title: On-demand ambient ionization of picoliter samples using charge pulses.
abstract: Relay electrospray ionization (rESI) from a capillary containing a sample solution (or from an array of such capillaries) is triggered by charge deposition onto the capillary. Suitable sources of primary ions, besides electrosprays, are plasma ion and piezoelectric discharge plasma sources. With no requirement for physical contact, high-throughput sample screening is enabled by rapidly addressing individual secondary (sample) capillaries. Sub-pL sample volumes can be loaded and sprayed. Polar analytes, including neurotransmitters, phosphopeptides, oligonucleotides, illicit drugs, and pharmaceutical compounds are successfully ionized by rESI with concentration sensitivities (0.1 ppb for acetylcholine) which are similar to nanoESI but absolute sensitivities are orders of magnitude better. Nonpolar analytes (steroids, alkynes) are ionized by rESI using an open-tube secondary capillary and injecting electrolytically generated metal cations from the primary electrospray.
authors.affiliation: Department of Chemistry and Center for Advanced Analytical Instrumentation Development, Purdue University, 560 Oval Drive, West Lafayette, IN 47907 (USA). li273@purdue.edu.
authors.forename: Anyin
authors.initials: A
authors.lastname: Li
authors.affiliation: Department of Chemistry and Center for Advanced Analytical Instrumentation Development, Purdue University, 560 Oval Drive, West Lafayette, IN 47907 (USA).
authors.forename: Adam
authors.initials: A
authors.lastname: Hollerbach
authors.affiliation: Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, PA 19104 (USA).
authors.forename: Qingjie
authors.initials: Q
authors.lastname: Luo
authors.affiliation: Department of Chemistry and Center for Advanced Analytical Instrumentation Development, Purdue University, 560 Oval Drive, West Lafayette, IN 47907 (USA). cooks@purdue.edu.
authors.forename: R Graham
authors.initials: RG
authors.lastname: Cooks
keywords: electrohydrodynamics; electrospray ionization; mass spectrometry; microaspiration; piezoelectric