Technical Report: Development of a Piezoelectric Inkjet Dopant Delivery Device for an Atmospheric Pressure Photoionization Source with Liquid Chromatography/Mass Spectrometry

This paper describes a simple, robust and integrated piezoelectric actuated printhead as a dopant delivery system for atmospheric pressure photoionization with liquid chromatography/mass spectrometry. The newly designed dopant delivery system avoids problems associated with traditional liquid delivery systems such as solvent immiscibility, backpressure and increased post-column dead volume issues. The performance of the new device was tested and evaluated using chlorobenzene as a dopant with a test mixture consisting of 18 different polycyclic aromatic hydrocarbons (PAHs). The results show that the new system works robustly at low dopant consumption level (1.6 uL min⁻¹), consuming only approximately 5% of the amount used by conventional sources. The low dopant consumption has resulted in up to a 20-fold reduction in signal intensity of tested PAH molecules, but has led to less presence of background cluster ions and dopant trace contaminant background ions in the source area. Consequently, all tested PAHs were detected with excellent signal-to-noise ratio with at least two- to ten-fold improvements in the limit of detection and quantification compared to those obtained with traditional dopant assistance using a post-column addition method.