IQ / OQ / PQ

Installation, Operational, and Performance Qualification

The sequence is cumulative, and each stage answers a different question. DQ asks whether the design will meet the user requirements before anything is bought. IQ asks whether what arrived is what was specified and is installed against the drawings, utilities, and materials of construction. OQ asks whether it operates across the full intended range — including alarms, interlocks, and worst-case limits, not just the normal set point. PQ asks whether it performs consistently over time using the actual product, load, or process.

A common and costly error is testing at the convenient middle of the range. OQ challenges the boundaries: minimum and maximum load, the fastest and slowest speed, the alarm conditions you hope never occur. If the qualification only proves it works where nothing is difficult, it has not qualified anything.

Qualification is upstream of process validation, not a substitute for it. Under the FDA lifecycle model, equipment and utility qualification sits inside Stage 2 alongside PPQ; EU GMP Annex 15 sets out the same DQ/IQ/OQ/PQ chain and expects it to be driven by a risk-based rationale rather than testing everything equally. ASTM E2500 pushes further, allowing verification effort to be concentrated where it protects product quality and patient safety.

• —DQ — the design will meet the user requirements (before purchase).
• —IQ — the system as installed matches the specification, drawings, and utilities.
• —OQ — it operates across the whole intended range, including alarms, interlocks, and worst case.
• —PQ — it performs consistently over time with real product or load.
• —Traceability to the URS is what an inspector follows — every requirement should land in a test and a result.
• —Requalification is triggered by change and by periodic review, not by the calendar alone.

EU GMP Annex 15 (Qualification and Validation, 2015 revision); FDA Process Validation: General Principles and Practices (2011) Stage 2; ASTM E2500-20 for a risk- and science-based verification approach; ISPE Baseline Guide Vol. 5 (Commissioning and Qualification, 2nd ed.).