Aerosol Interfacing Effects on Discrete Sample Introduction Coupled with Spectrometric Detection

Abstract

Aerosol techniques are commonly employed to interface discrete sampling techniques (flow injection analysis and liquid chromatography) with various detectors. The effects of these interfaces on discrete signals have not been described, nor has a rationale been established for presumed differences in band broadening due to aerosol-phase extra-column volume, compared to liquid-phase extra-column volume. In this report, the effects of laminar flow through several transport geometries on signal recovery and band broadening for both wet and desolvated aerosols are investigated. Data presented for the conditions studied indicate that signal losses with linear systems are primarily affected by gravitational settling. Increases in residence time lead to larger losses. Centrifugal effects, which lead to higher losses with coiled systems at high linear velocities, however, appear to have a stabilizing effect at lower velocities. Desolvation significantly reduces the level of gravitational or centrifugal losses via reduction in particle sizes. Band broadening results primarily from convection within laminar flow systems. This result was established on the basis of comparison of real signals with those generated from a convolution routine which mimics the effects of convective dispersion within laminar flows. The relatively high flow rates of aerosol transport systems result in short residence times and small effects of large transport volumes on dispersion. Sample losses also appear to offset band broadening to some extent by reducing peak tailing. Conditions providing efficient analyte transport and signal recovery, as well as low dispersion, can be established.