title: Determination of total protein in highly purified factor IX concentrates.
abstract: Protein determination by the methods of Kjeldahl, Biuret, Bradford and UV absorbance at 280 nm have been studied in regard to accuracy, precision and simplicity. A reference preparation of a highly purified factor IX concentrate, Nanotiv, reconstituted to 1/5 of ordinary volume was used in the study in order to make a comparison between the different procedures. The Kjeldahl method resulted in a protein concentration of 3.7 mg/ml, whereas the Biuret, Bradford (BSA) and UV absorbance at 280 nm resulted in protein concentrations of 3.6, 2.5 and 2.8 mg/ml, respectively. The corresponding values for specific activity were 136, 140, 200 and 179 IU/mg, respectively. These results demonstrate a great variation in the response obtained by different methods for determination of total protein.
authors.affiliation: Kabi Pharmacia AB, Plasma Products, Stockholm, Sweden.
authors.forename: A L
authors.initials: AL
authors.lastname: Löf
authors.forename: G
authors.initials: G
authors.lastname: Gustafsson
authors.forename: V
authors.initials: V
authors.lastname: Novak
authors.forename: L
authors.initials: L
authors.lastname: Engman
authors.forename: M
authors.initials: M
authors.lastname: Mikaelsson
mesh_terms: D001738:Biuret Reaction; D001798:Blood Proteins / Q000032:analysis*; D005164:Factor IX / Q000302:isolation & purification*; D006403:Hematologic Tests; D006801:Humans; D012015:Reference Standards; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001798:Blood Proteins; D005164:Factor IX