QC interview questions (with answers)
20 original QC interview questions with answers for Indian pharma freshers and candidates with up to 3 years of experience. Tap an option to check your answer, or open "Show answer".
1. What is the main purpose of a representative sample in QC?
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Answer: B — Sampling must be performed to a written plan so the results reflect the lot. A non-representative sample makes even a perfect analysis meaningless.
2. Which of these is a specification?
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Answer: A — A specification combines tests, references to analytical procedures and numerical limits or other criteria. Conformance to it is part of release.
3. In HPLC, which parameter describes how well two adjacent peaks are separated?
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Answer: C — Resolution measures the separation of two peaks. Tailing factor describes peak symmetry, and plate count describes column efficiency.
4. A tailing (symmetry) factor of 1.0 means the peak is
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Answer: D — A value of 1.0 indicates a symmetrical peak; values above 1 indicate tailing, and values below 1 indicate fronting. Limits are set in the monograph or method.
5. Why is system suitability tested in HPLC?
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Answer: B — System suitability is done with each analysis to check performance of the whole system. It does not replace qualification, calibration or method validation.
6. What is the difference between calibration and qualification?
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Answer: C — Calibration shows the accuracy of measurement against traceable standards. Qualification (DQ, IQ, OQ, PQ) shows overall fitness for intended use, and calibration is usually part of OQ/PQ and ongoing checks.
7. What is a working standard?
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Answer: D — Working (secondary) standards are characterised against a primary reference standard from a pharmacopoeia or other recognised source, and they are monitored periodically.
8. Under ICH Q1A(R2), what is the general-case accelerated stability condition for a drug product?
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Answer: D — The general-case accelerated condition is 40 °C / 75 % RH for a minimum of 6 months. The long-term condition is 25 °C / 60 % RH or 30 °C / 65 % RH, for at least 12 months at submission.
9. Under ICH Q1A(R2), when is intermediate testing at 30 °C / 65 % RH required?
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Answer: B — If the long-term condition is 25 °C / 60 % RH and significant change occurs during accelerated testing, intermediate testing is added. If 30 °C / 65 % RH is the long-term condition, there is no intermediate condition.
10. According to the FDA OOS guidance (2022), what is Phase I of an OOS investigation?
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Answer: C — Phase I is the laboratory assessment, for example of calculations, instruments, standards and analyst error. If no assignable laboratory cause is found, a full-scale investigation (Phase II) follows.
11. Which ICH Q2(R2) parameter expresses closeness of agreement between a series of measurements from the same homogeneous sample?
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Answer: A — Precision covers repeatability, intermediate precision and reproducibility. Accuracy is closeness to the true or accepted value.
12. Which parameter shows that a method can measure the analyte unequivocally in the presence of impurities, degradants and matrix?
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Answer: B — Specificity (selectivity) is the ability to assess the analyte unambiguously in the presence of expected components. Forced-degradation samples are often used to demonstrate it.
13. Which is a correct good documentation practice in the lab?
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Answer: C — Data is recorded contemporaneously and directly; errors are struck through with a single line, initialled, dated and explained. Blank spaces should be lined out or marked "NA".
14. An analyst notices an error in a notebook entry made yesterday. What should be done?
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Answer: D — The original entry must remain readable. This is basic data integrity practice (ALCOA).
15. What is the usual relationship between primary and working standards?
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Answer: B — Official standards (USP, Ph. Eur., IP) are used mainly to qualify working standards; the working standards are then used for routine analysis, which conserves the costly primary material.
16. Why should a sample for microbial testing be handled differently from a chemical sample?
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Answer: A — Microbial samples need sterile tools and containers and prompt testing to avoid false results from contamination or growth during storage.
17. An HPLC system suitability check fails (RSD above the limit). What is the right action?
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Answer: D — Sample results from a run with failed system suitability are not valid. The failure and investigation should be documented, and all injections kept in the data.
18. What does robustness of an analytical method show?
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Answer: B — Robustness examines small changes such as mobile phase pH, flow rate or column temperature, and indicates how reliable the method is in routine use.
19. What is a typical requirement for labelling a reagent or standard solution in the lab?
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Answer: A — Traceability of every solution is needed so that results can be linked to the materials used. The expiry period assigned should be justified (example in-house practice).
20. Why are retention (reference) samples kept?
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Answer: D — Retention samples allow a later check of a batch in case of a complaint or regulatory query. They are not for testing into compliance.