Quicksilver Scientific technology is unique amongst analytical laboratories. Other companies rely on EPA draft methods 1630, 1631, and 247.5 to analyze mercury. However, these methods are labor-intensive, with opportunities for interference, which may explain why the EPA hasn’t adopted any of these drafts as a full method.

Here are some of the key differences between the Quicksilver method and EPA draft methods.

Highly Accurate VS. Acceptably Accurate

EPA methods are complicated and labor-intensive, increasing the chance for error. As such, the quality control acceptance criteria fall within a wide range.

The Quicksilver method allows for tight quality control parameters. Compare the EPA quality control acceptance criteria to Quicksilver’s.

Affordable with More Data VS. Expensive with Less Data

EPA draft method 1630 cannot produce data for species of mercury. To get methylmercury numbers, 1630 must be combined with 1631. However, these two independent methods are labor-intensive and slow, making them expensive as well.

The Quicksilver method analyzes methylmercury, inorganic mercury, and total mercury in one simultaneous procedure. (See how Quicksilver speciation analysis provides total mercury data as well.) The Quicksilver method is also automated and scaleable to handle very large sample batches. Per sample, the Quicksilver method is much more affordable and much more capable of handling large sample throughput.

Flexible Sample Sizes VS. Large Sample Sizes

EPA draft method 1630 is not suitable for small sample sizes, as the method cannot concentrate the mercury prior to analysis.

The Quicksilver method, however, binds mercury species to the analytical system and controls the release of mercury into the system. This gives Quicksilver Scientific the ability to analyze smaller samples and mercury concentrations than other companies.

One Analytical Procedure VS. Several Analytical Procedures

EPA draft methods do not offer one process for analyzing methylmercury (MeHg) and inorganic mercury (Hg^II). EPA draft method 1630 and draft method 247.5 only analyze total mercury (HgT). EPA draft method 1631 only analyzes MeHg.

The Quicksilver method determines MeHg, Hg^II, and HgT in one simple analysis. This makes the Quicksilver method efficient, allowing us to reduce our price and turn-around time.

Strong Extraction Chemistries VS. Weak Extraction Chemistries

EPA draft method 1630 can has many interferences and sensitivities built into the extraction step. In EPA 1630, mercury analysis depends on an ethylation step, which causes mercury to volitalize out of the sample. However, the chemical used to ethylate mercury in the sample cannot outcompete several strong, natural ligands, such as thiol and chloride bonds. This causes a problem in samples with low mercury concentrations as well as samples with a lot of chloride and thiol groups.

The Quicksilver method uses Thiourea under conditions in which Thiourea outcompetes every other natural ligand. By using Thiourea, the Quicksilver method experiences no matrix interferences, unlike EPA draft methods. (Read more about our speciation chemistries in Technical Papers.)

Maintaining the Sample Matrix VS. Introducing Changes in Sample Chemistry

EPA draft method 1630 requires changes in the sample chemistry throughout the analytical process. In leaching mercury, the sample goes through acid distillation, solvent extraction, or matrix digestion. These procedures change the chemistry in the sample, and may convert species of mercury into other forms, such as volatile elemental mercury.

The Quicksilver method uses the same chemistry from sample preparation through analysis, allowing Quicksilver to precisely and accurately control the analytical conditions in the sample.