title: Concentration determination of a recombinant vaccine antigen adsorbed onto an alum adjuvant by chemiluminescent nitrogen detection.
abstract: OBJECTIVE
  A chemiluminescent nitrogen detector (CLND) has been evaluated for determining the concentration of an aluminum-adsorbed recombinant vaccine antigen.
  
  
  METHODS
  Quantification of the antigen was based upon several nitrogen-containing compounds used to calibrate the CLND. All calibrants (6.75-400 microg/ml) generated linear standard curves, with slopes being directly proportional to the % nitrogen. The limit of quantification (LOQ) was determined to be 6.75 microg/ml based on the performance of the antigen standard curve, and the limit of detection (LOD) was defined by setting the CLND minimum peak area to 40,000 U. The CLND was capable of analyzing antigen-adjuvant suspensions (adsorbed + unbound antigen) without any sample pretreatment. To measure unbound antigen, the suspension was centrifuged and an aliquot of supernatant removed for analysis; the difference between these two measurements was the amount of adsorbed antigen.
  
  
  RESULTS
  The adjuvant exhibited no significant matrix effect. Samples were analyzed in triplicate with observed relative standard deviation values ranging from 0.065% to 10.0%. The most accurate concentrations of the antigen were recovered relative to the antigen itself and to glycine as standards.
  
  
  CONCLUSIONS
  This methodology provides a direct measurement of the concentration of a vaccine antigen adsorbed onto an aluminum adjuvant.
authors.affiliation: ID Biochemical Corporation of Northborough, Northborough, Massachusetts 01532, USA.
authors.forename: John V
authors.initials: JV
authors.lastname: Amari
authors.forename: Philip
authors.initials: P
authors.lastname: Levesque
authors.forename: Zhirui
authors.initials: Z
authors.lastname: Lian
authors.forename: Trish
authors.initials: T
authors.lastname: Lowden
authors.forename: Uditha
authors.initials: U
authors.lastname: deAlwis
mesh_terms: D000277:Adjuvants, Pharmaceutic / Q000032:analysis / Q000592:standards; D000327:Adsorption / Q000187:drug effects; D000534:Alum Compounds / Q000008:administration & dosage / Q000032:analysis* / Q000592:standards; D000941:Antigens / Q000008:administration & dosage / Q000032:analysis*; D002138:Calibration; D008163:Luminescent Measurements / Q000379:methods* / Q000592:standards; D009584:Nitrogen / Q000032:analysis* / Q000592:standards; D013056:Spectrophotometry, Ultraviolet / Q000592:standards; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000032:analysis* / Q000592:standards
chemical_list: D000277:Adjuvants, Pharmaceutic; D000534:Alum Compounds; D000941:Antigens; D014614:Vaccines, Synthetic; C041524:aluminum sulfate; D009584:Nitrogen