Practical ATP testing and sampling methodology – the latest evidence


Rapid testing for Adenosine Triphosphate (ATP) has become a commonly used method for quantitative assessment of surface or device cleanliness. ATP testing is an easy to use, broad measure of cellular contamination, and allows a real-time measurement of cleanliness.

ATP testing also has variability problems that affect the interpretation the results. This includes inherent variability arising from device causing imprecision, and difficulties with the limits of quantitation. The various brands of ATP testing devices lack interoperability and use different scales for the Relative Light Units (RLU) scale.

Sampling error remains a problem for all brands of ATP testing devices.

We propose a new sampling algorithm to help overcome unreliability with ATP testing results and interpretation.


To improve the validity of cleanliness measurements using ATP testing.


A reusable medical device study has been conducted with the new algorithm in addition to work using the sampling algorithm within the food sector. Application of the new algorithm in field studies has indicated a superior outcome in terms of data reliability.

The sampling algorithm uses three tiered, brand specific cleanliness thresholds, and a cleanliness verification step to ensure that surface cleanliness is verified using a validated cleaning method based on existing aseptic techniques. Statistical methods have been used to confirm the new sampling algorithm.


The results of the algorithm have indicated that the method is easy to use and provides the user a quantified, more accurate measurement of the real cleanliness status of surfaces and devices.

Authors: GS Whiteley; TO Glasbey

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