CH23 Vocab

Question 1

in chromatography, this parameter is T’r=tr-tm, where tr is the retention time of a solute and tm is the time for mobile phase to pass through the column

Answer 1

adjusted retention time

Question 2

a technique in which solute equilibrates between the mobile phase and adsorption sites on the stationary phase

Answer 2

adsorption chromatography

Question 3

a technique in which a particular solute is retained by a column by virtue of specific interaction with a molecule covalently bound to the stationary phase

Answer 3

affinity chromatography

Question 4

In chromatography, the parameter describing the shape of a peak. B is the distance from the peak apex to the back of the peak measured at 10% of peak height. A is the distance from the peak apex to the front of the peak at 10% of peak height. B/A = 1 is a symmetrical peak. B/A > 1 is tailing, and B/A < 1 is fronting.

Answer 4

asymmetry factor, B/A

Question 5

occurs in chromatography, when two adjacent peaks are sufficiently resolved that the signal between the peaks returns to the baseline. Allows determination of accurate peak areas.

Answer 5

baseline resolution

Question 6

a graph showing chromatography detector response as a function of elution time or volume

Answer 6

chromatogram

Question 7

net transport of a solute from a region of high concentration to a region of low concentration caused by the random movement of molecules in a liquid or gas

Answer 7

diffusion

Question 8

defined by Fick’s first law of diffusion: J=D(dc/dx), where J is the rate at which molecules diffuse across a plane of unit area and dc/dx is the concentration gradient in the direction of diffusion

Answer 8

diffusion coefficient

Question 9

in extraction, the equilibrium constant for the process in which a solute is partitioned between 2 phases: solute (in phase 1) and solute (in phase 2)

Answer 9

distribution constant, Kd

Question 10

for a solute partitioned between 2 phases, the distribution coefficient is the total concentration in phase 1.

Answer 10

distribution ratio

Question 11

what comes out of a chromatography column ; also called effluent

Answer 11

eluate

Question 12

solvent applied to the beginning of a chromatography column

Answer 12

eluent

Question 13

process of passing a liquid or a gas through a chromatography column

Answer 13

elution

Question 14

process in which a solute is transferred from one phase to another. Analyte is sometimes removed from a sample by extraction into a solvent that dissolves the analyte

Answer 14

extraction

Question 15

a technique in which the stationary phase has a porous structure into which small molecules can enter but large molecules cannot. Molecules are separated by size, with larger molecules moving faster than smaller ones

Answer 15

gel filtration chromatography

Question 16

same as gel filtration chromatography

Answer 16

gel permeation chromatography

Question 17

a technique in which solute ions are retained by oppositely charged sites in the stationary phase

Answer 17

ion-exchange chromatography

Question 18

motion with a parabolic velocity profile of fluid through a tube. Motion is fastest at the center and zero at the walls

Answer 18

laminar flow

Question 19

the distance per unit time traveled by the mobile phase

Answer 19

linear velocity

Question 20

diffusion of solute molecules parallel to the direction of travel through a chromatography column

Answer 20

longitudinal diffusion

Question 21

net movement of a molecule from one location to another by mechanisms such as diffusion, convection, and deliberate mixing . In chromatography, refers to the movement of solute between the mobile and stationary phases

Answer 21

mass transfer

Question 22

two liquids that a single phase when mixed in any ratio

Answer 22

miscible

Question 23

in chromatography, the phase that travels through the column

Answer 23

mobile phase

Question 24

a hollow capillary column whose inside walls are coated with stationary phase

Answer 24

open tubular column

Question 25

chromatography column filled with stationary phase particles

Answer 25

packed column

Question 26

a technique in which separation is based in differences in the solubility of sample components in the stationary phase in gas chromatography and in the mobile and stationary phases in liquid chromatography

Answer 26

partition chromatography

Question 27

length of chromatography column divided by plate number of the column

Answer 27

plate height

Question 28

dimensionless number indicative of column performance; calculated as the square of retention time of an analyte divided by the variance of the analyte band

Answer 28

plate number

Question 29

how close 2 bands in a spectrum or chromatogram can be to each other and still be seen as two peaks; in chromatography it is the difference in retention times of adjacent peaks divided by their width

Answer 29

resolution

Question 30

in chromatography, the adjusted retention time for a peak divided by the time for a mobile phase to travel through the column

Answer 30

retention factor

Question 31

the time from injection for an individual solute to reach the detector of a chromatography column

Answer 31

retention time

Question 32

the volume of solvent needed to elute a solute from a chromatography column

Answer 32

retention volume

Question 33

in chromatography, the ratio of adjusted retention times for two components

Answer 33

separation factor

Question 34

treatment of a chromatographic solid support or glass column with hydrophobic silicon compounds that bind to the most reactive Si-OH groups. It reduces irreversible adsorption and tailing of polar solutes

Answer 34

silanization

Question 35

a technique in which the stationary phase has a porous structure into which small molecules can enter but large molecules cannot. Molecules are separated by size with larger molecules moving faster than smaller ones. also called gel filtration, gel permeation, or molecular exclusion chromatography

Answer 35

size exclusion chromatography

Question 36

in chromatography the phase that does not move through the column

Answer 36

stationary phase

Question 37

H=A +B/ux + Cux
A depends on band broadening processes such as multiple flow paths
B depends on the rate of diffusion of solute in mobile phase
C depends on the rate of mass transfer

Answer 37

van Deemter equation

Question 38

the volume of mobile phase per unit time eluted from the column

Answer 38

volume flow rate