Merged electrospray ionization mass spectrometry

Ambient ionization allows the analysis of materials in their native environment without sample preparation by creating ions outside the mass spectrometer. The goal of this research was to develop new ambient ionization techniques for application to solids, liquids and particles under ambient conditions. Samples to be analyzed were directly merged with an electrospray of droplets, and then ionized and detected by a mass spectrometer. An ion trap mass spectrometer was modified with a nanoelectrospray source and configured for three experiments: merged electrospray ionization of dry particles, merged electrospray ionization of combustion products, and infrared laser desorption/ablation using electrospray for post-ionization. In the first set of experiments, materials in powdered samples were ionized directly by interaction with an electrospray of charged solvent droplets. The powdered samples were dispersed as dry particles with an aerosol generator. The study included amino acids and antibiotics, as well as food and pharmaceutical samples. Singly-charged peaks, corresponding to major components in the powdered samples, were detected using this method. The second set of experiments directly analyzed combustion products generated from the burning of cigarettes, incense, candles, and organic fuels by merging these with electrospray for ionization. This approach allowed the detection of major components in the smoke of cigarettes, incense, and candles, and polycyclic aromatic hydrocarbons generated from combustion of organic fuels. In the third set of experiments, an infrared laser was used to desorb and ablate samples placed on a stainless steel sample target, and electropray droplets interacted with the ablated materials to generate ions. Protein standards, biological fluids, and pharmaceutical products were analyzed using this technique. The spectra of the materials analyzed were similar to conventional electrospray.