A new liquid chromatography/mass spectrometry interface: laser spray

Abstract

Explosive vaporization and mist formation occurs when an aqueous solution effusing from the tip of the stainless steel capillary (inner diameter: 0.1 mm) was irradiated from the opposite side of the capillary by a 10.6 μm infrared laser focused to ≈0.1 mm. Application of a high voltage (3–4 kV) to the stainless steel capillary produced strong signals of singly and multiply charged ions. The ion intensities were more than one order of magnitude stronger than those obtained by conventional electrospray or ion spray for the same aqueous samples. For some amino acid samples (e.g. leucine), cluster ions [H+ + (molecule)n], n=1–3, were observed by the present method, laser spray. This suggests that the sample solution was concentrated during the laser spray due to the rapid vaporization of solvent. This enrichment of the sample concentration may explain the high sensitivity of the present method. The degradation of thermally labile compounds was not observed. This method was found to be very versatile for the analysis of aqueous solutions of peptides, surface-active agents, metal ions, halide ions, etc., which are rather difficult to handle by the electrospray and ion spray techniques. © 1998 John Wiley & Sons, Ltd.