How to Compile a Test Kit – Gunther Coenen

At eyetec, Gunther leads the technical operations, overseeing the VI/CCIT positive controls production, VI/CCIT consultancy and Pharma equipment after-sales support.  Gunther’s hands-on approach and deep understanding of production support and management complement the compliance expertise of his co-founder, Bram Keymolen (and Qualified Person) allowing eyetec to deliver comprehensive, compliant, and innovative solutions to its clients. 

Gunther is recognized in the industry as a Visual Inspection Subject Matter Expert.  

The Test Kit Compilation Process 

Can you walk us through the key steps in compiling a reliable test kit for Visual Inspection? 
Gunther Coenen: Absolutely. Compiling a reliable test kit starts with understanding the specific purpose of the test kit, the product family and container type. Each kit must be tailored to factors like container size, fill volume, and product characteristics. The process typically involves: 

• Initial risk assessment and definition of defect types and acceptance criteria 

• Defining the types of defects to include (e.g., particles, cosmetic, container defects) 

• Selecting both defect-free and intentionally defective units 

• Sourcing or creation artificial defect samples that realistically simulate production defects 

• Ensuring that the kit mirrors real-life production scenarios for training and validation 

• Assembling the kit and performing a blinded coding process 

• Validating the kit by running it through the intended inspection process and analyzing detection rates 

• Documenting everything for traceability and compliance 

• Regularly reviewing, validating and updating the kit as processes or regulations evolve 

What are the most important factors to consider for compliance and reliability? 
Gunther: Regulatory compliance is crucial. Test kits must meet GMP standards and regulatory expectations, such as those from the FDA and EMA. Reliability comes from using representative defects, maintaining kit integrity over time, and validating the kit’s performance in actual inspection processes. The kits should be robust enough for manual, semi-automated, and automated inspection systems.

Practical Insights and Examples 

Can you share a real-world example where a well-compiled test kit made a difference? 
Gunther: Certainly. We had numerous projects where the test set composition was not based on a risk assessment. This led to a composition that did not include all relevant defects, or included defects that were not relevant. As a result, manual visual inspectors were not trained and qualified properly, or automated visual inspection machines were engineered for the wrong defects, leading to non-conformities. By updating the risk assessment and redesigning their test kit to include the correct defect types and sizes, we improved either their inspectors’ Probability of Detection (PoD) and for automated visual inspection increased the detection rate and reduced the false rejection rate, leading to more reliable batch release decisions. 

What common mistakes do you see in test kit compilation, and how can they be avoided? 
Gunther: Common pitfalls include using non-representative defects, not updating kits as products or processes change, and neglecting documentation. Avoid these by regularly reviewing kit contents, updating risk assessments based on historical data, ensuring defects match real production issues, and maintaining thorough records for traceability. 

Expert Tips and Best Practices 

What are your top tips for QA and validation professionals? 
Gunther: My top tips: 

• Always base test kits on risk assessments where upstream processes and real product and defect data are used as input 

  Validate kits in the actual inspection environment 

  Involve both QA and production teams in kit design and review 

  Stay updated with regulatory changes and industry best practices 

How do you ensure compliance with evolving standards? 
Gunther: We monitor regulatory updates closely and participate in industry forums.  Regular training and audits also help maintain compliance. We do not only create test kits; if needed, we also advise our customers how we would ideally set up the test kit. 

What advice do you have for maintaining kit reliability over time? 
Gunther: Store kits under appropriate conditions, periodically revalidate them, and replace any units that degrade or become unrepresentative. Build maintenance and review into your quality system. 

Why should organizations invest in high-quality, validated test kits? 
Gunther: High-quality kits are essential for ensuring product safety and regulatory compliance. They support effective training and qualification of manual visual inspection personnel, reliable batch release, and robust engineering, performance qualification and process validation of automated visual inspection systems, reducing the risk of extraordinary false reject rates, recalls or regulatory findings. 

How does eyetec support clients in this area? 
Gunther: eyetec offers end-to-end support-from risk assessment and kit design to validation and ongoing maintenance. We provide tailored solutions for different defect types, container types and products, backed by our expertise in compliance and pharmaceutical operations. 

Are there any trends or innovations in test kit development you’re excited about? 
Gunther: Yes, we’re seeing more demand for kits tailored to Difficult to Inspect Products (DIP), new container types, such as infusion bags, and for mimicking products.