Metrohm - Sample Preparation for VA: UV Digestion
Voltammetry, being highly specific, can deal with high salt loads. Organic contamination of a sample, however, can interfere with the VA trace analysis of heavy metals. The 909 UV Digester quickly and effectively breaks down organic molecules by UV photolysis, thereby enabling reliable determinations.
Suitable for transparent samples with low to medium organic contamination
Fully automatic simultaneous processing of up to 12 samples at a time
Low risk of sample contamination due to minute amounts of required reagents
Method recommended by standards
Controlled digestion temperature and time
After a small amount of H2O2 has been added to the sample as radical initiator, the sample is irradiated with UV light with wavelengths of 200 to 400 nm, producing OH radicals that spontaneously react with the organic molecules.
In the resulting radical chain reaction, all the organic molecules are broken down to low-molecular-weight compounds such as CO2, H2O, N2, or NH3, which do not interfere with VA analysis.
- DIN 38406, Part 16: Determination of zinc, cadmium, lead, copper, thallium, nickel, cobalt by voltammetry
- DIN 38406, Part 17: Determination of uranium – Method using adsorptive stripping voltammetry in surface water, raw water and drinking water
The 909 UV Digester handles your sample preparation fully automatically.
Up to 12 samples, arranged concentrically around the UV lamp to achieve uniform irradiation, can be treated at a time.
PTFE stoppers that are placed on the quartz sample vessels act as condensation fingers, preventing sample evaporation.
This also means that the 909 UV Digester can be used for sample preparation when analyzing samples containing mercury, arsenic, or selenium which are volatile at elevated temperatures or readily form volatile compounds.
The UV lamp that is at the heart of the 909 UV Digester generates heat; this is dissipated by a fan located in the base of the instrument. This air cooling has the advantage that no cooling water supply is needed.
The 909 UV Digester integrates in one housing the wet section and the control unit.
The latter serves the operation of the instrument and, via a display, provides information on the ongoing digestion. Users operating the instrument are protected from harmful UV radiation by a shield mounted on it.