A PRACTICAL COMPARISON WHEN DETERMINING MERCURY FOR CV-AFS AND ICP-MS
P S Analytical employs atomic fluorescence spectroscopy (AFS) which offers many advantages over other techniques for the determination of mercury and the hydride forming elements including better sensitivity, selectivity and linearity.
Of course ICP-MS is held up as the gold standard for many routine inorganic analyses and the technique is well established and accepted as such.
In the determination of Hg, however, there are some difficulties that are posed when using ICP-MS and the use of the stand-alone dedicated Hg analyser is often preferred.
Some of the issues when using ICP-MS for this analyte include;
Long wash out times as the Hg is difficult to remove from the sample introduction component. This slows the analysis considerably and adds cost in terms of argon consumption and other consumables
The addition of gold chloride can help here but, of course, adds to the complexity of the analysis as well as the cost
The fact that Hg have seven (stable) isotopes (all less than 30% abundant) immediately limits the sensitivity
The first ionization potential for Hg is high (10.44eV) and less than 5% of the atoms are ionized - again, limiting the sensitivity. The plasma needs to operate at the highest possible temperature to maximize efficiency
The ICP-MS can handle only a limited amount of total dissolved solids (TDS) from the sample matrix. This can be an issue with environmental, food and geological samples. High TDS levels can cause salts to deposit on the interface cones leading to loss of sensitivity and instability
The issue of high TDS also floods the plasma with free electrons further reducing the ionisation of the Hg atoms (which is already very low!) - again, sensitivity is affected
So given these above difficulties it is not surprising that many users prefer to use a stand-alone dedicated Hg analyser
The Millennium Merlin employees CV-AFS. The system does not suffer from long wash out times, can handle high TDS with ease and is more sensitive than the ICP-MS. These facts, together with its renowned robustness, ease of use and affordability make the Millennium Merlin the ideal choice for mercury determinations.
If you require any further information, please contact us via our Information Request Page.