Chromatographic parameters MCQs With Answer

Chromatographic parameters MCQs With Answer provides M. Pharm students a focused way to master the critical metrics that govern separation performance and data quality in modern pharmaceutical analysis. This quiz set covers the fundamental and advanced parameters used in HPLC, GC, and related techniques, including retention factors, selectivity, resolution, efficiency (N, HETP), Van Deemter behavior, peak shape indices, and system volumes. You will also practice quick calculations, interpret performance trends, and identify which levers most effectively improve method robustness and sensitivity. Each MCQ emphasizes practical understanding for method development, validation, and troubleshooting, equipping you to make informed decisions on column choice, mobile phase optimization, flow conditions, and system configuration in real-world analytical workflows.

Q1. Which is the correct expression for the retention (capacity) factor k’ in liquid chromatography?

• (tR − t0) / t0
• tR / t0
• (tR − t0) / tR
• t0 / tR

Correct Answer: (tR − t0) / t0

Q2. The selectivity factor (alpha) for two peaks where compound 2 elutes after compound 1 is defined as:

• k’1 / k’2
• k’2 / k’1
• (tR2 − tR1) / t0
• (w2 − w1) / (w2 + w1)

Correct Answer: k’2 / k’1

Q3. What minimum resolution (Rs) is typically required for baseline separation in isocratic chromatography?

• Rs = 1.0
• Rs = 1.5
• Rs = 2.0
• Rs = 0.5

Correct Answer: Rs = 1.5

Q4. Which formula correctly gives the number of theoretical plates (N) using peak width at the base (wb)?

• N = 5.54 (tR / wb)^2
• N = 16 (tR / wb)^2
• N = 5.54 (wb / tR)^2
• N = 16 (wb / tR)^2

Correct Answer: N = 16 (tR / wb)^2

Q5. Which formula correctly gives the number of theoretical plates (N) using the width at half-height (w0.5)?

• N = 5.54 (tR / w0.5)^2
• N = 16 (tR / w0.5)^2
• N = 2.35 (tR / w0.5)^2
• N = 4 (tR / w0.5)^2

Correct Answer: N = 5.54 (tR / w0.5)^2

Q6. Height equivalent to a theoretical plate (HETP, H) is defined as:

• N / L
• L / N
• (tR / N)
• (N / tR)

Correct Answer: L / N

Q7. In the Van Deemter equation, which contribution decreases as linear velocity (u) increases?

• Eddy diffusion term (A)
• Longitudinal diffusion term (B/u)
• Mass transfer term (C·u)
• All terms increase with u

Correct Answer: Longitudinal diffusion term (B/u)

Q8. At high linear velocities, which Van Deemter term becomes the dominant cause of band broadening?

• Eddy diffusion (A)
• Longitudinal diffusion (B/u)
• Mass transfer (C·u)
• Detector response time

Correct Answer: Mass transfer (C·u)

Q9. Which parameter is specified by USP to quantify peak tailing measured at 5% of peak height?

• Tailing factor (T)
• Asymmetry factor (As)
• Resolution (Rs)
• Selectivity (alpha)

Correct Answer: Tailing factor (T)

Q10. The chromatographic asymmetry factor (As) at 10% height is defined as:

• a/b (front half-width divided by back half-width)
• b/a (back half-width divided by front half-width)
• w0.05 / (2f)
• (w1 + w2) / (tR2 − tR1)

Correct Answer: b/a (back half-width divided by front half-width)

Q11. For robust LC separations, the preferred range of capacity factor (k’) for target analytes is:

• 0.1 to 1
• 1 to 2
• 2 to 10
• 10 to 50

Correct Answer: 2 to 10

Q12. Which is the correct resolution (Rs) expression using peak widths at the base (w1 and w2)?

• Rs = (tR2 − tR1) / (w1 + w2)
• Rs = 1.18 (tR2 − tR1) / (w1 + w2)
• Rs = 2 (tR2 − tR1) / (w1 + w2)
• Rs = 0.5 (tR2 − tR1) / (w1 + w2)

Correct Answer: Rs = 2 (tR2 − tR1) / (w1 + w2)

Q13. Which strategy most effectively improves resolution in practice?

• Increasing column length to double N
• Decreasing flow rate slightly
• Increasing capacity factor k’ by 20%
• Altering mobile phase/column chemistry to change selectivity (alpha)

Correct Answer: Altering mobile phase/column chemistry to change selectivity (alpha)

Q14. If column length is doubled (other conditions unchanged), resolution (Rs) will:

• Double (2x)
• Increase by square root of 2 (~1.41x)
• Remain unchanged
• Decrease by half

Correct Answer: Increase by square root of 2 (~1.41x)

Q15. If tR = 6.0 min and t0 = 2.0 min, what is k’?

• 0.33
• 2.0
• 3.0
• 4.0

Correct Answer: 2.0

Q16. For a peak with tR = 5.00 min and w0.5 = 0.20 min, N (half-height method) is approximately:

• 690
• 3463
• 1600
• 10000

Correct Answer: 3463

Q17. The time an unretained compound spends in the system is best described as:

• Retention time (tR)
• Hold-up time (tM) or void time (t0)
• Dwell volume (VD)
• Gradient delay time (tG)

Correct Answer: Hold-up time (tM) or void time (t0)

Q18. In gradient LC, increasing the instrument dwell volume primarily causes:

• Earlier elution and shorter retention
• Longer apparent retention due to delayed gradient reaching the column
• Lower backpressure
• Higher selectivity (alpha) between peaks

Correct Answer: Longer apparent retention due to delayed gradient reaching the column

Q19. Increased extra-column volume (tubing, fittings, detector cell) mainly leads to:

• Higher selectivity between analytes
• Change in capacity factor k’
• Increased band broadening and lower efficiency
• Greater detector sensitivity

Correct Answer: Increased band broadening and lower efficiency

Q20. Common signal-to-noise criteria for detection limits are approximately:

• LOD S/N = 10; LOQ S/N = 3
• LOD S/N = 2; LOQ S/N = 5
• LOD S/N = 3; LOQ S/N = 10
• LOD S/N = 1; LOQ S/N = 2

Correct Answer: LOD S/N = 3; LOQ S/N = 10

Download