Development of a microcolumn one-site immunometric assay for a protein biomarker: Analysis of alpha 1 -acid glycoprotein.

•A one-site immunometric assay using affinity microcolumns was developed and tested.•Alpha1-acid glycoprotein (AGP) was used a model protein biomarker for this work.•Several theoretical and practical factors were considered in creating this assay.•The final method required only 1 µL serum and had a detection limit of 0.63 nM AGP.•The same approach can be easily modified for use with for other protein biomarkers.