Chapter 3 - HPLC columns and trends

Question 1

Column support

Answer 1

Spherical/irregular, porous particles used as column packing material.

Question 2

Bonded phases

Answer 2

Stationary phase; support material modified with functional groups.

Question 3

Packing material

Answer 3

A term that can refer to both the support or the bonded phase.

Question 4

IBW

Answer 4

Instrumental bandwidth or system dispersion.

Question 5

Hybrid phases

Answer 5

Support synthesized from both inorganic and organic materials.

Question 6

SPP

Answer 6

Superficially porous particle.

Question 7

Dwell volume

Answer 7

Volume measured from the point of the solvents mixing in the HPLC system to the head of the column.

Question 8

Most common column length

Answer 8

150 mm

Question 9

Most common inner diameter

Answer 9

4.6 mm

Question 10

Most common particle size

Answer 10

3 μm C18

Question 11

Most common flow rate

Answer 11

1 ml/min

Question 12

Most common sample loading size

Answer 12

1 μg

Question 12

Most common sample loading size

Answer 12

1 μg

Question 13

Most common operating pressure

Answer 13

3000 psi or 200 bar

Question 14

Common column lifetime

Answer 14

2000 injections

Question 15

Void volume, sample capacity, and operating flow rate are proportional to

Answer 15

d_c²

Question 16

The limit of detection for minimum detectable mass is inversely proportional to

Answer 16

d_c²

Question 17

Longer columns have _______ plate counts and yield _______ resolution.

Answer 17

higher; better

Question 18

Since plate numbers are additive, columns can be connected in series to produce

Answer 18

higher efficiency and resolution at the expense of analysis time and mass sensitivity.

Question 19

Silica (SiO₂) is the dominant support material because of its

Answer 19

mechanical strength, modifiable surface chemistry, and high efficiency.

Question 20

Silica based bonded phases have a pH range of

Answer 20

2-8

Question 21

Most chromatographic supports are porous to

Answer 21

provide a high surface area to maximize the interaction of solutes with the bonded phase.

Question 22

Traditional problem areas of silica-based RPC columns.

Answer 22

• Batch to batch inconsistency
• Peak tailing of basic analytes
• Short column lifetime
• pH limitations

Question 23

Silanol group formula

Answer 23

Si-OH

Question 24

Hydrolysis

Answer 24

The reaction of an organic chemical with water to form two or more substances.

Question 25

Bulky groups are incorporated within the silane to

Answer 25

sterically protect the acid-labile Si-O-Si bonds against acid hydrolysis.

Question 26

Polar-embedded phases are not prone to phase collapse due to the

Answer 26

hydrophilicity of the polar-embedded group.

Question 27

An AQ designation of the bonded phase means

Answer 27

that the stationary phase is compatible with 100% aqueous mobile phases.

Question 28

Micro LC and nano LC benefits

Answer 28

• Increased mass sensitivity due to lower sample dilution
• Better compatibility with LC/MS
• Less solvent used

Question 29

Superficially porous particles (SPP) are made of

Answer 29

a solid, nonporous core surrounded by a porous shell layer.

Question 30

A guard column is a

Answer 30

small packed cartridge/column placed before an analytical column to protect it from contaminants.

Question 31

The standard determination of enantiomers is HPLC using _______ stationary phases.

Answer 31

chiral

Question 32

General guidelines for column selection.

Answer 32

• Select columns packed with 3- or sub 3 μm high-purity silica-bonded phases. Hybrids and SPP are highly recommended.
• For resolution of coeluting analytes on C18 columns, explore selectivity differences of polar-embedded, phenyl, PFP, or cyano phases.

Question 33

PFP stands for

Answer 33

Pentafluorophenyl

Question 34

SPP stands for

Answer 34

Superficially porous particles