Extraction of thromboxane B2 from urine using an immobilized antibody column for subsequent analysis by gas chromatography-mass spectrometry.

This paper describes an antibody affinity (immunoaffinity) column which, in one step, extracts and sufficiently purifies urinary thromboxane B2 (TXB2) for quantitative analysis by high resolution gas chromatography-negative ion chemical ionization-selected ion monitoring-mass spectrometry (HRGC-NICI-SIM-MS). Polyclonal TXB2 antibody from rabbit was partially purified using immobilized Staphylococcus aureus Protein A. The purified IgG fraction was then immobilized using an N-hydroxysuccimidyl silica gel. The resulting matrix bound 570 ng TXB2 per ml of gel. TXB2 was quantitatively eluted with acetonitrile-water (19:1). Columns constructed from the gel could be used repeatedly since binding capacity was reconstituted using 0.01 M phosphate buffer (pH 7.4) with no apparent loss of activity. Using these columns, urinary TXB2 was sufficiently purified in one step such that in subsequent analysis by HRGC-NICI-SIM-MS interference free chromatograms were observed.