Introduction
Calibration is one of the most important steps in ensuring accurate ATP test results. At the microbiological level, knowing how active the enzyme is at the time of testing provides significant benefits for both data collection and interpretation. LuminUltra's 2nd Generation ATP test kids come with UltraCheck 1, a stable ATP standard solution at a concentration of 1 ng ATP/mL. This standard allows you to calibrate the Luminase enzyme before testing.
Why calibration matters
Accounts for enzyme activity: Luminase, like most enzymes, degrades over time. This results in a gradual decay in activity that can affect accuracy.
Protects accuracy under temperature stress: Enzyme degradation is strongly influenced by temperature. When ambient conditions exceed 30°C (86°F), enzymatic activity undergoes exponential decay. At 45 to 50°C (113 to 122°F), enzyme activity can be lost completely within one hour.
Normalizes data: By reacting Luminase with UltraCheck's known ATP concentration, you can measure the enzyme's current performance and adjust your readings to common scale.
Enables comparisons across time: With normalized results, you can reliably compare sample data across days, weeks, and even different locations.
How calibration works
Every ATP test produces light that is measured by a luminometer and reported in Relative Light Units (RLU). In an ideal world, enzyme performance would remain constant and unaffected by storage or environmental factors. In reality, enzyme degradation causes light output to decline over time.
Calibration and UltraCheck solves this problem. By providing the enzyme with a known concentration of ATP, you measure how much light it produces at the exact moment. This value tells you the enzyme's current activity level. You can use that information to standardize sample readings, ensuring they can be compared on a consistent basis.
Converting RLU to ATP concentration
Since the calibration involves using a standard with a known ATP concentration, you can convert light output (RLU) into ATP concentration (pg/mL or ng/mL). This conversation is integrated into LuminUltra's Relay Software, which automatically applies the appropriate dilution factors and sample volumes for your specific application.
This means your results are expressed in standardized mass-based units that can be compared to past and future data.
When not to use an enzyme vial
Each calibration provides an RLU value for UltraCheck that can be compared against the threshold in your kit instructions. If the calibration result falls below that threshold, the enzyme is no longer viable. In that case, discard the vial and rehydrate a new one to ensure maximum sensitivity and accuracy in testing.
How calibration supports data interpretation
Calibrated results can be compared against LuminUltra's interpretation guidelines provided in each kit. These guidelines offer a clear starting for determining whether your system is under good control or requires action.
For example in LuminUltra's QGA Test Kit:
These values help you interpret whether your system in good control or in need or corrective measures.
Best practices for calibration
Perform calibration once per day of testing
Calibrate for each set of samples analyzed together
Always calibrated when opening a new vial of Luminase
Use calibration to confirm enzyme viability before running field samples
In summary
Calibration is a quick but critical step that ensures confidence in your ATP results. It correct for natural enzyme decay, protects against the effect of temperature, standardizes data across time, and supports reliable interpretation with guideline values.
See: What is UltraCheck and how do I use it for ATP testing?
Need Assistance?
For additional support or to order kits, contact LuminUltra Support
By following these recommendations, your PhotonMaster luminometer will remain in excellent condition, delivering consistent, accurate results every time.