|Abstract Title:||The comparison of Unispray and Electrospray for the ionization of neuropeptides|
|Session Choice:||Interfacing and Ionisation|
|Presenter Name:||Mr Yannick Van Wanseele|
|Co-authors:||Dr Marijn Van Hulle|
Dr Laurence Van Oudenhove
Prof Ilse Smolders
Prof Ann Van Eeckhaut
|Company/Organisation:||Vrije Universiteit Brussel|
Abstract Information :
In the world of bioanalytical chemistry, electrospray ionization (ESI) is one of the most prominent ionization techniques. Its soft ionization mechanism and compatibility with liquid chromatography are the main incentives leading its popularity. However, the technique is prone to low ionization efficiency and low ion transmission towards the mass spectrometer vacuum chambers. To tackle these drawbacks, liquid chromatography infusion flow rates were reduced over the years to nanoL/min, creating smaller droplets and as such aiding desolvation. In parallel, variations in source design were explored for increasing the ion transmission through the sample cone.
More recently, a new ionization source was developed and commercialized as 'Unispray'. In this atmospheric pressure setup, a grounded solvent flow is nebulized onto a high voltage charged rod. In addition to ionizing the compounds of interest, Coandă and vortex effects aid droplet break-up and desolvation. In the last two years, differences in ionization between ESI and Unispray were already thoroughly investigated by Lubin et al for the analysis of small molecules . In our experiments we compared the ionization of seven neuropeptides, varying between 6 and 36 amino acids, via Unispray and ESI at different impactor and capillary voltages respectively. All peptides were infused in acetonitrile/water (30:70 V/V) containing 0.1% formic acid at 100 µL/min. We also examined the effect of different additives such as m-nitrobenzyl alcohol, dimethylsulfoxide and sulfolane on the peptide charge state distribution and signal intensity.