D L1: Sample Preparation

Question 1

what are the different types of biological samples?

Answer 1

Blood
Tissue 
Urine 
Vitreous humour 
cerebrospinal fluid

Question 2

what molecules are found in biological samples?

Answer 2

Deoxyribonucleic acid (DNA)
Proteins
Lipids
Metabolites

Question 3

what is sample extraction?

Answer 3

term used to describe the removal of the analyte from a matrix

Question 4

what is sample digestion?

Answer 4

term used to describe the destruction of the matrix to release the analyte

Question 5

whats the extraction equation?

Answer 5

(analyse)p1 arrow (analyse)p2

Question 6

How can equilibrium be changed?

Answer 6

by heat and solvents

Question 7

what’s a partition ?

Answer 7

analytes moving from one phase to another without any chemical changes

Question 8

what can k equal too ?

Answer 8

K= [𝐴𝑛𝑎𝑙𝑦𝑡𝑒]𝑃2/[𝐴𝑛𝑎𝑙𝑦𝑡𝑒]𝑃1

Question 9

what is k?

Answer 9

‘K’ is a ratio of the concentration of the analyte in Phase 2 to Phase 1

Question 10

Value of K depends on ______ of the analyte for each phase

Answer 10

affinity

Question 11

what are the phases?

Answer 11

Polarity (“like dissolves like”)
Volatility (headspace)
Hydrogen-bonding interactions
Ion-ion interactions
Ion-dipole interactions
Dipole-dipole interactions

Question 12

when you have the structure of your analyte what can you guess?

Answer 12

guess at predicting its polarity and hence choosing an appropriate solvent system

Question 13

polarity of organic molecules are ….

Answer 13

dictated by their functional groups

Question 14

Functional groups contain …..

Answer 14

contain polarised bonds which make the compounds polar

Question 15

whats headspace?

Answer 15

partition between liquid and gas

Question 16

whats Passive headspace

?

Answer 16

Equilibrium is constant or not disrupted

Question 17

whats Dynamic headspace ?

Answer 17

Equilibrium is disrupted (arrow) analytes driven into gas phase (or vapour phase)

Question 18

when is headspace analysis useful?

Answer 18

the separation of most volatiles from non-volatile liquids/solids

Question 19

what equipment is neededd for headspace analysis?

Answer 19

airtight container

airtight syringe

Question 20

what is the sample in headspace analysis?

Answer 20

vapour in the space above the liquid

Question 21

whats LLE?

Answer 21

liquid liquid extraction

Question 22

what does LLE give a measure of?

Answer 22

hydrophobicity

Question 23

whats the LLE equation?

Answer 23

KOW = [Analyte]octanol/[Analyte]water=[A]o/[A]w

Question 24

what usually reported from LLE?

Answer 24

Log Kow

Question 25

Octanol and Water are not _______

Answer 25

micible

Question 26

if log k ow is less than zero whats the phase?

Answer 26

hydrophilic, more in aqueous phase

Question 27

if log k ow is equal to zero whats the phase?

Answer 27

equal distribution between two phases

Question 28

if log k ow is greater than zero whats the phase?

Answer 28

hydrophobic (lipophilic), more in organic phase

Question 29

what can blood be classed as?

Answer 29

tissue

Question 30

can drugs be found in tissue?

Answer 30

yes

Question 31

How is the protein removed form the tissue?

Answer 31

removed by precipitation

Question 32

what are the 3 main methods of percipitating protein?

Answer 32

Organic solvents
Salting out
Isoelectric point

Question 33

what stops a protein from aggregating?

Answer 33

hydrophilic amino acids on surface create a hydration sphere

Question 34

how does organic solvent precipitation work?

Answer 34

• needs to be miscible in water
• disrupts hydration sphere
• proteins aggregate

Question 35

how does salting out precipitation work?

Answer 35

• add electrically neutral salt to sample
• reduces hyrdatation sphere, increases protein-protein interaction
• [rotein aggregates

Question 36

How does isoelectric point precipitation work?

Answer 36

• diff value for proteins
• adjust pH with acid/base
• isoelectric point forces cancel out
• attractive force dominates, protein aggregates
• selectively remove proteins

Question 37

Volatiles in a liquid (or solid) can be extracted using …..

Answer 37

Liquid (solid)-Gas extraction

Question 38

Non-volatile analytes can often be extracted by ?

Answer 38

liquid-liquid extraction or by removal of the proteins