System Simplifies Analysis for Trace Toxic Metals in Water

Safeguarding municipal water supply quality and monitoring wastewaters represents a major part of the workload at water and contract analysis laboratories. Important considerations are high analytical performance, which is needed to measure trace toxic metals like arsenic (As) in drinking waters at the current MDL's, together with an ability to handle the high concentrations and complex matrices often met with effluent analysis.

The wide analytical range required under current regulations means that flame, vapour and graphite furnace atomic absorption techniques may all be needed to cover the total measurement envelope. It also means that switching between the various atomisers will be required during the analysis process. For this reason the new generation of dual atomiser systems, such as the Thermo Elemental M Series, offer a more cost-effective solution to the problem than two single atomiser systems. The combined instrument occupies only about one third the space of multiple systems and with no loss in capability.

Thermo Elemental has developed the SOLAAR M Series AA, a dual atomizer atomic absorption spectrome

The very best dual atomiser systems permit the changeover to take place under software control and require absolutely no manual intervention. Flame/vapour and furnace autosamplers remain in place throughout the analysis, removing the need for re-alignment before any change of technique. Data-coded hollow cathode lamps enable spectrometer parameters to be selected automatically.

The Thermo Elemental M Series features wizard-driven SOLAAR analytical software that requires the absolute minimum of inputs to develop, store and run analytical methods. A selection of named QC test solutions, based on EPA requirements, may be used in an analysis. Method development is well catered for in the SOLAAR M Series.

Automatic optimisation of parameters, such as gas flow and burner height, help the user to extract the best flame performance while automatic selection of graphite furnace ash/atomisation temperatures simplifies this particular task. Further assistance is given in setting up furnace conditions with the GFTV accessory that permits the user to view sample behaviour inside the cuvette during the critical drying and ashing phases. Video images can be stored as proof of correct performance.

Versatility is also important. Thermo Elemental Zeeman-furnace systems, for example, also have deuterium background correction fitted as standard. The operator can then choose to use Zeeman or deuterium correction, depending on which method gives the best results. Background correction performance is especially important when dealing with wastewaters, where matrix interferences may be high All Thermo Elemental spectrometers come with a correction performance guarantee.

Graphite furnace performance is especially important in water analysis. The SOLAAR M Series furnace has an optical system tailored specifically for furnace analysis. The light beam is matched to cuvette dimensions so well that half-height furnace slits are not required to overcome potential emission effects. To this are added cuvette dimensions chosen to maximise sensitivity and accurate optical temperature control that allows temperatures up to the maximum 3000 oC to be used.

A recent innovation is the Omega platform cuvette which offers improved performance and longer lifetimes. The furnace autosampler has the full range of functions, such as multiple matrix modifiers, standards preparation, variable injection parameters, etc., likely to be necessary to give maximum flexibility while handling the widest range of sample types.

The combination of Omega cuvettes and the optimised furnace configuration results in improved performance. Current toxic metal MDL's can be attained, and with sufficient margin to spare that any future reductions in limits will not be a problem.

The 21 CFR Part 11 compliant SOLAAR software and optional system validation accessories ensure that meeting the various regulatory compliance issues is not a problem.