Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Separation Techniques > UNIT 1 > Flashcards

UNIT 1 Flashcards

1
Q

What is a food matrix

A

complex nonhomogenous mixtures of many chemical substances, natural & synthetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

True/false: only processed foods are complex food matrices

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are some naturally occurring chemicals in food?

A

water, carbs, AA, peptides, lipids, vitamins, flavors, inorganic components…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Examples of synthetic substances in food:

A

functional additives, food coloring, flavorings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

food may be contaminated with undesirable chemical substances such as:

A

environmental contaminants
process induced contaminants
agrochemical residues
food contact material residues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The component of interest to be analyzed is called the _____

A

analyte

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the ‘matrix effect’

A

combined effect of ALL components in the sample (other than analyte) on measurement of the analyte (interference)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The sample is composed of the analyte contained in the ____

A

matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are molecules classified according to size?

A

small: low molecular wt (<900Da) - simple sugars, AA, FA

large: (100000s of Da)
Protein, complex carbs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

True/False: hydrophobicity is the same thing as lipophilicity

A

False:
often used interchangeably, but not exactly the same thing
(hydrophobic - doesn’t like water; lipophilic - likes fat)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Example of compound that is hydrophobic but not lipophilic:

A

fluorocarbons

hydrophobic and lipophobic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does ‘polarity’ refer to?

A

solubility
polar: soluble in water, protic organic solvents (hydrophilic)

nonpolar: soluble in nonpolar organic solvent (hydrophobic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

examples of polar compounds:

A

simple sugars, oligosaccharides, AA, small protein/peptide, B and C vitamins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

examples of nonpolar compounds:

A

fats, PL, sterols, A, D, E, K vitamins, carotenoids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

hydrophobicity of a compound can be expressed as a ______ coefficient

A

Octanol-Water partition coefficient

Kow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

When a chemical is hydrophobic, Kow will be (low/high)

A

high

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How do you calculate Kow?

A

ratio of concentration in octanol vs concentration in water

in separatory funnel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the units of Kow? how is it usually expressed?

A

no unit

log Kow

19
Q

A chemical with log Kow = 5.66 is (hydrophobic/hydrophilic)

A

hydrophobic

20
Q

caffeine should have a (high/low) log Kow

A

low

21
Q

How is the ‘solubility of a solute’ defined?

A

proportion of solute in designated solvent, when saturated (max amount that can be dissolved)

expressed in concentration, molality, mole fraction, etc

22
Q

Classifications of compounds according to volatility:

A

nonvolatile: (low vapor pressure/high boil pt) - sucrose, NaCl

Volatile: (high vapor pressure, low boil pt) - essential oil, low mol. wt FA, flavor compounds…

23
Q

Challenges of food analysis: (3)

A

complex matrices
varied compositions among samples
need to be fast (maintain sample integrity, respond quickly to clients)

24
Q

some technologies that allow rapid analysis, without manipulation: (5)

A 
X ray fluorescence
Infrared spectroscopy (FTIR, NIR)
Guided Microwave Spectrometry (GMS)
MRI
Direct Analysis in Real Time (DART) MS
25
Q

Advantages of rapid analysis techniques:

A 
no sample prep
automated
convenient
rapid
can be done in-process
nondestructive
safer, no hazardous chemicals
efficient - less energy/manpower/chemicals
26
Q

What technology can be used for in-process analysis, and is even starting to be adapted for smartphones?

A

Near Infrared Technology

27
Q

What technology can be used for elemental analysis, and what are its advantages?

A

total reflection xray fluorescence

little to no sample prep
little sample needed (few ug/uL)

28
Q

What can be analyzed with the portable handheld XRF scanner?

A 
monitor preservative Ca coatings
elemental nutrient verification
animal feed assessment/risk analysis
analyze salt/sodium compounds in salty snacks
milk/dairy/powder analysis for Fe and Ca
Salt analysis for Iodine
29
Q

Current limitations of direct analysis:

A

low sensitivity and selectivity
surface vs bulk composition
not standardized or approved
instrument cost

30
Q

What is the definition of separation?

A

separating components of a mixture without modifying them substantially

31
Q

Carl Wilhelm Scheele was the first to do what?

A

separate citric acid by crystallizing it from lemon juice

32
Q

What is partial vs complete separation?

A

partial: isolate one component of interest, others remain mixed
complete: isolate all different components

33
Q

Separations can be done based on what physicochemical characteristics?

A

size/mass
charge
polarity
volatility

34
Q

Partitioning, also known as _____, describes what process?

A

distributing

solute is distributed amount phases (reaching equilibrium); certain % in each phase

35
Q

What is adsorption?

A

distribution processes occurring between solute and the SURFACE of the phase

36
Q

What is absorption?

A

distribution processes occurring between solute and the BULK of the phase

37
Q

What is equilibrium?

A

system reaching a state where the properties (activity, concentration, etc) remain unchanged

*driving force for many separations

38
Q

The 2 types of ‘driving force’ for separations:

A
  1. equilibrium (system tries to attain equilibrium)

2. nonequilibrium (kinetic): rate at which solutes migrate provides driving force

39
Q

Differential centrifugation is what type of separation? (driving force)

A

kinetic

separation caused by particles moving at different rates due to various density/sizes

40
Q

In differential centrifugation, the (more/less) dense particles will reach the bottom first

A

more

41
Q

examples of equilibrium driven separation techniques:

A 
partition chromatography
Extraction
distillation
precipitation
crystallization
42
Q

examples of kinetic driven separation techniques:

A 
dialysis
electrophoresis
exclusion chromatography
centrifugation
filtration
sedimentation
membrane methods
43
Q

what are hybrid/hyphenated techniques?

A

combination of instrumental methods

GC-MS, LC-MS, SPE-HPLC, CE-FTIR…

Separation Techniques (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions