Heat-assisted argon electrospray interface for low-flow rate liquid sample introduction in plasma spectrometry.

A heated (approximately 90 degrees C) laminar flow interface has been designed to assist in the development of an argon electrospray sample introduction system for low-flow rate applications using inductively coupled plasma (ICP) spectrometry. Previously, the stability and robustness of the ICP were compromised by the entrainment of air, N2, or gas mixtures (e.g., Ar-N2) from the electrospray source. Also, more concentrated organic solvents (e.g., 50% (v/v) methanol-water), typically introduced by electrospray, could generate carbon deposits that obstruct the entrance lens to an ICP optical emission spectrometer (ICP-OES) or the sampler/skimmer cone interface in an ICP mass spectrometer (ICP-MS), decreasing analyte sensitivity. With the new interface design, a stable spray of 5% (v/v) methanol-water in a pure argon environment is achieved, eliminating the aforementioned problems. The turbulence and the consequent droplet loss caused by high gas velocity around the electrospray capillary are mitigated by the use of a laminar-flow gas with the aid of a flow diffuser. The argon electrospray interface is successfully installed on an ICP-OES and an ICP-MS for the first time.