High-performance liquid chromatographic determination of simvastatin in medical drugs

A simple and rapid HPLC method for the determination of simvastatin using a C18-Hypersil column and acetonitril-phosphate buffer-methanol (5: 3: 1, v/v/v) as a mobile phase with detection at 230 nm was proposed. Commercial pharmaceutical tablets were analyzed with a linear range for simvastatin up to 1.884 mg % and a regression coefficient of 0.9995. The method is found to be precise, accurate, reliable, and selective. The text was submitted by the authors in English.     

High-performance liquid chromatographic determination of alpha-tocopheryl nicotinate in cosmetic preparations.

alpha-Tocopheryl nicotinate (alpha-TN) accelerates blood circulation and stimulates hair follicle cells, hence it is an active ingredient in a broad range of cosmetic products. A reversed-phase high-performance liquid chromatographic method was developed to determine alpha-TN in cosmetic preparations with alpha-tocopheryl acetate as internal standard. The method was found to be rapid, precise and specific.     

High-pressure liquid chromatographic determination of benfurodil hemisuccinate in blood and urine (author's transl)

A sensitive and reliable method for quantitative determination of benfurodil hemisuccinate and benfurodil in plasma by high-pressure liquid chromatography on a Zorbax SIL column with a mean particle size of 7 micrometer and UV detection at 254 nm is described. Benfurodil hemisuccinate is stable in plasma but not in aqueous solutions. This is explained by its great fixation to plasma proteins which has been shown by equilibrium dialysis.     

High-performance liquid chromatographic separation of cobalamins

Physiological cobalamins were separated by means of high-performance liquid chromatography (HPLC). Optimal conditions for elution of methylcobalamin, adenosylcobalamin, hydroxycobalamin and cyanocobalamin were determined. Excellent separation and resolution of these physiological cobalamins by HPLC were achieved. In addition, several cobalamin analogues were also studied and shown to be separable from the physiological forms. HPLC provides a rapid, sensitive, reproducible means of characterizing physiological cobalamins.     

High-performance liquid chromatographic separation of enantiomeric amines

Summary Separations of twelve different racemic amines were studied by high-performance liquid chromatography (HPLC) in several column-solvent combinations. Relative retentions, which show some dependence upon the substitution at the asymmetric centers, are reported for the amines which were examined as the (+)-10-camphorsulfonamides.     

High-performance liquid chromatographic determination of prostacyclin.

A high-performance liquid chromatographic method for the analysis of prostacyclin using a laboratory prepared reversed-phase column packing is described. A relative standard deviation of less than 1% was obtained for ten replicate injections. The system resolves prostacyclin from its hydrolysis product, 6-oxo-prostaglandin F1 alpha and from other prostaglandins present as impurities. These can be estimated to levels of approximately 0.5%. The separation of other unrelated prostaglandins by this method is briefly reported.     

High-performance liquid chromatographic determination of kanamycin.

A fast, selective, and precise liquid chromatographic method for simultaneous, independent determination of kanamycins A and B is described. Sample components are separated on a pellicular cation exchanger and monitored by fluorescence using post-column on-line derivatization. Less than 0.35 mug of kanamycin B can be detected in as much as 7 mug kanamycin A injected. The detection limit for kanamycin A is less than 20 ng injected. Reproducibility of the entire chromatographic system is about 1% (2 theta) based upon repeated injections of standards. Precision of repeated process sample preparation is about 6% (2 theta). Chromatographic analysis time is less than 15 min per sample.     

High-performance liquid chromatographic determination of bleomycins.

A rapid and specific ion-pair reversed-phase high-performance liquid chromatographic method was developed for the determination of bleomycins. The use of 5-microns particles of less adsorptive reversed-phase packings and sodium perchlorate as ion-pairing reagent permitted a short analysis time and the transferability of the separations on different batches of the reversed-phase materials. The detection sensitivity and precision of the method demonstrated that the system is suitable for routine analysis.     

High-performance liquid chromatographic separation of polyolefin antioxidants and light-stabilisers

Summary A scheme was devised for the identification of 22 common antioxidants and light-stabilisers in polyolefins. The separation of these stabilisers was performed by isocratic reversed phase high-performance liquid chromatography on a RP-18 column. Three different separation conditions have been used: the mobile phase composition was 100% acetonitrile (MeCN), 90/10 meCN/H₂O and 80/20 MeCN/H₂O. The UV₂₅₄/UV₂₈₀ ratio and the elution time of each stabiliser were determined for these three mobile phase compositions. The values of UV₂₅₄/UV₂₈₀ ratios may be used together with the retention time values for the identification of unknown stabilisers in polyolefin samples.     

High-performance liquid chromatographic determination of alpha-tocopherol in macroalgae

A high-performance liquid chromatographic (HPLC) method for the microscale determination of alpha-tocopherol in macroalgae is reported. The method includes microscale saponification and extraction with n-hexane. The presence of alpha-tocopherol in macroalgae samples was confirmed by HPLC-MS. Alpha-tocopherol levels as determined in samples by HPLC with UV and fluorescence detection did not differ significantly; however, fluorescence detection has a higher sensitivity (detection limit 10.4 ng/ml, vs. 104 ng/ml with UV detection), as well as good precision (relative standard deviation 1.81%) and recovery (94.3%). Fluorescence detection is also faster. We used this method to determine the alpha-tocopherol contents of four commercial macroalgae products from northwest Spain as part of nutritional studies in dehydrated Himanthalia elongata and Laminaria ochroleuca, and also in canned Himanthalia elongata and Saccorhiza polychides.