Membrane-based detection of lead ions in seawater, urine and drinking straws through laser desorption/ionization

This paper reports the use of unmodified mixed cellulose ester membrane (MCEM) as a simple, novel andefficient substrate in matrix-free pulsed laser desorption/ ionization mass spectrometry (LDI-MS) for thedetection of lead ions (Pb2+) in water (tap water and coastal seawater) and biological (urine) samples anddrinking straws. The discovery of trace amounts of lead in the original MCEM prompted us to investigatethe special interactions between the MCEM and the Pb2+ ions. When using an MCEM, first to concentratePb(2+) ions and then as an efficient LDI substrate, our membrane-based LDI-MS approach exhibited highsensitivity [ limit of detection (LOD): 0.05 nM] and selectivity (tolerance at least 1000-fold relative toother metal ions) for the detection of Pb2+ ions in aqueous solutions. Based on the special ability of theMCEM, an easy method has been developed to detect Pb2+ ions in drinking straws, by simply rubbingthe straws with MCEM and then using LDI-MS. The ability of the MCEM to adsorb metal ions and itsinteresting surface functional properties should open up new opportunities for its application in LDI-MSfor the detection of other contaminants in environmental samples. (C) 2014 Elsevier B. V. All rights reserved.