This article explores the practical differences between centralised laboratory testing and decentralised point‑of‑need testing, using chilli heat (Scoville Heat Units, SHU) as a concrete example. It examines where uncertainty enters analytical workflows, why different laboratories can produce very different results from the same sample, and how modern electrochemical sensing platforms are reshaping expectations around speed, transparency, and reproducibility.
Centralised vs Decentralised Testing Models
The traditional laboratory model
Centralised laboratories rely on sophisticated analytical platforms—HPLC, GC, mass spectrometry—operated by trained specialists. In principle, this delivers high sensitivity and selectivity. In practice, however, results depend on a long and complex workflow, including:
- Sample collection and packaging
- Transport and storage
- Weighing, dilution, extraction, and filtration
- Standing times before analysis
- Instrument calibration and data processing
Each step introduces potential variability. By the time a single numerical result is returned, the original context of the sample is often lost.
Point‑of‑need testing
Decentralised testing moves analysis closer to where samples are produced or decisions are made. Using compact electrochemical sensor platforms, measurements can be performed immediately after preparation, by the same team that collected the sample.
✅ The defining difference is custodianship: the user maintains full visibility and control over what happens to the sample from start to finish.
Why Laboratory Workflows Add Uncertainty
A common assumption is that sending a sample to a laboratory guarantees “the truth”. In reality, laboratories rarely return raw analytical signals or full methodological transparency.
The HPLC “black box”
HPLC does not directly output concentration. Instead, it produces a chromatogram—absorbance versus time. Converting that signal into a reported value requires:
- A valid and recent calibration curve
- Correct peak identification and integration
- Assumptions about extraction efficiency and analyte stability
📌 Most clients receive only the final number, not the chromatogram, calibration details, or uncertainty budget.
Sample handling effects
Organic compounds, such as capsaicinoids in chilli, can:
- Adsorb onto plastic or glassware
- Degrade over time
- Precipitate or separate during storage
Without visibility into standing times or preparation steps, it is impossible to know how representative the analysed aliquot truly is.
A Real‑World Comparison: Same Sample, Three Laboratories
To test these assumptions, a client sent identical chilli powder samples to three different laboratories:
- Two commercial labs
- One national (government‑run) laboratory
The results differed dramatically:
- Sample 1: 23,500 SHU to 50,000 SHU
- Relative standard deviation between labs: up to 38%
Even across four samples, none of the three labs produced identical results. While two commercial labs showed some correlation, the national lab—more transparent and collaborative—stood apart.
🔬 This highlights a critical point: instrument sophistication does not eliminate workflow‑driven variability.
Correlation with Point‑of‑Need Electrochemical Testing
The same samples were also analysed using a decentralised electrochemical sensing platform (FoodSense Generation 4).
Key observations
- Results correlated strongly with the national laboratory
- Regression coefficients showed good agreement
- Most samples fell within ~20% relative deviation
For example:
- National lab result: ~50,000 SHU
- Point‑of‑need result: ~55,000 SHU
💡 For many food industry applications, this level of agreement is not only acceptable—it is operationally transformative when paired with speed and transparency.
Why Custodianship Matters
Performing analysis at the point of need offers several practical advantages:
✅ Immediate feedback on sample preparation
✅ Ability to correct dilution or handling errors in real time
✅ Full visibility of the raw measurement process
✅ Rapid, low‑cost decision‑making
Rather than replacing central laboratories, decentralised testing complements them—particularly for screening, quality control, and process monitoring.
Practical Takeaways
What this means in practice
- Do not assume inter‑lab agreement: identical samples can yield very different results
- Ask for transparency: chromatograms, calibration details, and uncertainty matter
- Match the tool to the decision: not every decision requires a delayed, centralised assay
- Value speed and context: rapid results with known provenance can outperform slow “gold standards”
When point‑of‑need testing excels
- Incoming raw material checks
- Batch‑to‑batch consistency
- Process optimisation
- Distributed, multi‑site operations
⚙️ Modern electrochemical platforms allow consistent methodologies to be deployed globally, reducing dependence on external laboratories.
Relevant Instrumentation
The decentralised testing approach discussed here is enabled by compact electrochemical instrumentation, such as:
- SenseItAll Generation 4
https://shop.zimmerpeacock.com/en-gb/products/senseitall-sia-generation-4-device-only
These systems are designed for rapid, repeatable measurements directly at the point of need, while maintaining traceability and scientific rigour.
Closing Thoughts
Accuracy is not just a function of expensive equipment—it is shaped by workflow design, transparency, and custodianship. As food testing becomes more distributed and time‑critical, organisations are increasingly re‑evaluating how and where measurements should be made.
If you are exploring point‑of‑need testing, laboratory correlation, or sensor‑based food analysis, thoughtful discussion and collaboration are often the best starting point.
📌 To continue the conversation or explore practical applications, you can get in touch here:
https://www.zimmerpeacock.com/contact
