Mercury (Hg) is considered one of the most toxic elements to human health, due to its persistent
and bioaccumulative properties, and is present in all spheres of the environment. Artisanal smallscale gold mining (ASGM) activities in countries, such as in Kenya, use Hg as a method to
amalgamate gold from the geological matrix, with the potential to release Hg into the environment
and subsequent public health exposure. In order to measure Hg in environmental samples
improvements are required on existing recommended preservation methods for Hg in water
samples that may not be fit for purpose e.g. acidification or use of glass bottles are potentially
hazardous to operators in the field. Additionally, challenges are faced when samples are collected
in remote locations far from laboratories with sufficient analytical sensitivity for Hg, requiring a
preservation method that is safe to use during fieldwork, will preserve the analytical integrity of
the sample and provide sufficient stability over a time period to allow for return to an appropriate
laboratory. Therefore, a dithizone functionalised C18 solid phase extraction cartridge (SPE) was
developed to preserve Hg in water samples, with the aim of presenting minimal risk to the operator
when used in the field and to provide sufficient stability over a minimum of four weeks for
subsequent elution and measurement in a laboratory environment – in this case, by ICP-MS.
Performance characteristics were defined using a 0.8 µg L-1 Hg spike of a synthetic water matrix
typical from an ASGM outflow – 30ml of this spike was passed through the functionalised
cartridge and Hg eluted with 15ml of 2-mercaptoethanol (1% v/v with deionised water). The SPE
cartridge retained 100% of Hg in the spike solution and provided stability for Hg preservation
across a 57-day period, with recoveries of >75% Hg achieved following elution. Further work
shows promising recovery rates of up to 90% with adjusted dithizone functionalisation of the SPE,
without compromising retention of Hg on the SPE. Initial test data will be presented for ASGM
sites in Kakamega County, Kenya