Determination of Mercury (Hg) in Water by Hand-Held, Portable Cold Vapor Atomic Fluorescence Spectrometry

With the presence of running water in our everyday domestic lives it may be easy for people to believe that all water we encounter is abundant and usable. The fact is, only 2.5% of the Earth’s water is freshwater, and only a small percentage of that is both usable and easily accessible. Because of the precious and fixed reserves of water at our disposal, it is vital to protect our water resources from contaminants that harm all forms of life if consumed. One of the hazardous pollutants that will render water unusable is mercury. This poisonous element can be readily dispersed in water and can accumulate in watersheds, where it is then absorbed by plants and consumed by animals. Because of bio-accumulation of mercury in the food chain, and its toxicity in minute concentrations, the European Parliament has classified mercury as a priority hazardous substance in The Water Framework Directive, establishing a structure for Community action in the field of water policy.

High doses of mercury can be fatal to humans, but even relatively low doses can have serious impacts on the body’s systems. Mercury has been linked with possible effects on the cardiovascular, immune and reproductive systems. Mercury in the environment can change into methyl mercury, the most toxic form. Methyl mercury can cross the placenta in pregnant women and can affect mental development in unborn babies.

Atomic absorption spectroscopy (AAS), along with gold film sensing, has long been the leading method for mercury detection down to sub microgram quantities. However, AA presents problems in the presence of hydrocarbons since these molecules absorb at the same wavelength as Hg. Atomic fluorescence (AFS) was first recognised as a useful analytical method in 1964 but has not been widely used until recently. For mercury detection, this method proves more useful than atomic absorption since it reduces the possibility of signaling from other chemical compounds. This is due to the fact that elemental mercury fluoresces at a different wavelength to other compounds.

The Jerome® J505 is the most advanced handheld mercury analyser available and the only handheld mercury analyser on the market that uses AFS. The J505 is lighter, more selective, and more robust than analysers based on AAS, which are traditionally large, stationary instruments designed for laboratory conditions. The J505 can effectively measure elemental mercury in water by analysing the headspace above a contaminated water sample without using a gold film trap. The portability allows for use outside of the lab, providing results as samples are drawn. Initial tests have shown that the instrument effectively detects concentrations down to 10ng/m3. Further evaluation is still to be done to determine the lower detection limit of the instrument, as well as analysis optimisation that would reduce testing and throughput time.

The highly efficient optical cell requires less flow to purge the system, allowing the J505 to run at low flow rates, therefore significantly reducing the sample dilution requirements

associated with rival instruments. A low flow rate is vital for making accurate readings at low very low mercury concentrations.

For details of the scientific procedure please refer to the white paper on our website

The J505 emanates from the same stable as the industry proven Jerome J405 Portable Gold Film Mercury Analyser. The J405 has already become the Hg vapour analyser of choice for the majority of the major North Sea oil and gas operators for hazard assessment and for mercury spill detection and clean-up analysis.