Biomedical subjects

D R Jenke

Publications and source records attributed to D R Jenke.

23 records · Page 2Linked to original sources

PubMed1987

Application of fast LC to pharmaceutical analysis: dopamine.HCl.

A reversed-phase HPLC method for the determination of the dopamine hydrochloride content of pharmaceutical intravenous solutions is developed using short (3-cm) columns packed with 3-micron particles. Total analysis time for the stability indicating assay, which is capable of separating the analyte from all its common degradates and formulation matrix components, is 2 min. The assay is equivalent in performance (accuracy, precision, separation behavior, ruggedness) to a standard method recommended by the United States Pharmacopeia (USP). Common components of conventional HPLC systems are evaluated with respect to their utility for this application of fast LC.

Chromatography, Liquid↗

PubMed1987

Determination of oxalate in pharmaceutical matrices by indirect photometric chromatography.

An indirect photometric ion chromatography method is developed for the quantitation of oxalate in typical pharmaceutical matrices. The column/mobile phase conditions used represent a trade off between resolving power and sensitivity and results in an assay with a total analysis time of less than 9 minutes. Method response is linear between concentrations of 10 to 80 ppm oxalate. The limit of quantitation is roughly 5 ppm. Precision in the range of 30 to 80 ppm is better than 1.0% RSD of replicate injections, and the accuracy in a variety of matrices is 100 +/- 2%. The method is quite rugged and meets rigorous suitability requirements even after 500 injections. Although the assay can be used to quantitate citrate as well, the retention time is relatively long (20 minutes) and sensitivity is limited due to the broadness of the peak.

Chromatography↗

PubMed1985

Application of indirect photometric chromatography to pharmaceutical analysis.

Indirect photometric chromatography, which couples analyte separation by ion exchange with indirect photometric detection, is applied to the analysis of complex solutions encountered in the pharmaceutical industry. Applications of primary interest include simultaneous acetate, lactate, chloride, or phosphate determinations, a bisulfite/sulfate assay, and quantitation of trace levels of chloride in deionized water. Three commercially available ion chromatography columns are studied for their suitability in these applications. Due primarily to (A) the acid-base chemistry of the phosphate and bisulfite ions, (B) the need to stabilize the readily oxidized bisulfite, and (C) resin stability at high pH, the column packed with a polymer-based resin is capable of producing analytically superior separations of Cl-, HPO4-2, and matrix components and of SO3-2/SO4-2 in the samples of interest. Under rigid relative concentration conditions, the columns packed with a silica backbone resin are capable of separating acetate, lactate, Cl-, and H2PO4- with baseline resolution and are effective for determining Cl- levels at concentrations of less than one part-per-million.

Acetates↗

PubMedDate not supplied

Additive model for the evaluation of interactions between aqueous solutes and multi-component container materials.

The interaction between aqueous model solutes and various current or potential parenteral solution container materials was studied. Materials examined included composite polymers (plasticized PVC and co-extruded composites) and their individual components. For each material studied (component and composite), the equilibrium interaction constant (Eb), which describes the distribution of a solute between a container and its contained solution, can be related to the solute's octanol-water (Po-w) and hexane-water (Ph-w) partition coefficients via a bimodal Collander-type expression: log Eb = a log Po-w + b log Ph-w + c Additionally, the interaction of the composites was found to be equivalent to the weighted average of the interaction properties of its individual components. That is, Eb,composite = sigma Wi x Eb,i where i represents an individual component of the composite and Wi represents the weight fraction of that component in the composite. The impact of the interaction properties of the components on the behavior of the composites is discussed; thus, for example, the interaction properties exhibited by plasticized PVC is dominated by the behavior of the plasticizer since unplasticized PVC itself exhibits only minimal interaction with aqueous solutes.

Composite Resins↗

PubMedDate not supplied

Accumulation model for solutes leaching from polymeric containers.

An accumulation model for predicting the equilibrium solution concentration of leachables migrating from polymeric containers has been applied to the leaching of several solutes from a blend of a styrene-butadiene-styrene block co-polymer and polypropylene. The model considers three accumulation-limiting mechanisms: total available pool, solute solubility and solute partitioning. Equations relating a solute's solvent-water partition coefficients (Po/w and Ph/w) and its polymer partitioning properties have been developed. With these equations, one can predict leachable accumulation from the container weight, solution volume and the solute's partition coefficients. The maximal accumulation of the leachable in solution will be the lowest value predicted via the three accumulation-limiting mechanisms.

Caproates↗