title: Development of a routine analysis method for liposome encapsulated recombinant interleukin-2.
abstract: This paper describes the development of an isocratic reversed-phase high-performance liquid chromatographic method for the routine analysis of recombinant interleukin-2 (rIL-2) in liposome samples. The chromatographic system employed a C4 column maintained at 30 degrees C eluted with 52.5% (w/w) acetonitrile in water, containing 100 mM NaClO4 and 10 mM HClO4. To remove phospholipid interference the chromatographic method was combined with a lipid-extraction procedure. No significant loss of rIL-2 was noted upon inclusion of this extraction step. The protein eluted from the column with a capacity factor (k') of 5.8. The method was validated for robustness, linearity, precision and reproducibility. It was shown that the method was linear over a sample concentration range of 1-100 microg/ml. Upon assessment of the intra-day and inter-day precision, the relative standard deviations (RSD) were within the range of the methodical error (approximately 5%), except at the lower concentration of 10 microg/ml, where the intra-day RSD was relatively high (17.8%). The recovery of rIL-2 upon liposome preparation and subsequent analysis of the samples was in the range 94+/-9%. The results indicate that the method is suitable for routine quantitation of rIL-2 in liposomal samples.
authors.affiliation: Department of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands.
authors.forename: F J
authors.initials: FJ
authors.lastname: Koppenhagen
authors.forename: G
authors.initials: G
authors.lastname: Storm
authors.forename: W J
authors.initials: WJ
authors.lastname: Underberg
mesh_terms: D000097:Acetonitriles; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D007376:Interleukin-2 / Q000032:analysis*; D008081:Liposomes / Q000737:chemistry*; D008715:Methionine / Q000737:chemistry; D010084:Oxidation-Reduction; D011994:Recombinant Proteins / Q000032:analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013696:Temperature
chemical_list: D000097:Acetonitriles; D007376:Interleukin-2; D008081:Liposomes; D011994:Recombinant Proteins; D008715:Methionine; C032159:acetonitrile