Affinity chromatography with immunochemical detection applied to the analysis of human methionyl granulocyte colony stimulating factor in serum.

An on-line, automated, HPLC method was developed for the separation and detection of recombinant human methionyl granulocyte colony stimulating factor (GCSF) and GCSF modified with poly(ethylene glycol) (PEG-GCSF) in rat serum. The automated method consists of an initial immunoaffinity chromatography step, a microbore reverse phase separation, and postcolumn immunochemical detection. Calibration curves were constructed with a lower limit of 1.5 ng of GCSF (80 fmol) and 7.5 ng of PEG-GCSF in 120 microL of rat serum. In vivo serum samples from rats dosed with PEG-GCSF were also analyzed. The development of the method is discussed as well as its general application to the detection of metabolites of recombinant proteins in body fluids.