Closed-system trapping method for the direct determination of transport efficiency in electrothermal vaporization sample introduction

A novel closed-system for the direct determination of analyte transport efficiency in electrothermal vaporization (ETV) sample introduction is described. A commercially available gas-sampling bag filled with 100 ml of 10% HNO3 was connected to the exhaust of an ETV system and used to collect and seal the product of an electrothermal vaporization event. The bag was then manually agitated, and its liquid contents decanted and analyzed by solution nebulization ICP-MS. Analyte transport efficiency values were found to be in statistical agreement with those determined by a reference method on the same ETV system for a variety of volatile (As, Cd, Mn, Pb), involatile (Cu, Ni) and refractory carbide forming (V) elements. This simple experimental setup captures all of the analyte in a single solution, with the closed-system element of its design ensuring that this is done quantitatively. Absolute detection limits for most elements were of the order of 0.1-10 ng absolute for the technique, making it well suited for analyte masses typically vaporized in ETV-ICP-OES. The relative merits of using this type of setup for the determination of analyte transport efficiency in ETV sample introduction, along with experimental considerations, are described.