Multisite evaluation of a monoclonal IMMULITE erythropoietin immunoassay.

Background: Erythropoietin (EPO) measurements are useful in diagnosing anemias and polycythemias. We conducted a multisite evaluation of a monoclonal IMMULITE® EPO immunoassay.(1) DESIGN AND METHODS: The IMMULITE EPO assay is a solid-phase enzyme-labeled chemiluminescent immunometric assay.

A weak cation-exchange monolith as stationary phase for the separation of peptide diastereomers by CEC.

A CEC weak cation-exchange monolith has been prepared by in situ polymerization of acrylamide, methylenebisacrylamide and 4-acrylamidobutyric acid in a decanol-dimethylsulfoxide mixture as porogen. The columns were evaluated by SEM and characterized with regard to the separation of diastereomers and α/β-isomers of aspartyl peptides. Column preparation was reproducible as evidenced by comparison of the analyte retention times of several columns prepared simultaneously.

Capillary electrophoresis-based sirtuin assay using non-peptide substrates.

Sirtuins are NAD(+)-dependent class III histone deacetylases, which catalyze the deacetylation of acetyl-lysine residues of histones and other protein substrates yielding the deacetylated protein, nicotinamide and 2'-O-acetyl-ADP-ribose. Two lysine amide derivatives containing dansyl (Dns) or 7-dimethylaminocoumarin (DMAC) residues, i.e.

Separation of peptide diastereomers using CEC and a hydrophobic monolithic column.

A neutral hydrophobic monolith prepared by radical in situ copolymerization of lauryl methacrylate and ethylene dimethacylate has been evaluated for the CEC separation of diastereomers of small peptides using acidic mobile phases containing ACN as organic modifier. Using an acidic mobile phase, the peptides migrated due to their own electrophoretic mobility. Hydrophobic interactions with the stationary phase contributed to the separation.

Application of phase optimized liquid chromatography to oligopeptide separations.

Stationary phase optimized liquid chromatography (POPLC) has been applied to the separation of oligopeptides. The retention factors and theoretical plate numbers of 13 peptides were determined on five different stationary phases. Based on these values, an optimal stationary phase composition of 250mm total length consisting of 3 segments of 20mm octadecyl silica, 10mm phenyl silica and 220mm embedded polar octadecyl silica was calculated by the optimizer software.