Multi-residue liquid chromatography/tandem mass spectrometric analysis of beta-agonists in urine using molecular imprinted polymers

Ion suppression, a matrix effect that affects quantitative mass spectrometry, is one of the main problems encountered in liquid chromatography/tandem mass spectrometry. Two different clean‐up steps for the multi‐residue analysis of beta‐agonists in urine were evaluated with respect to minimisation of ion suppression, namely, a mixed‐phase solid phase extraction (SPE) column, i.e., clean screen Dau (CSD), and a molecular imprinted polymer (MIP) SPE column. Ion suppression experiments revealed that CSD sample clean‐up can lead to false negative results for some beta‐agonists, and that clean‐up using MIP columns is more selective for beta‐agonists than the use of CSD columns. Copyright © 2005 John Wiley & Sons, Ltd.