A simple in-house dry ashing chamber for the rapid determination of total mercury in organic-rich solid materials by oxidative pyrolysis followed by CVAAS and FI-ICPMS detection

Abstract

A simple in-house pyrolysis chamber made of quartz material is described for the determination of total mercury content in a wide variety of organic-rich solid materials (plant, fish tissues and polymer based) by oxidative pyrolysis and cold vapour atomic absorption spectrometry (CVAAS). Oxidative pyrolysis was carried out by means of a Bunsen burner in the presence of an oxygen stream. Mercury liberated from the sample was collected in 0.1% KMnO₄ trapping solution. Determination of mercury was achieved by CVAAS. Under optimal conditions, the limit of detection (LOD), calculated as the concentration of mercury yielding a signal equivalent to three times of the standard deviation of the blank value (3σ), obtained for CVAAS in conjunction with the oxidative pyrolysis method was found to be 0.08 ng g⁻¹. Flow injection inductively coupled plasma mass spectrometry (FI-ICPMS) was used to validate the developed method. The results obtained for several reference materials, such as mussel tissue (CE-278), tuna fish (CE-463), tuna fish (464), polyethylene (EC-681), plankton (CRM-414), lichen (CRM-482) and human hair (CRM-397), by the developed method agreed well with the certified values. These studies clearly demonstrate the capabilities of the pyrolysis set-up that can potentially be used for the rapid determination of total mercury in a wide variety of organic-rich matrices.