Another popular approach for cleaning samples prior to analyzing them by MALDI or electrospray
is using the ZipTipTM. ZipTipTM pipette tips are a 10 µl (P-10) pipette tip with a bed of resin fixed at
the end such that there is no dead volume. ZipTipTM Pipette Tips are useful for concentrating, desalting
and fractionating picomole amounts of peptide, protein or oligonucleotide samples prior to analysis. In
operation, ZipTips are affixed to a single or multi-channel pipette. Sample is aspirated and dispensed
through the tip to bind, wash and elute the analyte(s) of interest. The concentrated, purified sample is
precisely eluted in 1–4 µl of eluant.