Use clean consumables, dedicated reagents, and careful bench habits. RNase contamination often appears as inconsistent downstream performance rather than an obvious visible failure.
Quality signals
Purity ratios, gel or instrument profiles, and downstream Ct behavior all provide clues. If the RNA is degraded, qPCR may still produce numbers, but those numbers can become hard to interpret.
Storage
Minimize freeze-thaw cycles and avoid leaving RNA at room temperature longer than needed. Aliquots are useful when a sample will be used across multiple experiments.
Reverse transcription context
The reverse transcription step is a major source of variability. Record RNA input, primer strategy, enzyme conditions, and whether genomic DNA removal was performed.
Practical checklist
- Use RNase-aware consumables.
- Keep sample handling time short.
- Record extraction date and storage history.
- Include no-RT controls when genomic DNA carryover matters.
- Interpret qPCR results together with RNA quality, not apart from it.
When to pause
If replicate spread is high, Ct values are unexpectedly late, or reference genes behave inconsistently, reassess RNA quality before changing only the qPCR calculation.