Calibration vs. Verification: What’s the Difference and Why It Matters

Calibration vs. Verification: What’s the Difference and Why It Matters

If you work with Modified Atmosphere Packaging (MAP), you know that maintaining the correct gas composition inside sealed packages is essential for product quality and shelf life. But when it comes to ensuring accurate readings from your MAP headspace gas analyzer, one question comes up repeatedly:

 What’s the difference between calibration and verification?

They sound similar, and both are essential, but they serve very different purposes. Confusing the two can lead to inconsistent results, failed audits, and even rejected product lots.

In this article, we’ll break down what calibration and verification really mean and how they work together to guarantee accuracy.

Why This Matters in MAP Headspace Gas Testing

Your headspace analyzer is a precision instrument. Whether it measures O₂, CO₂, CO, or all three, it must deliver accurate data to ensure your product’s gas composition meets specifications.

Without proper calibration and verification:

• O₂ levels may drift over time, making your product appear within spec when it’s not.
• CO₂ and/or CO readings might become unstable due to environmental or sensor changes.
• Auditors can flag missing traceability records, even if the device “seems fine.”

Ultimately, accuracy and documentation are what separate passing an audit from a compliance failure.

What Is Calibration?

Calibration is the process of adjusting your analyzer so that its readings match a known, certified standard. Think of it as teaching your analyzer what “truth” looks like. Certified calibration gas is the standard the analyzer should meet.

In calibration:

1. You introduce a certified calibration gas (e.g. 100% N₂, or a known CO₂ and CO mixture).
2. The analyzer compares its internal reading against that known value.
3. If there’s a difference, the instrument’s software or a technician adjusts the sensor output to realign it with the true value.

Calibration is essentially a correction - a way to bring the analyzer back to its baseline of accuracy.

Key facts about calibration:

• Uses certified reference gases with traceable concentration values. These are typically traceable to NIST.
• Adjusts the analyzer’s internal settings.
• Frequency will vary depending on verification results, environment, and usage.
• Documentation is required for ISO, HACCP, and FDA audits.

What Is Verification?

Verification is the process of checking that your analyzer is still reading accurately without making any adjustments. This is always performed more frequently than calibration and is the primary way to determine if you need to calibrate an analyzer.

In verification:

1. You test your analyzer using a known reference gas or a control sample.
2. If the reading matches the expected value within a set tolerance, your analyzer is acceptable for operational use.
3. If it’s outside tolerance, you investigate and possibly recalibrate.

Verification is like a spot check - it confirms performance between calibrations.

Key facts about verification:

• Uses the same certified reference gas as calibration.
• Does not change the analyzer’s internal calibration settings.
• Performed daily or weekly depending on the food item being packaged.
• Serves as early detection for drift or analyzer maintenance needs.

Calibration vs. Verification — The Core Difference

Why You Need Both

Calibration and verification aren’t interchangeable — they complement each other.

• Calibration ensures your analyzer can measure accurately.
• Verification ensures it is still measuring accurately.

Calibration establishes trust. Verification maintains it.

A Real-World Example

Your QA technician runs a daily verification using a certified 20% CO₂ gas. The analyzer reads 21.0% which is within tolerance. No problem.

A few days later, the same verification reads 25%. That’s a red flag.

At this point, your team performs a calibration using the same certified gas. After adjustment, the reading returns to 20%.

Without those daily verifications, you would have no idea your readings were off for several days, potentially affecting a large volume of product.

Regulatory and Audit Perspective

Food safety auditors - whether from the FDA, BRC, or a private customer - look for clear calibration and verification records.

Here’s what they typically expect:

• Documented calibration frequency based on product risk.
• Calibration certificates for reference gases (traceable to NIST or ISO standards).
• Verification logs showing regular performance checks.
• Corrective action records if a verification fails.

A good rule of thumb:

“If it’s not documented, it didn’t happen.”

Having both calibration and verification procedures (and proof of execution) is your best defense during an audit.

Conclusion

Calibration and verification work hand in hand to guarantee accurate, traceable MAP headspace analysis.

• Calibration aligns your analyzer with the true reference standard.
• Verification ensures that alignment holds true over time.

When you implement both and keep clear documentation you’ll not only maintain compliance but also build confidence in every reading your analyzer produces.

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For a verification & calibration standard operating procedure (SOP) template, request it using this Contact Us form. We will email an SOP and data logging spreadsheet template to you.

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