An electropneumatic-heated nebulizer for enhancing spray ionization in PhotoSpray atmospheric pressure photoionization sources for liquid chromatography/mass spectrometry

摘要

We introduce a novel electropneumatic-heated nebulizer (EPn-HN), incorporating an electrifiedinternal pneumatic nebulizer, to enhance the yield of sprayed ions from PhotoSpray~(TM)atmosphericpressure photoionization (APPI) sources for liquid chromatography/mass spectrometry (LC/MS).Spray ionization from the pneumatic-heated nebulizers used in APPI sources provides a supple-mental, complementary ionization method to be used for involatile and thermally labile compounds,otherwise intractable to APPI. Details of the construction and operation of the EPn-HN device areprovided. The performance of the EPn-HN is demonstrated using two model compounds: substanceP, a peptide used as a standard in studies of ion fragmentation mechanisms, and aztreonam, athermally labile antibiotic. At the optimum voltage for spray ionization, improvements in sensitivityof two orders of magnitude are obtained relative to when the sprayer is grounded, the conventionalcase. Since both substance P and aztreonam cannot be detected using the APPI method alone, theresults demonstrate how spray ionization from the EPn-HN may be used to extend the range ofcompounds amenable to PhotoSpray sources.