Versatile computer controlled interface system for directly coupled high-performance liquid chromatography-flame atomic absorption spectrometry

Abstract

A computer controlled interface system is described for directly coupled high-performance liquid chromatography-flame atomic absorption spectrometry (HPLC-FAAS). The eluent from the HPLC is collected on a series of 20 rotating platinum spirals, desolvated by an electrically heated furnace and finally transported into an atomising air-acetylene flame. The spirals are rotated by a stepper motor (1.8° step angle) which is controlled by a microcomputer. The transient atomic absorption signal for each spiral is fed to the analogue to digital converter of the computer, via a simple interface, for data display and manipulation. The sensitivity of the interface was found to be about two orders of magnitude better than for conventional FAAS using nebulisation, detection limits for Cd, Hg, Pb and Zn were in the low nanogram to picogram range. The factors affecting the sensitivity and precision are reported. The interface was evaluated for the speciation of mercury compounds. Detection limits for Hg²⁺, CH₃Hg⁺ and C₆H₅Hg⁺ were 3.5, 1.9 and 2.5 ng (as Hg), respectively. At the 40-ng level the mean relative standard deviation was 7%.