Chapter 4 - HPLC/UHPLC instrumentation and trends

Question 1

Some HPLC systems need to be biocompatible because of

Answer 1

the use of high-salt mobile phases that is corrosive to stainless steel.

Question 2

PEEK stands for

Answer 2

polyetheretherketone

Question 3

Multisolvent pumping systems are classified on how

Answer 3

solvent blending is achieved.

Question 4

The typical dwell volume of a low-pressure mixing HPLC system is

Answer 4

~ 1 mL

Question 5

Dwell time is important in _______ analysis.

Answer 5

gradient

Question 6

Dwell volumes of binary systems range from

Answer 6

0.1 to 0.4 mL.

Question 7

Dwell volumes of quaternary systems range from

Answer 7

0.4 to 0.8 mL

Question 8

Primary performance criteria for autosamplers is

Answer 8

sampling precision and carryover.

Question 9

Precision level of most autosamplers

Answer 9

<0.2% RSD for peak area

Question 10

Carryover of most autosamplers

Answer 10

<0.05%

Question 11

Minimum injection volume of HPLC

Answer 11

∼ 5 μL

Question 12

Minimum injection volume for UHPLC

Answer 12

∼ 1 μL

Question 13

An HPLC detector measures the

Answer 13

concentration of eluting analytes.

Question 14

Absorbance equation

Answer 14

Absorbance (A) = molar absorptivity (𝜀) × path length (b) × concentration (c)

Question 15

Absorbance is equal to _____ if 90% of the light is absorbed, and equal to _____ if 99% of incident light is absorbed.

Answer 15

1.0; 2.0

Question 16

A UV/Vis detector consists of

Answer 16

a deuterium lamp, monochromator, and a small flow cell

Question 17

The limit of detection in a PDA is

Answer 17

3x the noise.

Question 18

In a UV/Vis detector, sensitivity is specified by

Answer 18

baseline noise (peak-to-peak or root mean square noise).

Question 19

Typical UV/Vis wavelength range

Answer 19

190-600 nm

Question 20

A typical UV/Vis with a deuterium lamp has low sensitivity above ______ nm

Answer 20

400

Question 21

In UV/Vis, when a single wavelength is detected, between _______ nm usually passes through the flow cell.

Answer 21

5-8

Question 22

Benchmark detector noise level

Answer 22

±1 x 10^-5 AU/cm

Question 23

Typical lifetime of a deuterium lamp

Answer 23

∼2000 hours

Question 24

Preferred detector for HPLC method development.

Answer 24

PDA (photodiode array detector)

Question 25

Most PDAs have a spectral resolution of about

Answer 25

1 nm.

Question 26

Temperatures higher than 60^∘C are often used to allow

Answer 26

higher flow rates without exceeding system pressure limits by reducing solvent viscosity.