The Discrete Analyser is no different, being initially designed as a clinical analyser, and later presented to environmental users as a way to reduce costs, increase throughput and reduce waste in laboratories.
In the early 2000's SEAL Analytical was formed as the environmental arm of Synermed- a clinical UK based company. SEAL quickly found obstacles to using clinical analysers in environmental markets, and they subsequently designed a Discrete Analyser to overcome these obstacles.
The result is the AQ2 Discrete Analyser - an analyser designed specifically for environmental analysis. Today SEAL has the largest installed base of Discrete Analysers in the USA and they continue to develop the software and hardware for the specific needs of environmental users.
The main clinical analyser design issues addressed by the SEAL AQ2 Discrete Analyser:
- The Mixing of Samples and Reagents- mixing of samples and reagents is critical, however in some analysers it is not very effective, which means the results are not reproducible. Instead, the AQ2 approximates mixing in a flask by repeatedly “sucking and spitting” samples and reagents, rather than simply stirring. The SEAL approach is the most effective way to mix, and it limits moving parts.
- Cross Contamination- with Discrete Analysers using the same probe to pick up samples and reagents and flicking droplets over the system, the cross contamination of cells is a real possibility. The AQ2 completely negates cross contamination opportunities by being the only discrete analyser with 3 wash stations, including flushing of the probe (on the outside before it moves anywhere) and a fixed wash pot that is continually filled with fresh DI water. This means the AQ2 is the only Discrete system that can run nitrate and ammonia together with no cross contamination (as nitrate uses NH4CI buffer).
- Cuvette Path Length- most Discrete Analysers used in clinical tests use a shorter path length (6 or 7mm), important in clinical tests where reactions are enzymatic, and reagents so expensive (the smaller the cell, the less reagent us used). These shorter path lengths lower the signal and result in a higher detection limit. The AQ2 includes the accepted and optimum EPA path length of 10mm, which results in lower detection limits, critical for environmental analysis.
- Styrene Cuvettes- many Discrete Analysers use styrene reaction wells from which measurement is taken. These are not only more expensive (increasing the cost per test), they scratch easily and are not optically pure, leading to reproducibility issues. The AQ2 uses low cost, disposable reaction wells and measurement is performed in 100 per cent optically pure glass cuvette.
- Higher Detection Limits- most Discrete Analysers not designed specifically for environmental applications have higher detection limits resulting from the combination of mixing techniques, shorter path lengths, and non-optical cells.
- Reproducibility- all clinical analysers are direct read. SEAL was aware that flow systems gave the lowest and most reproducible results and ensured this design feature was included in the AQ2. The AQ2's readings are done in:
- 100 per cent optically pure glass cuvette (which is not a consumable, and it stays in the detector)
- With each sample read in exactly the same position, resulting in no alignment issues
- Inert and easily cleaned glass, with a blank measurement done between each sample
- A Hellma cuvette, which is exactly the same as those used in spectrophotometers (it is not a flowcell)
- A static sample, which is then washed out thoroughly, a blank done and then the next sample is put in
Discrete Analysers available for all size laboratories- from small laboratories with small runs through to larger laboratories needing to run up to 180 tests in a run.
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