Liquid nebulization in ion sources for mass spectrometry

Mass spectrometry is a powerful analytical technique used to identify and quantify compounds by means of the mass-to-charge ratio of ions produced from a sample. Nowadays, mass spectrometry is often combined with liquid chromatography, which separates analytes based on the interactions they have with the column and the mobile phase. The analytes are mostly ionized in the liquid phase using an electrospray that employs electricity to disperse a liquid into a fine aerosol. Although the electrospray ionization is an almost versatile technique, it shows a limited performance for some analytes. Low polarity analytes are more efficiently ionized using gas-phase processes initiated by electrons or photons. These ionizations require efficient nebulization of dissolved samples at high temperatures, often assisted by the gas flow. The mist generated in the nebulizer is converted into a gas stream that later interacts with electrons or photons. Heated nebulizers are key parts of ion sources for atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI). Unfortunately, commercial sources for APCI and APPI are incompatible with low flow rates used in modern liquid chromatography, which significantly limits their applicability in analytical chemistry.

The aim of this project is to design and fabricate a nebulizer (a spray nozzle) for an ion source operating at 1-10 microliters per minute (flow rates of liquid). The device must ensure efficient nebulization of the liquid and efficient focusing of a gas stream into the ionization region of the ion source (APCI or APPI). The Ph.D. student should have manual skills and technical training ideally in the field of fluid mechanics. The project will be implemented in cooperation with the Development Center of the IOCB (engineering assistance, workshop production) and is supported by a grant project of the Czech Science Foundation.

Field of study: Analytical chemistry