If you're seeing unexpectedly high ATP readings, several factors could be at play. Here are some common issues to investigate:
Contaminated Pipette
Dirty pipettes can introduce contamination.
Solution:
Ensure regular maintenance with a monthly and annual cleaning schedule. Implementing a strict maintenance schedule could mean the difference between purchasing new, expensive equipment and relying on precise measurement instruments.
Dirty PhotonMaster Luminometer
A dirty luminometer (tube chamber) can cause high background readings.
Solution:
Clean the instrument regularly with the PhotonMaster Luminometer Maintenance Kit every 3-4 months, with an annual linearity check. When not in use, store the PhotonMaster in its field case to prevent accidental damage.
Contaminated Plastic Consumables
To ensure accurate results, the plastic parts used in 2nd Generation ATP testing must be sterile and free of ATP.
Solution:
Store unused parts in a clean environment in their sealed package. During use, prevent contamination of surfaces that come in contact with reagents or samples (e.g., avoid touching pipette tips on surfaces). If contamination is suspected, obtain a fresh, unused quantity and re-check background noise to confirm. Due to the risk of cross-contamination, these components are intended for one-time use only and should never be re-used. It's advisable to use the consumables supplied by LuminUltra whenever possible, as other materials may lead to elevated readings or be incompatible with the PhotonMaster/pipettes.
Light Exposure on Assay Tubes
The plastic assay tubes used in ATP testing are highly light-sensitive. When exposed to bright sunlight or intense indoor lighting, the plastics (polypropylene or polystyrene) can undergo photo-oxidation or heating. This causes them to emit their own light, which shows up as artificially high background RLUs. As can be seen in the chart below, elevated emissions can extend several minutes.
Solution:
Store tubes in their sealed packaging or an opaque container until use.
Keep tubes shaded during testing; avoid placing them near windows, ceiling lights, or hot surfaces.
Never use tubes that were left in direct sunlight or a hot vehicle; allow them to cool and use a fresh tube if needed.
Always close the PhotonMaster lid quickly after inserting a tube to shield the detector from ambient light.
Static Electricity Interference
Static electricity can disrupt ATP testing by creating electrical interference that affects the accuracy of readings.
Solution:
Ground yourself before conducting tests (a common way to do this is to touch a doorknob, faucet, or any conductive material connected to the ground), use a different brand of gloves, or anti-static wrist straps or move to a different location. Avoid wearing any PPE that can generate static electricity.
Light Saturation
The photodetector in the luminometer is highly light-sensitive and can become "saturated" with ambient light, especially in a standard laboratory setting. This can lead to consistently inaccurate readings over time.
Solution:
To prevent this, keep the lid of the PhotonMaster closed as much as possible. If light saturation occurs, one solution is to power down the luminometer and allow the photodetector assembly tube to return to normal over 4-6 hours.
Radio Frequency Interference
Electronic devices emit radio frequencies (RF), a type of electromagnetic radiation that can interfere with the luminometer's electronics. This interference can lead to higher-than-expected readings (RLUs). Common sources of RF interference include wireless internet connections, cellular phones, radios (VHF/UHF), cordless telephones, and heavy equipment such as motors or welding equipment.
Solution:
Avoid using the luminometer near these devices to prevent interference.
Helium Canisters
Helium gas can permanently damage a crucial component called the photomultiplier tube, which is responsible for detecting light and ensuring accurate readings.
Solution:
Avoid operating and storing the luminometer near Helium gas canisters to prevent this damage.
Other Common Issues
Confirm the PhotonMaster Luminometer was at room temperature during testing. A reading with a Luminometer directly from a hot truck or stored in sunlight or during winter can cause abnormal readings. Allow the device to return to room temperature before operating
Ensure the assay tubes and pipette tips are being stored in a clean environment
All reagents should be kept at room temperature (along with the equipment) before taking readings with a PhotonMaster.
Need Assistance?
For more detailed instructions, refer to the product manual or contact LuminUltra Support