AFFINITY MEMBRANE INTRODUCTION MASS-SPECTROMETRY

A new technique, affinity membrane introduction mass spectrometry, is described. In this method, a chemically modified membrane is used to s electively adsorb analytes bearing a particular functional group and c oncentrate them from solution. Release of the bound analyte results in its transfer across the membrane and allows it to be monitored mass s pectrometrically, using, in the present case, a benchtop ion trap inst rument. Alkylamine-modified cellulose membranes are used to bind subst ituted benzaldehydes through imine formation at high pH. Release of th e bound aldehyde is achieved by acid hydrolysis of the surface-bound i mine. Benzaldehyde is detected with excellent specificity at 10 ppm in a complex mixture using this method. Using the enrichment capability of the membrane, a full mass spectrum of benzaldehyde can be measured at a concentration of 10 ppb. The behavior of a variety of other aldeh ydes is also discussed to illustrate the capabilities of the method.