title: Separation of somatropin charge variants by multiple-injection CZE with Polybrene/chondroitin sulfate A double-coated capillaries.
abstract: The performance of dynamic double-coated fused-silica capillaries with Polybrene and chondroitin sulfate A has been compared with uncoated fused-silica capillaries for the determination of recombinant human growth factor (somatropin) charge variants. The separations were carried out under the same electrophoretic conditions as described in the European Pharmacopoeia, i.e. at pH 6.0 and 30°C. The coating significantly reduced the interactions between the proteins and the surface of the fused-silica capillary. The first five separations performed in a new bare fused-silica capillary were discarded because of very poor separation performance as a result of protein-surface interactions. There was an approximate twofold increase in the interday migration time precision (%RSD ≤ 6.5%) in the double-coated capillaries. The method was successfully transferred to a multiple CZE mode where two samples were analyzed in a single electrophoretic run. The average purity of somatropin certified reference standard was 98.0% (%RSD ≤ 0.3%) determined by using uncoated and coated capillaries.
authors.affiliation: Medical Products Agency, and Division of Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Biomedical Centre, Uppsala, Sweden. ahmad.amini@mpa.se
authors.forename: Ahmad
authors.initials: A
authors.lastname: Amini
mesh_terms: D002809:Chondroitin Sulfates / Q000737:chemistry; D019075:Electrophoresis, Capillary / Q000295:instrumentation / Q000379:methods*; D006583:Hexadimethrine Bromide / Q000737:chemistry; D019382:Human Growth Hormone / Q000737:chemistry / Q000302:isolation & purification*; D006801:Humans
chemical_list: D019382:Human Growth Hormone; D006583:Hexadimethrine Bromide; D002809:Chondroitin Sulfates
keywords: CZE; Double-coated capillaries; European Pharmacopoeia; Somatropin CRS; Somatropin charge variants