analytical separations

Question 1

chemical analysis

Answer 1

provides chemical information about the constituents in the sample

Question 2

typical sample consist of

Answer 2

analytes, matrix, and interference or interferent

Question 3

constituents of interest

Answer 3

analytes

Question 4

consist of all other constituents in a sample except for the analytes

Answer 4

matrix

Question 5

component species of the matrix that causes an error in an analysis by enhancing or attenuating the quantity being measured

Answer 5

interference or interferent

Question 6

a measure of a method’s freedom from interferences

Answer 6

selectivity

Question 7

techniques or reactions that apply for only a few analytes are

Answer 7

selective

Question 8

techniques or reactions that work for only one analyte are said to be

Answer 8

specific

Question 9

one important part of an analysis

Answer 9

dealing with interfering substances by separating analyte from the interfering species

Question 10

most powerful and widely used methods of treating interferences

Answer 10

separation techniques

Question 11

useful when there is a significant difference in at least one of the chemical or physical properties between analyte and interferences

Answer 11

separation techniques

Question 12

what are the separation techniques

Answer 12

1. filtration
2. centrifugation
3. masking
4. distillation; sublimation; recrystallization
5. precipitation; electrodeposition; volatilization
6. extraction; chromatography

Question 13

most basic physical property we can exploit in a separation

Answer 13

size

Question 14

uses a porous medium such as a filter paper or membrane through which only the analyte or the interferent can pass

Answer 14

filtration

Question 15

solution passing through the filter

Answer 15

filtrate

Question 16

material retained by the filter

Answer 16

retentate or residue

Question 17

used to separate particles that cannot be separated using filtration process

Answer 17

centrifugation

Question 18

factors affecting centrifugation separation

Answer 18

particle shape and viscosity

Question 19

the interference bind to a ligand forming a strong soluble complex that prevents it from interfering in the analyte’s determination

Answer 19

masking

Question 20

considered a pseudo separation technique bcs it can only chemically isolate the interference from the analyte

Answer 20

masking

Question 21

use to separate volatile analyte from nonvolatile interferent — separation due to difference in boiling point

Answer 21

distillation

Question 22

transition of a substance from the solid to the gas state

Answer 22

sublimation

Question 23

requires large solubility differences between analyte and potential interferences

Answer 23

precipitation

Question 24

metal can be purified from other metal by first dissolving it on appropriate acid and by application of a specific voltage a specific metal can deposit on an electrode

Answer 24

electrodeposition

Question 25

separation is based on the extent to which solute distribute themselves between two immiscible liquids

Answer 25

liquid-liquid extraction

Question 26

the liquid sample is passed through a cartridge that contains a solid absorbent

Answer 26

solid phase extraction (SPE)

Question 27

can retain low to moderate polarity species from organic matrices such as fat soluble vitamins; steroids

Answer 27

silica solid phase

Question 28

can retain hydrophobic species from aqueous matrices like caffeine, sedative, polyaromatic, hydrocarbons, carbohydrates, pesticides

Answer 28

octadecyl (C-18) solid phase

Question 29

common example of solid phase extraction

Answer 29

ion exchange

Question 30

a reversible chemical reaction wherein an ion from solution is exchanged for a similarly charged ion attached to an immobile solid particle

Answer 30

ion exhange

Question 31

high molecular weight polymers that contain large numbers of an ionic functional group per molecule

Answer 31

synthetic ion-exchange resins

Question 32

cation exchange resins and anion exchange resins contain what groups?

Answer 32

cation: acidic groups, anion: basic groups

Question 33

resin types

Answer 33

1. strong acid cation resins
2. weak acid cation resins
3. strong base anion resins
4. weak base anion resins

Question 34

continuous extraction process

Answer 34

soxhlet extraction

Question 35

why is continuous extraction conducted

Answer 35

bcs analyte with an unfavorable partition coefficient needs single extraction will not recover all the analyte

Question 36

most used supercritical fluid, sometimes modified by co-solvents such as ethanol or methanol

Answer 36

carbon dioxide (CO2)

Question 37

process of separating one component from another

Answer 37

supercritical fluid extraction

Question 38

substance at a temperature and pressure above the critical point and have both gaseous and liquid properties

Answer 38

supercritical fluid

Question 39

defined as a point on a phase diagram where both the liquid and gas phases of a substance have the identical density and are therefore indistinguishable

Answer 39

critical point