbyl tetraisopalmitate in cosmetic formulations. The validated method was applied for quantitative determination of these vitamins in simulated emulsion formulation. Samples were analysed directly on a RP-18 reverse phase column with UV detection at 222 nm. A mixture of methanol and isopropanol (25 : 75 v/v) was used as mobile phase. The retention time of tocopheryl acetate and ascorbyl tetraisopalmitate were 3.0 min and 5.9 min, respectively. Recovery was between 95% and 104%. In addition, the excipients did not interfere in the analysis. The method is simple, reproducible, selective and is suitable for routine analyses of commercial products.

Validation of a HPLC method for simultaneous determination of five sunscreens in lotion preparation.

The aim of this research was to develop and validate a high-performance liquid chromatographic (HPLC) method for simultaneous determination of five sunscreens, namely benzophenone-3 (B-3), butyl methoxydibenzoylmethane (BM), octyl methoxycinnamate (OM), octyl salicylate (OS) and homosalate (HS). The separation and quantitative determination was made by HPLC at 40 +/-1 degrees C with a gradient elution from 10% to 100% mobile phase B in mobile phase A. The gradient liquid chromatographic system constituted of mobile phase A [acetonitrile : water (10 : 90 v/v)] and mobile phase B [acetonitrile : water (90 : 10 v/v)], at a flow rate of 1.0 mL min(-1) and ultraviolet detection at 310 nm. The separation was obtained with two Waters reversed phase columns: Novapack C-18 and Symmetry((R)) C-18 connected in series. All sunscreens were efficiently separated within 17 min. The coefficient of correlation and average recovery for B-3, BM, OM, OS and HS were 0.9798 and 98.5%, 0.9672 and 98.8%, 0.9922 and 99.1%, 0.9961 and 98.9% and 0.9909 and 99.4% respectively. The relative standard deviations obtained were between 1.07% and 2.44%. The excipients did not interfere in the analysis. The results showed that the proposed method could be used for rapid and simultaneous determination of B-3, BM, OM, OS and HS in sunscreen lotions with precision, accuracy and specificity.

Development and validation of a HPLC and a UV derivative spectrophotometric methods for determination of hydroquinone in gel and cream preparations.

A high performance liquid chromatographic (HPLC) and a ultraviolet derivative spectrophotometric (UVDS) methods were developed and validated for the quantitative determination of hydroquinone (HQ) in gels and creams containing this compound as a unique active principle. Validation parameters such as linearity, precision, accuracy, specificity, limit of detection (LOD) and limit of quantitation (LOQ) were determined. HPLC was carried out by reversed phase technique on a RP-18 column with a mobile phase composed of methanol and water (20:80, v/v). The linearity in the range of 6.0-30.0 microg/mL present a correlation coefficient (r) of 0.9999, calculated by least square method. The LOD and LOQ were 0.08 and 0.26 microg/mL, respectively. Based on the preliminary spectrophotometric profile of HQ, a signal at 302.0 nm of the first derivative spectrum (1D302.0) was found adequate for validation. The linearity between signal 1D302.0 and concentration of HQ in the range of 10.0-26.0 microg/mL in sulfuric acid (0.1N) present a correlation coefficient (r) of 0.9999. The LOD and LOQ were 0.14 and 0.46 microg/mL, respectively. Statistical analysis by t- and F-tests, showed no significant difference at 95% confidence level between the two proposed methods.

Validation of a high performance liquid chromatography method for sunscreen determination in cosmetics.

The aim of this research was the development and validation of a high performance liquid chromatography (HPLC) method for the simultaneous and quantitative determination of benzophenone-3, octyl methoxycinnamate and octyl salicylate contained in sunscreen emulsions. The separation and quantitative determination was achieved using a LiChrospher((R)) 100 RP-18 (5 microm) Merck column, a mobile phase constituted of methanol/water (85/15, v/v), a flow-rate of 1.0 mL min(-1) and UV detection at 310 nm. The correlation coefficients and percentage of recovery for benzophenone-3, octyl methoxycinnamate and octyl salicylate were 0.9999 and 99.46%; 0.9995 and 98.85%; 0.9998 and 98.84%, respectively. The relative standard deviations (RSD) for commercial samples were between 0.50 and 0.70%.

Enantiomeric separation and quantitative determination of propranolol in tablets by chiral high-performance liquid chromatography.

This work reports an application of chiral high-performance liquid chromatography (HPLC) in the separation and quantitative determination of propranolol isomers in tablets. The isomers were separated using a Chiralcel OD column (250 x 4.6 mm, 10 microm) with a mobile phase of hexane:ethanol (75:25 v/v) at a flow rate of 0.7 ml/min and ultraviolet detection at 280nm. The coefficient of variation and average recovery of (R)-isomer for samples A, B, C, and D were 0.72% and 100.30%, 0.67% and 99.40%, 0.62% and 99.76%, and 0.70% and 99.68%, respectively. The coefficient of variation and average recovery of (S)-isomer for samples A, B, C, and D were 0.74% and 99.62%, 0.64% and 100.27%, 0.71% and 99.99%, and 0.70% and 99.72%, respectively.

Development and validation of a chiral liquid chromatographic method for the determination of atenolol and metoprolol enantiomers in tablet preparations.

Atenolol (AT) and metoprolol (MT) are predominantly used in the treatment of angina pectoris, certain arrhythmias, systemic hypertension, and several other cardiovascular disorders. Both compounds are produced commercially in the racemic form, although the S-form is responsible for the desired biological effect. This paper describes a simple, rapid, precise, and accurate method for separating the enantiomers of AT and MT. AT isomers are separated by using a Chiralcel OD column (250 x 4.6 mm, 10 microm), hexane-ethanoldiethylamine-acetic acid (60 + 40 + 0.2 + 0.2, v/v/v/v) as the mobile phase, and a flow rate of 1.0 mL/min. MT isomers are separated by using a mobile phase with the same components in the following proportions (40 + 60 + 0.2 + 0.2, v/v/v/v) and a flow rate of 0.8 mL/min. Ultraviolet detection was at 276 nm for both analytes. The coefficients of variation (CVs) and average recoveries (ARs) for the R-enantiomers in samples A, B, C, D, and E were 1.15 and 101.06%, 0.74 and 99.25%, 1.05 and 102.57%, 0.84 and 101.57%, and 0.86 and 98.62%, respectively. The CVs and ARs for the S-enantiomers in samples A, B, C, D, and E were 1.33 and 98.87%, 0.99 and 100.76%, 1.17 and 101.69%, 1.26 and 100.39%, and 1.40 and 99.39%, respectively. The standard curves of R-AT, S-AT, R-MT, and S-MT showed good linearity over the concentration range studied with correlation coefficients of 0.9991, 0.998, 0.9988, and 0.999, respectively.

Enantiomeric separation and quantitative determination of atenolol in tablets by chiral high-performance liquid chromatography.

The separation and quantitative determination of atenolol isomers by chiral high-performance liquid chromatography (HPLC) are described. Atenolol isomers were separated using a Chiralcel OD column (250 x 4.6 mm, 10 microns); the mobile phase was hexane-ethanol-diethylamine (75:25:0.1 v/v/v); ultraviolet detection was at 276 nm; and flow rate was 0.7 ml/min. The coefficient of variation and average recovery of (R)-isomer were 0.60% and 100.37%, respectively, for sample A and 0.69% and 100.63%, respectively, for sample B. The coefficient of variation and average recovery of (S)-isomer were 0.59% and 100.33%, respectively, for sample A and 0.63% and 99.78%, respectively, for sample B.

Simultaneous determination of thiabendazole and mebendazole in tablets by high-performance liquid chromatography.

Reversed-phase high performance liquid chromatography using an RP 18 column (4 x 125 mm), tetrahydrofuran-acetonitrile-0.5% formic acid (5:25:70, v/v/v) as mobile phase and UV detection at 254 nm enabled the simultaneous determination of thiabendazole (TZ) and mebendazole (MZ) in tablets. The method showed linearity over 4.0 to 40.0 micrograms TZ/ml and 6.0 to 60.0 micrograms MZ/ml. The correlation coefficient r was .9999 for both TZ and MZ. The coefficient of variation (CV) was 0.59-0.80% for TZ and 0.49-0.67% for MZ. The average recovery was 100.54-101.17% for TZ and 100.35-101.13% for MZ. The excipients of the tablets did not interfere in the proposed method. The developed method is precise, accurate, and selective for the determination of both benzimidazoles analyzed.

Determination of methotrimeprazine in pharmaceutical preparations by visible spectrophotometry.

A spectrophotometric method is described for determination of methotrimeprazine (levomepromazine). The aim of this work was to develop a simple, rapid, precise, and accurate visible spectrophotometric method for determination of methotrimeprazine in tablet, oral solution, and injection. The method is based on methotrimeprazine reaction with bromophenol blue, resulting in a stable, light yellow-green ion-pair complex that, after extraction with chloroform, presented maximum absorption at 409 nm. Beer's law was obeyed in the concentration range from 5.0 to 25.0 micrograms/ml. The proposed standardized method was applied to commercially available and simulated samples. The accuracy of the method was confirmed by recovery tests.

Determination of betamethasone dipropionate and salicylic acid in pharmaceutical preparations by high-performance liquid chromatography.

The simultaneous determination of betamethasone dipropionate (BD) and salicylic acid (SA) in both ointment and topical solution was developed using high-performance liquid chromatography (HPLC). The method was standardized using a LiChrospher 100 RP-18 (125 x 4 mm, 5 microns) column, acetonitrile-tetrahydrofuran-acetic acid 1% (25:20:55 v/v), apparent pH 3.3, as mobile phase, and UV detection at 254 nm. The peak area response versus concentration was linear in a concentration range from 5.0 to 50.0 micrograms/ml of BD and from 20.0 to 200.0 micrograms/ml of SA. The correlation coefficients were 0.9997 for BD and 0.9987 for SA, and the relative standard errors of estimates were 1.38% for BD and 3.27% for SA. The coefficient of variation and the recovery average were, respectively, 0.41-1.15% and 100.09% for BD, and 0.57-0.95% and 99.79% for SA.

Visible spectrophotometric and first-derivative UV spectrophotometric determination of rifampicin and isoniazid in pharmaceutical preparations.

Two methods are described for the determination of rifampicin and isoniazid in mixtures by visible spectrophotometry and first-derivative ultraviolet spectrophotometry. The absorbance at 475 nm in buffer solution pH 7.4 was employed to determine rifampicin after applying the three-point correction technique between 420 and 520 nm, while the amplitude of the first-derivative spectrophotometric spectrum at 257 nm in HCl 0.012 M was selected for the determination of isoniazid. The methods are rapid, simple and do not require any separation step. The recovery average was 99.03% for rifampicin and 100.01% for isoniazid. The methods were applied to determine the two compounds in commercial capsules and compared with the official method of the USP XXIII with good agreement between the results.

[Stability of oral rehydration solutions in various packing materials]. / Estabilidade de sais de reidrata ção oral em diferentes tipos de embalagem.

The aim of this research was to provide data to select an ideal packing material to preserve the integrity of oral rehydration salts (ORS), a therapeutic formulation that is essential in developing countries. Previous research had verified that water is the factor that most affects ORS stability. For this research, a pharmaceutical industry prepared an ORS batch that was packed in six different types of packing materials. The humidity determination was made after storage of samples during 36 weeks at room temperature, at room temperature with 76% relative humidity, and at 40 degrees C with 80% relative humidity. The moisture in the samples was measured at pre-determined intervals using methods like loss on drying at 50 degrees C and the Karl Fischer method. The results indicated that the most efficient packing material was composed of 18g polyester, 35 g aluminum, and 50 g polyethylene (packing material no. 6).

Stability of phenobarbital sodium in liquid pharmaceutical preparations.

Shelf-lives of liquid pharmaceutical preparations (injectable and oral solution) containing phenobarbital sodium, commercially available in Brazil, were predicted by accelerated stability test using isothermal method (at 37 degrees C, 50 degrees C and 75 degrees C). Data obtained in high temperature studies using Arrhenius relation were applied to predict shelf-lives at room temperature. The shelf-lives were calculated by linear regression analysis. UV difference spectrophotometry was used for phenobarbital determination. Thin-layer chromatography was used for separation and identification of phenylethylacethylurea, the main degradation product of phenobarbital.

First-derivative spectrophotometric determination of salbutamol in pharmaceutical preparations.

The development of a first-order derivative spectrophotometric assay of salbutamol as a single-component and in combination with beclomethasone dipropionate in pharmaceutical formulations is described. The method eliminates the interference of tablet excipients and allows the determination of both components without their previous separation. The precision of the method for the assay of salbutamol in tablets was 1.0% with an average recovery of 98.8%. In the assay of the two-component preparation, the precision was 1.1%, with average recoveries for salbutamol of 99.3% and for beclomethasone dipropionate of 99.4%.

Doseamento do cloridrato de prometazina en medicamentos. / Determination of promethazine hydrochloride in drugs

Amostras de medicamentos, contendo cloridrato de prometazina, foram analisadas por dois metodos oficiais e por un metodo espectrofotometrico baseado na diferenca de absorcao no ultravioleta entre una solucao de prometazina oxidada e outra nao oxidada Nao foram observadas diferencas significativas entre os resultados obtidos pelos tres metodos.A espectrofotometria diferencial e simples, rapida e aplicavel a todas as formas farmaceuticas, sendo economicamente mais favoravel que os metodos oficiais

Estudo da estabilidade da vitamina D por cromatografia liquida de alto desempenho. / Stability studies of vitamin D by high performance liquid chromatography

Estudou-se a estabilidade das vitaminas D2 e D3 por cromatografia liquida de alto desempenho (CLAD). Varias amostras das duas vitaminas foram pesadas e submetidas a diferentes condicoes de temperatura e umidade relativa. De tempos em tempos estas amostras, dissolvidas em cloroformio, foram cromatografadas.Os teores foram determinados por comparacao com padroes injetados nas mesmas concentracoes. A decomposicao foi tambem acompanhada por cromatografia em camada delgada

Simultaneous determination of vitamins A and D in a dosage forms by high pressure liquid chromatography.

Vitamins A and D were determined simultaneously in oily solutions, ointments, and elixirs, but only vitamin A could be determined in capsules. Samples were saponified with KOH in isopropanol-water, using hydroquinone as antioxidant, and extracted with ether-petroleum ether (1 + 1). After evaporation of solvent, residues were dissolved in isopropanol. Vitamins in these solutions were determined by reverse phase high pressure liquid chromatography, using methanol-water as mobile phase and detection at 254 nm. The reproducibility, using external standards, was 1.6-2.5% and 1.2-3.8% for vitamins A and D, respectively.