Microdetermination of ergocalciferol (vitamin D2) in pharmaceutical preparations by differential spectroscopy using trifluoroacetic acid in the absence of vitamin A.
A differential spectroscopy method for the determination of microgram quantities of ergocalciferol, using trifluoroacetic acid and hydrogen peroxide, was applied to commercially available pharmaceutical preparations. Tablets were powdered and extracted with methanol after being made basic with diethylamine. The methanol was concentrated, chloroform was added, and the mixture was chromatographed on neutral alumina using chloroform as the eluent. Ergocalciferol was determined in an aliquot of the eluate by differential spectroscopy and was compared with a reference ergocalciferol standard treated similarly. The method applied to low potency formulations (2.5-6 mug/tablet) is simple and quantitative, needs less than 5 hr for completion, and has a precision of less than +/- 2%. A simple and accurate chromatographic method for the determination of ergocalciferol in stabilized powders and high potency tablets, which precludes the necessity of solvent-solvent extraction, was also developed. The results are comparable with those obtained by the rat bioassay and the USP XVIII chemical assay.
Studies of the stability and extractability of vitamin D.
Abstract Radioactively labelled vitamin D 3 -4-C 14 was used as a tracer to study the in vitro degradation of vitamin D. Effects were noted of various environmental conditions such as temperature, dispersion into water, exposure to air, oxygen, and ultraviolet light, with chromatography on alumina and Fluoropak 80 being employed to evaluate destruction. Procedures which avoided potentially damaging environments are described for saponifying tissues and extracting them of vitamin D and possible metabolites. They consist basically of refluxing with KOH in methanol, extraction by organic solvents in the presence of adequate concentrations of alcohol, and partition prior to chromatography or radioactivity assay.
Enhancement of surface properties on Low Density Polyethylene packaging films using various fluorination routes
Nowadays, packaging market deployment requires an important attention. Influence of treatment with molecular (F2) or atomic (Fradical dot) fluorine on properties of Low Density Polyethylene (LDPE) films was investigated. The films were treated using direct fluorination conditions with F2 or a specific reagent XeF2, which releases atomic fluorine Fradical dot. Changes of LDPE chemical composition were investigated by FTIR and solid state NMR. Surface morphology was studied by several microscopy techniques (SEM and AFM). Finally to further characterize film properties after treatments, surface energy measurements and electron paramagnetic resonance (EPR) analyses were also carried out. An upper fluorinated layer, which contains mainly high amount of single bondCF2single bond, was formed during the direct fluorination conditions (F2). For the process performed with XeF2, specific groups single bondCHFsingle bond were detected not only on the polymer surface but also in the bulk. The final CHF/CF2 ratio depended on the fluorination route. Treatment with Fradical dot (originated from XeF2 decomposition) resulted in single bondCHFsingle bond groups in bulk prevailing formation whereas F2 formed mainly single bondCF2single bond groups. Regardless to the reactive species, radicals (dangling bonds) appeared during the fluorination and reacted with oxygen during the exposition to air after the treatment. Such a process resulted in oxygenated polar groups formation and consequently in the surface energy increase.