The invention provides extraction columns for the purification of an
analyte (e.g., a biological macromolecule, such as a peptide, protein or
nucleic acid) from a sample solution, as well as methods for making and
using such columns. The invention is characterized by the use of low dead
volume columns, which is achieved in part by the use of low pore volume
frits (e.g., membrane screens) to contain a bed of extraction media in
the column. Low dead volume facilitates the elution of the captured
analyte into a very small volume of desorption solution, allowing for the
preparation of low volume samples containing relatively high
concentrations of analyte.