Polyaniline-coated nanoelectrospray emitters: performance characteristics in the negative ion mode

The increasing tendency to miniaturize analytical techniques has resulted in the widespread use of nanoelectrospray ionization mass spectrometry. A new polyaniline-coated nanoelectrospray emitter has shown increasing promise as a more durable and stable alternative to traditional metal-coated emitters. In this report, the utility of polyaniline-coated nanoelectrospray emitters in the negative ion mode is investigated. Here, oligonucleotides and peptides have been ionized in the negative mode using polyaniline-coated nanoelectrospray emitters. The emitters were found to be durable for at least an hour in the negative ion mode, during which time the signal was stable. The high amount of electrical discharge usually associated with negative ion mode nanoelectrospray was not problematic with the polyaniline-coated emitters. These characteristics make possible the reliable coupling of low-flow separations to negative ion nanoelectrospray without the worry of emitter failure during the course of the experiment.