A new on-line version of the gold amalgamation trap for interference-free determination of Hg0 in crude oil and related products by Zeeman CV-AAS

Abstract

A new on-line version of the gold amalgamation trap was proposed for the determination of Hg⁰ in crude oil and related products prior to its detection by atomic absorption spectrometry. On-line analyses were carried out by a homemade gold amalgamation trap (GAT), heated at 120 °C during the Hg⁰ amalgamation, coupled to a commercial mercury analyzer, containing a spectral corrector based on the Zeeman effect. The heating avoided the collection of many volatile hydrocarbons onto the trap, and the Zeeman-effect corrector avoided the interferences caused by part of the organic vapors, which were collected onto the trap during the Hg⁰ amalgamation. Experimental parameters such as carrier gas flow, Hg⁰ release temperature and Hg⁰ amalgamation time were investigated. LOD and LOQ values of 0.06 and 0.21 μg L⁻¹ Hg⁰ were obtained, respectively. Precision was always better than 10%. Quantitative Hg⁰ recoveries (85–116%) were obtained for the spiked certified reference materials and spiked crude oil, diesel and gas condensate samples.