Traceable Determination of Atmospheric Mercury Using Iodinated Activated Carbon Traps

Traceable determination of atmospheric mercury (Hg) represents a major analytical problem due to low environmental concentrations. Although Hg pre-concentration on activated carbon (AC) traps is a simple method for sample collection, Hg determination is difficult due to a complex matrix that cannot be easily digested using wet chemistry. Two approaches for Hg loading on iodinated AC, the purging of elemental mercury (Hg-0) and the spiking a solution of standard reference material (SRM), were used to test whether spiking SRM solution on AC can be used for the traceable determination of atmospheric mercury collected as Hg-0. Mercury on AC was determined using atomic absorption spectrometry after sample combustion. The detector's response for both loading methods was identical in a wide concentration range, indicating that the spiking of SRM on AC can, indeed, be used for the calibration of analytical systems used for the determination of atmospheric mercury. This was confirmed by the determination of Hg in a real atmospheric sample collected on an iodinated AC trap and using an SRM spiking calibration. Different ACs were compared regarding their ability to quantitatively capture Hg while having the lowest breakthrough. Use of a specific impregnating solution probably converted Hg on AC to Millon's iodide, as estimated from the fractionation thermogram.