: Bringing ISO Standards into Daily Practice
In a previous article, we looked at the international standards and principles defined in ISO 20391-1 and 20391-2. These ISO standards are an important foundation for ensuring the reliability of cell counting data. However, in real laboratory environments, applying ISO procedures to daily instrument performance checks (Daily QC) is often too complex and burdensome.
What researchers truly need is a practical verification tool that, while not as strict as ISO regulations, is simple, reproducible, and easy to use on a daily basis.
This is where the Validation Slide (BF, FL (형광)) comes in, together with the QC Mode built into Logos Biosystems’ LUNA-FX7™ and LUNA-BX7™ cell counters. The Validation Slide provides a straightforward way to verify the accuracy of instrument counts against the labeled concentration and viability values, while QC Mode allows results to be automatically logged, tracked through cumulative graphs, and exported as CSV files for management.
In short, when used together, these two tools enable researchers to implement the data reliability required by ISO standards in a simple, systematic way as part of their daily lab routine.
The greatest strength of ISO 20391-2 is that researchers validate their methods by directly measuring the actual cells they use, and then compiling statistical data. This makes it one of the most accurate and valid approaches available.
However, there are also several practical challenges:
In this article, we will focus on how these principles can be applied in everyday lab practice — specifically through the use of the Validation Slide and LUNA QC Mode.
For this reason, researchers often look for simple standard materials that can be used for Daily QC instead of real cells.
Of course, these materials cannot perfectly replicate the results of measuring live cells. Nevertheless, they are far more suitable for quickly confirming whether the instrument is maintaining stable performance.
Commonly used examples include NIST-traceable beads with known concentrations or fixed cells prepared for quality control purposes. However, these also have drawbacks—such as pipetting errors or uneven cell distribution within the counting chamber—which means multiple repeated measurements are still necessary.
The Validation Slide (BF/FL (형광)) is a standardized tool designed to verify instrument performance using the labeled concentration and viability values, instead of real cells. Since no sample preparation or pipetting is required, measurements are always performed under identical conditions, minimizing loading and distribution errors. This makes it highly advantageous for repeated QC checks.
Validation Slide (BF/FL): FL is a slide with fixed fluorescent beads, while BF is a semi-permanent slide with printed patterns—both can be used for instrument QC.
Why is it useful?
Compared with other reference materials, Validation Slides have lower cost and storage requirements, while making it easy to implement the QC concepts emphasized in ISO standards directly in the laboratory. They are particularly useful for:
Cumulative QC Result Graph: Repeated measurements remain consistently within the defined reference range.
QC Result Screen: Validation Slide measurement falls within the reference range (± 10 %), resulting in an OK judgment.
ISO 20391-2 is the most valid standard for verifying your method using the actual cells you work with. However, the procedure is complex and burdensome for daily QC. In contrast, the Validation Slide (BF/FL (형광)) is a simple and reproducible QC tool, well-suited for routine checks of instrument status.
The most efficient approach is:
By combining these two approaches, you can secure both the data reliability expected by ISO and the operational efficiency provided by the Validation Slide.
Validation Slides and QC Mode bridge the gap between the rigor of ISO standards and the practical efficiency of daily laboratory work.
Q1. How often should I use the Validation Slide?
A. It is recommended to use the Validation Slide before starting an experiment, after the instrument has not been used for an extended period, and whenever unexpected variability in results is suspected. The frequency can be adjusted depending on the research setting and project size.
Q2. Can the QC Mode acceptance criteria (±10%) be changed?
A. The default tolerance is set to ±10%, but this can be modified by the researcher when entering the Validation Slide information for the first time. Once the slide information is saved, the acceptance range cannot be changed, so it is important to set the criteria appropriately in advance.
Q3. Is the Validation Slide disposable?
A. The Validation Slide BF has no expiration date and can be reused as long as it is properly handled to avoid damage or contamination. The Validation Slide FL, on the other hand, has a specified expiration period, and it is recommended to replace it once that period has passed.
Q4. How are QC results managed?
A. All QC results are automatically saved in the instrument and displayed as cumulative trend graphs to monitor long-term performance. The results can also be exported, providing both graph images and CSV data files. This allows researchers to check performance trends visually and organize QC records or perform statistical analysis with the raw data. When needed, these results can also serve as objective evidence of reliability in research reports or publications.
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Logos Biosystems provides a diverse portfolio of automated cell counters designed to meet various laboratory requirements.
To learn more, visit www.logosbio.com.
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