Top 25 QC Interview Questions and Answers for Pharma Freshers (HPLC, Dissolution, GLP)

Quality Control (QC) is one of the biggest hiring departments in any pharma plant. Whether you are a B.Pharm, M.Pharm, B.Sc or M.Sc fresher, the interview usually tests three things: basic analytical concepts, instrument knowledge and GMP/GLP discipline. Below are the questions interviewers ask most often, with short answers you can explain in your own words.

Basic QC concepts

1. What is the difference between QC and QA?

QC tests raw materials, in-process samples and finished products to check they meet specifications. QA builds and monitors the systems (SOPs, documentation, audits, change control) that make sure quality is designed into every step. Simply put: QC checks the product, QA assures the process.

2. What is a specification?

A list of tests, analytical procedures and acceptance criteria that a material or product must meet – for example assay 95.0–105.0% of label claim.

3. What is GLP?

Good Laboratory Practice – a quality system covering how lab studies are planned, performed, recorded, reported and archived, so that results are reliable and traceable.

4. What is OOS?

Out of Specification – a test result that falls outside the approved acceptance criteria. It must be reported immediately and investigated in phases: a lab investigation first (calculation, instrument, standard, sample preparation errors), then a full-scale investigation if no lab error is found.

5. What is OOT?

Out of Trend – a result that is still within specification but does not follow the expected trend, often seen in stability data. It is an early warning signal.

HPLC questions

6. What is the principle of HPLC?

Components of a mixture are separated based on their different affinity between a stationary phase (column) and a mobile phase pumped at high pressure. In reverse-phase HPLC, the column is non-polar (e.g. C18) and the mobile phase is polar.

7. What is system suitability?

A set of checks done before sample analysis to prove the system is working properly – typically %RSD of replicate injections, tailing factor, theoretical plates and resolution.

8. What causes peak tailing?

Column degradation, secondary interactions with silanol groups, wrong mobile phase pH, dead volume in connections or column overloading.

9. What is the difference between retention time and relative retention time?

Retention time is the time a component takes to elute. Relative retention time is the ratio of an impurity's retention time to that of the main peak – useful for identifying impurities.

10. Why do we degas the mobile phase?

Dissolved air forms bubbles in the pump and detector, causing pressure fluctuation, baseline noise and spikes.

Dissolution and other tests

11. What is dissolution and why is it important?

It measures how much drug is released from a dosage form into a medium over time. It predicts how the drug may behave in the body and checks batch-to-batch consistency.

12. Name the USP dissolution apparatus.

Apparatus 1 (basket), 2 (paddle), 3 (reciprocating cylinder), 4 (flow-through cell), 5 (paddle over disk), 6 (rotating cylinder), 7 (reciprocating holder). Apparatus 1 and 2 are the most common for tablets and capsules.

13. What is the difference between disintegration and dissolution?

Disintegration checks whether a tablet breaks into small particles within a set time. Dissolution measures how much drug actually goes into solution.

14. What is Karl Fischer titration used for?

Determining water content in a sample, based on the reaction of iodine with water.

15. What is the use of a UV-Visible spectrophotometer in QC?

Assay and dissolution testing of drugs that absorb UV/visible light, based on the Beer–Lambert law.

Stability, calibration and documentation

16. What are ICH stability conditions?

Common conditions are long-term 25°C/60% RH or 30°C/65% RH (or 30°C/75% RH for hot-humid zones) and accelerated 40°C/75% RH. The exact condition depends on the climatic zone of the target market.

17. What is calibration?

Comparing an instrument's readings with a known standard and adjusting it so results are accurate. Every instrument has a calibration schedule and a status label.

18. What is the difference between calibration and validation?

Calibration checks an instrument's accuracy. Validation proves that a process, method or system consistently produces the expected result.

19. What are the parameters of analytical method validation?

Specificity, linearity, range, accuracy, precision (repeatability and intermediate precision), detection limit, quantitation limit and robustness – as described in ICH Q2.

20. What is ALCOA+?

Data integrity principles: Attributable, Legible, Contemporaneous, Original, Accurate – plus Complete, Consistent, Enduring and Available.

Practical and HR-style questions

21. What will you do if you make an entry error in a logbook?

Strike it with a single line so it remains readable, write the correct value, sign and date it, and give a reason. Never overwrite, use correction fluid or tear pages.

22. What is a working standard?

A secondary standard qualified against a reference (primary) standard and used for routine analysis to save the costly reference standard.

23. Why do you want to join QC?

Connect your answer to your interest in analytical work, accuracy and instruments you handled during your degree or project.

24. Which instruments have you handled?

Be honest. Mention instruments you actually used in your college labs (UV, pH meter, dissolution, HPLC if any) and what you did with them.

25. Are you ready to work in shifts?

QC labs in manufacturing plants often run in shifts. Answer honestly about your availability.