Ionization Characteristics of Glycan Homologues in Various Modes of Electrospray.

Fluorescence labeled glycan homologous mixtures were quantified using fluorescence and then used to evaluate ionization performances in electrospray ionization at micro, nano, and femto flow modes. nanoESI produced higher (2+ and 3+) charged ions adducted with sodium and calcium. In comparison, femtoESI was found to favor the generation of [M + H] ions against metal adducts, even with nonvolatile salts up to 1 mM for NaCl and 100 μM for CaCl.

Ultra-low current electrospray ionization of chloroform solution for the analysis of perfluorinated sulfonic acids.

Rationale: Femtoamp and picoamp electrospray ionization (ESI) characteristics of a nonpolar solvent were explored. The direct ESI mass spectrometry analysis of chloroform extract solution enabled rapid analysis of perfluorinated sulfonic acid analytes in drinking water.

Methods: Neat chloroform solvent and extracts were directly used in a typical wire-in ESI setup using micrometer emitter tips.