The 4th generation of ATP tests is now available!
ATP testing is a very easy-to-use field method, used since the 80s. It gives an estimation of the water microbiological quality. ATPmetry measures the total flora contained in a water sample in less than 2 minutes. First qualitative, then quantitative, this technique never stopped evolving to become one of the most reliable, reproducible and relevant tests for monitoring of water circuits.
1st generation ATP test, or qualitative ATP test, exists since the 80s. Very easy-to-use, this method generally uses a pen-sized sample collection device composed of a swab or comb for sampling, and reagents in the upper part. The bioluminescence measurement only takes a few seconds using a luminometer. The result is given in RLU (Relative Light Unit).
2nd generation ATP test includes the measurement calibration using an external standard. The result is then quantitative, in picogram of ATP. A filtration step is often added to concentrate the sample. Consequently, the sensitivity is increased, the sampling is more representative while free ATP is eliminated. However, these 2nd generation ATP kits generally require a dilution step which significantly decrease the sensitivity.
3rd generation ATP test uses an internal standard. In this way, all the environmental constraints acting on the enzyme are taken into account for each sample (temperature, pH, salt concentration, inhibitors…). This evolution makes quantitative ATPmetry more reliable and sensitive. Indeed, the dilution step is suppressed. Furthermore, the use dropper bottles makes these kits more user friendly.
The main remaining default of ATP test was the storage of reagents at 4°C. This 4th generation of ATP test involves freeze-dried reagents. Now, the kit can be stored at room temperature and stay stable for months. All of this preserving the qualities of the 3rd generation of ATP test!