Testing times

23rd January 2017

Posted By Paul Boughton

Is it time to reconsider how we approach compliance testing?

Markus Bernasconi offers a new perspective on compliance testing in food and pharmaceuticals

Rather than focusing on a specific application or parameter measured in analytical labs, certain circumstances I came across made me think just a little deeper.

When it comes to food safety and security, or even some batch release quality procedures in pharma and food, it is of tremendous importance that existing limits must not be exceeded to ensure safety for the consumer and quality properties of the product.

The first prominent issue here is that while questioning certain limits, e g. 0.82aw for water activity, no-one can always provide an answer as to why this limit was set: “It has just been done that way for many years.”

But have you ever thought about the possibility that you are measuring something that has limits of no context, just because it has always been done this way?

Naturally we all have a heavy workload and it might not actually be our responsibility to question either a certain established test method or its compliance limits. So it is important that we ask those who are responsible (internally, or maybe also the manufacturer of the sample material in question itself ) about new developments and maybe new findings, so that the implemented limits always reflect the current quality criteria and knowledge about the product.

Differing characteristics

The second issue relates to the indifferent performance and variability in external influencing factors. Each and every analytical technology has its own characteristic and things to consider before doing a measurement. In the majority of labs in the food and pharma sectors, it is all about “getting the job done, maybe getting a quick  result.” The school of thought here being, “As long as the values are within limits, we’re OK.” But have we thought about the fact that some measurements are influenced by the environmental conditions (such as temperature, air humidity, light) and that it is fundamental to respect those conditions to avoid wrong measurements? For example, although pH-value is automatically compensated to 25°C, water activity value cannot be and there is a different value at 20°C compared to a measurement at 25°C. Most users are often not concerned with what environmental conditions they measure at, as long as the value is within the limits set. What happens when the measured value is within limits but would have exceeded them at referenced environmental conditions (i.e. 25°C)?

Or have you thought about the fact that some measurements are not quite finished even if you get a stabilisation indicated on the screen? A lot of analytical technologies, especially in the field of physical or chemical analysis, depend on equilibrium within the sample or an exchange equilibrium with the environment in the measurement chamber. This is certainly the case with water activity, where the free water first has to come into equilibrium state with the air humidity in the chamber before the air humidity can be used for analysis and be linked to water activity mathematically.

To conclude, firstly we should all be ready to challenge old established compliance limits based on today’s knowledge about the product and technology we are using. Secondly, perhaps we should all be more mindful to respect the influencing parameters of each measurement and ensure that measurements are as reliable as possible by eliminating errors that may be caused by these environmental conditions.

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Markus Bernasconi is with Novasina


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