Automatic Trace Metal System (ATMS) - Elliott Webster

The Aquaco Automatic Trace Metal System (ATMS) is an instrument for detecting and measuring metals in water. The principal use is in the detection of pollutants such as mercury, copper, cadmium, lead, thallium and zinc, in the flow of water from, for example, rivers, drinking water and effluents. The principle is based on electrochemical voltage-current measurements. The ATMS can also measure other compounds such as pesticides.

Unlike competitive monitoring systems, the ATMS does not use chemicals and therefore does not pollute the sample water further. The result of this is that the sample can be returned to the water course and does not have to be disposed of separately.

This is crucial in the U.K. where it is unlawful to add even a small amount of pollution to a water course even for the purpose of testing contaminants.

The ATMS was invented, developed and patented by Professors Oyvind Mikkelsen and Knut Schroder of Trondheim University.

Several analytical methods are available for monitoring of the environment and industrial processes. Most frequently used is atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). However, very few methods can be adapted for use on-line in the field due to the fact that they are not sufficiently sensitive.

To date, the alternative solution has been to bring samples to laboratories to be analysed with sophisticated equipment. This is inconvenient, expensive and gives an undesirable time lag from the appearance of an accidental or illegal pollutant to the detection of it.

This summary paper describes an online monitoring system for heavy metals in normal water, seawater, waste and process water. The system is fully automated, and can be set up for remote transfer of the results via the internet.

Due to the low concentrations of the actual metal ions experienced in the field, the only suitable on-line analytical method that is sufficiently sensitive for this purpose is voltammetry or related dynamic electroanalytical techniques. Use of automatic methods will also enable one to act immediately upon environmental accidents or illegal effluents.

Voltammetry has some advantages compared to other techniques. It is a fast and easy analytical technique to carry out. The instrument is relatively inexpensive, and the operating costs are low. The system may be operational for several weeks or months without any maintenance. The high level of sensitivity allows for the detection limit of many important heavy metals to be as low as 0.5 – 1μg/L and even lower. Voltammetric methods cover concentration ranges down to drinking water requirements.

The introduction of silver based alloy electrodes has created new possibilities for constructing voltammetric apparatus for use in the field. It is now possible to construct apparatus with good stability over long periods of time for continuous remote surveillance of the level of heavy metals.