Flexible Tool for Aqua Regia Digestion of Trace Metals Recovery from Soil, Water and Electronic Waste

Heavy metals occur in various aspects of the environment like soil, water, sludge, waste, plants etc. They can easily enter the food chain and can cause endocrine disrupting effects. Unlike organic chemicals, metals do not degrade and have a greater tendency to accumulate in the environment. Cadmium (Cd), lead (Pb) and mercury (Hg) have strong endocrine disrupting effects and are therefore regulated in the RoHS directive (Restriction of the Use of Certain Hazardous Substances).

To protect the environment from these hazardous substances, the manufacturers of electric and electronic devices and components have to assure that their products are free of Cd, Pb, and Hg. The determination of these trace metals in complex matrices requires extensive sample preparation. The standard method DIN EN 62321 provides instructions to analyse sample material from waste electronics. The waste electronics are milled to a particle size less than 250 μm and digested with aqua regia under reflux.

The determination of heavy metals in soil and water is described in the standard methods DIN EN 13657, DIN ISO 11466, and DIN EN ISO 15587. Like the electronic waste material; soil, sludge and water samples have to be digested with aqua regia for two hours under a gentle reflux. The use of an absorption tube prevents the loss of volatile metals. Analysis by ICP-MS or other appropriate techniques are performed after filtration and dilution.

With BUCHI’s SpeedDigester coupled with a Reflux Digestion Set it is possible to digest up to twelve samples simultaneously under reflux with aqua regia. The SpeedDigester K-439 is the first digester that combines benefits of speed from IR (infrared heating) and temperature control from block digesters. The temperature controlled IR digestion together with an excellent thermal homogeneity ensures fast digestion leading to high reproducibility and reduced foam formation.

If samples are very inhomogeneous and representative digestions are required, the SpeedDigester excels due to the option to digest large sample volumes. The instrument allows the use of 300 ml and 500 ml sample tubes with the same instrument which is also ideal for applications with low detection limits.

In addition to aqua regia digestions, the SpeedDigester can be easily used in Kjeldahl determinations.

Find more information at www.buchi.com