HPLC

Q1: The eluent strength is a measure of

A solvent adsorption energy

B solvent absorption energy

C solvent diffusivity

D solvent mixing index

ANS:A - solvent adsorption energy

Please give the description of the answer.

Q2: HPLC stands for

A High Pressure Liquid Chromatography

B High Performance Liquid Chromatography

C both (a) and (b)

D Highly Placed Liquid Chromatography

ANS:C - both (a) and (b)

Answer is C because both pressure and perforce, answer are identified by HPLC.

Q3: A gradient elution in HPLC is one in which the composition of the solvent

A remains constant

B is changed continuously or in a series of steps

C both (a) and (b)

D none of the above

ANS:B - is changed continuously or in a series of steps

No answer description is available.

Q4: Column efficiency is measured in terms of number of plates which is

A inversely related to the square of the peak width

B directly related to the square of the peak width

C inversely related to the cube root of the peak width

D directly related to the square of the peak width

ANS:A - inversely related to the square of the peak width

[D]. Directly related to the square of the peak width.

Here, the square - should be cube root.

Q5: An eluotropic series

A ranks solvents by their relative abilities to displace solutes from a given absorbent

B ranks column packing material by their relative abilities to retain solutes on the column

C is a measure of the solvent adsorption energy

D none of the above

ANS:A - ranks solvents by their relative abilities to displace solutes from a given absorbent

A. Ranks solvents by their relative abilities to displace solutes from a given absorbent.

Here, absorbent - should be adsorbent.

Q6: Which of the following statements is true for a refractive index detector in HPLC?

A It is more sensitive than a UV detector

B It can only be used for isocratic elutions

C It does not respond to many solutes

D none of above

ANS:C - It does not respond to many solutes

The answer (C) is wrong. The correct one is B.

Refractive index is a physical constant which many compounds have NEARLY the same value.(similar to melting point) = not specific, respond to many compounds. C - WRONG.

If the mobile phase come along with very small amount of the analyte, no change in the signal (refractive index of the mobile phase is still the same) = not sensitive. A - WRONG.

But if the composition of mobile phase is changed (gradient), large amount (compare to the analyte) of quantity in the composition is change, then the signal (refractive index) will change due to the change in composition of mobile phase. This huge change will overlay the signal due to the analyte which is much less than mobile phase. B - CORRECT.

Q7: Void volume refers to the

A total volume of eluent in the column the remainder being taken up by the packing material

B the volume of solvent contained in a liquid chromatographic column

C the time required for the gradient to reach the column

D the volume of the column between the point at which solvents are mixed and the beginning of the column

ANS:A - total volume of eluent in the column the remainder being taken up by the packing material

No answer description is available.

Q8: Which can be used as a mobile phase in HPLC applications?

A Any compound with solubility in liquid

B Any compound with limited solubility in liquid

C Any compound with non-solubility in liquid

D Any of the above

ANS:A - Any compound with solubility in liquid

No answer description is available.

Q9: In reversed phase HPLC, there is a

A non polar solvent/polar column

B polar solvent/non-polar column

C non polar solvent/non-polar column

D any of the above

ANS:B - polar solvent/non-polar column

Please describe the given answer.

Q10: Dwell volume is defined as

A the volume of solvent contained in a liquid chromatographic column

B the time required for the gradient to reach the column

C the volume of the column between the point at which solvents are mixed and the beginning of the column

D none of these

ANS:C - the volume of the column between the point at which solvents are mixed and the beginning of the column

No answer description is available.

Q11: An isocratic elution in HPLC is one in which the composition of the solvent

A remains constant

B changes continuously

C changes in a series of steps

D none of these

ANS:A - remains constant

Explain the answer, please.

Q12: For a typical adsorbent such as silica gel, the most popular pore diameters are

A 10 and 50 A°

B 60 and 100 A°

C 100 and 150 A°

D 150 and 200 A°

ANS:B - 60 and 100 A°

No answer description is available.

Q13: HPLC methods include

A liquid/liquid (partition) chromatography

B liquid/solid (adsorption) chromatography

C ion exchange and size exclusion chromatography

D all of the above

ANS:D - all of the above

No answer description is available.

Q14: In normal phase HPLC, there is a

A non polar solvent/polar column

B polar solvent/non-polar column

C non polar solvent/non-polar column

D any of the above

ANS:A - non polar solvent/polar column

No answer description is available.

Q15: Which of the following(s) is/are the advantage of HPLC over traditional LPLC (low-pressure liquid chromatography)?

A Greater sensitivity and reusable columns

B Ideal for ionic species and large molecules

C Sample recovery

D All of the above

ANS:D - All of the above

No answer description is available.



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