quiz#6 Terms Flashcards

1
Q

types of liquid chromatography:

A

1) partition
2) ion exchange
3) adsorption
4) size-exclusion

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2
Q

partition LC

A

analytes with varying palarity interact with a nonpolar stationary phase and aqueous mobile phase

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3
Q

ion exchange LC

A

analytes with different charges/charge densities are resolved by a charged stationary pahse

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4
Q

adsorption LC

A

analytes preferentially adsorb to a solid support

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5
Q

size-exclusion LC

A

sort by the size of the molecule (good for macromolecules)

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6
Q

t0

A

time of totally unretained solute; velocity = u0:

H2O

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7
Q

t1

A

time of somewhat retained solute; velocity u1:

MeOH

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8
Q

t2

A

time of somewhat more retained solute; velocity u2:

PrOH

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9
Q

retention

A

a way to describe the length of time an analyte spends on its column relative to its length

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10
Q

how is retention reported?

A

capacity (retention) factor:

k1= (tr-t0)/(t0)

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11
Q

selectivity factor

A

a= KB/KA

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12
Q

column performance :

A

-efficiency= # of theoretical plates AKA # of partitioning opportunities
-HETP=height equivalence to a theoretical plate – H=L/N OR N=L/H
SMALLER HEIGHT = BETTER!

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13
Q

Gaussian peaks

A

N= (tr/s)^2

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14
Q

asymmetric peaks

A

if tailing : assymetric factor/ratio =T=B/A

N=((4.17tr^2)/(1/10w^2))/t+1.25)

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15
Q

real samples

A

implies that some degree of sample preparation will be required

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16
Q

neat samples

A

run as is

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17
Q

procedure for sample prep

A

LOT/Gross–> representive bulk sample–>homogenous lab sample–>aliquots–>analysis

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18
Q

BIG 5 Qs?

A
1- how much sample
2- where to pull withing the sample pool 
3- how much of each sample 
4-how to minimize error in sampling 
5-what kinds of samples to get
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19
Q

types of sampling:

A

1-random
2-biased(judgemental)
3-systematic

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20
Q

ways to sample:

A
  • grab
  • composite
  • in-situ
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21
Q

grab

A

taditional taking a lot

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22
Q

composite

A

multiple grabs from multiple times and then sampled

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23
Q

in situ

A

many tiny pulls from a sampling stream (flow injection analysis)

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24
Q

How many samples to collect?

A

nsamples= (t^2s^2)/e^2

25
Q

direct analysis

A

get the mass of analyte directly

26
Q

indirect analysis

A

measure the mass of a related compound and then calculate the mass

27
Q

traditional [analysis]

A

involves the precipitation of your analyte

28
Q

what is the key to gravimetric analysis?

A

conservation of mass!

29
Q

what is so great about gravimetric analysis?

A

it is a definitive technique! aka its not derived, but rather, it uses base SI units

30
Q

steps in GA

A
1-prepare your sample solution
2-precipitation of the analyte
3-digestion
4-filtration
5-washing
6-drying/ignition
7-weighing
8-calculation
31
Q

% analyte (w/w)

A

(mass of analyte(x)/mass of sample)x100

32
Q

colloids

A

particle of size 10-100nm

33
Q

electrical double layer

A

++++++

34
Q

gooy chapman layer

A
layer of non-randomness 
----------
\++++++
----+----
\++-++-+
35
Q

zeta potential

A

the charge that desists* on a colloidal particle

36
Q

types of impurities:

A

1) inclusions
2) occlusions
3) surface adsorption

37
Q

inclusions

A

impurities scattered within the crystal lattice

38
Q

occlusions

A

impurities within the crystal lattice that a large/ clustered

39
Q

surface adsorption

A

impurities of the surface

40
Q

co-precipitation

A

this is the generic term for any incorporation of impurities in ion crystal lattice –> inclusions/occlusions/surface adsorption

41
Q

How do you solve surface adsorption?

A

1- wash your crystals

2-digestion!- allow precipitate to settle in mother liquor for a long time with slow temperature change

42
Q

Types of Filtration:

A

1) fast
2) medium
3) slow
4) ashless

43
Q

fast filtration

A

pore size~20microm

44
Q

medium filtration

A

pore size~15microm

45
Q

slow filtration

A

pore size~2microm

46
Q

ashless filtration

A

leaves you with 0.1mg or less

47
Q

drying

A

oven@110*C

48
Q

ignition

A

fire!

49
Q

slurry

A

mixture of solids and liquids

50
Q

filtrate

A

what you ore filtering

51
Q

decant

A

to carefully pour surface liquid

52
Q

creeping

A

loss of product when it exceeds filter paper

53
Q

hygroscopic

A

if something is hygroscopic it absorbs water from the atmosphere

54
Q

dessicant

A

salts that absorb moisture

—-> CaSO4

55
Q

Inorganic analysis:

A
  1. selective reagents

2. specific reagents

56
Q

selective reagents

A

targets a small group of ions.

ie. AgNO3

57
Q

specific reagents

A

target one ion

chelating structure using dimethylgloxine for Ni(+2)

58
Q

TGA

A

thermal gravimetric analysis