Organic ion imaging using tandem mass spectrometry.

A triple-quadrupole mass spectrometer has been interfaced with a wide-angle secondary ion microprobe. The combination permits acquisition of data necessary to determine the distribution of targeted organic analytes even in the presence of overwhelming isobaric interference. Micrographs generated from secondary ion intensity alone are compared to those generated using secondary ionization with tandem mass spectrometry (MS/MS), both for image reference and to show the improvement in image quality that can be attained when MS/MS is employed. Inhomogeneous mixtures of glycerol, KCl, and asparagine on 1-cm-diameter aluminum targets were used to demonstrate the instrument's selectivity. Secondary ions generated from samples of this system include isobaric 133Cs+ implanted from the primary ion beam, the 41K(+)-glycerol adduct, and protonated asparagine.