Total reflection X-ray fluorescence mercury analysis after immobilization on quartz surfaces

Quartz reflectors are a common substrate for total reflection X-ray fluorescence (TXRF) analysis. Especially low masses of trace elements can be determined on these surfaces. In the present work, various complexing reagents were immobilized on the surface of quartz reflectors. The reflectors were immersed in mercury solutions and selective mercury collection took place. The effect of immersion time was examined and a few minutes were found adequate. The reflectors were analysed for mercury by TXRF. Different complexing reagents showed different collection capabilities; 4-(2-pyridazo-resorcinol) gave the best among them. The effect of various experimental parameters was examined like pH, interferences from other ions, etc. Mercury speciation was successfully tested by comparing inorganic mercury results with the methyl mercury ones. A very good selectivity for inorganic mercury was found. It was achieved very good linearity in the 1-500 ng mL⁻¹ mercury concentration range and the minimum detection limit was equal to 2.5 ng mL⁻¹.