Portable and miniature mercury analyzer using direct sampling inbuilt-metal ceramic electrothermal vaporization

In this work, a small-size inbuilt-metal ceramic heater (IMCH) was for the first time utilized as a solid sampling electrothermal vaporizer (ETV), and then a novel direct sampling mercury analyzer coupled with a miniature atomic absorption spectrometer was thereby fabricated for sensitive determination of mercury in soil. The mercury analyzer is mainly composed of an IMCH-ETV, a catalytic pyrolysis furnace (CPF) using Al₂O₃ particles as a new filler, an atomic absorption spectrometer (AAS) and a miniature air pump for carrier gas; herein, the mostly used gold amalgamation was canceled. The IMCH with 30 W heating fulfills the 100% vaporization of mercury from up to 80 mg soil samples using 0.1 L min^-1 air carrier. Under the optimized conditions, the method detection limit (LOD) was 0.4 ng g^-1 for a 50 mg sample and the RSD of 11 repeated measurements of GSS-3a soil certified reference material (CRM) was 4%. Furthermore, the measured Hg values in various soil CRMs and real soil samples were within their certified values and consistent with that using the Chinese standard method (solid sampling catalytic pyrolysis AAS with gold amalgamation); and the recoveries were 85-113%, which proved favorable analytical accuracy and precision. This fabricated instrumentation only occupies 5 kg and 200 W power consumption vs. more than 25 kg and 1000 W for the traditional Hg analyzer. Therefore, the proposed IMCH-ETV-AAS method is very suitable for portable and rapid detection of mercury in soil.