Particle Size Analysis

Question 1

Challenges

Answer 1

• HETEROGENEOUS powder particle size - RANGE
• IRREGULAR particle shapes
• 2D

Question 2

Solutions

Answer 2

Equivalent sphere diameter
Statistics
Analytical techniques

Question 3

Particle shape considers

Answer 3

Convexity, aspect ratio, circularity, solidity

Question 4

Particle size ANALYTICAL TECHNIQUES

Answer 4

Sieving
sedimentation
microscopy
image analysis
laser diffraction
dynamic light scattering
electrozone sensing

Question 5

LASER DIFFRACTION:

particle size range

Answer 5

0.01-3500ym

Question 6

LASER DIFFRACTION:

mechanism

Answer 6

Particles passing through the laser beam scatter light.

ANGLE OF LIGHT SCATTER is measured by photodetectors around sample chamber
- measures LIGHT INTENSITY

Question 7

LASER DIFFRACTION:

smaller particles have a ____ scatter angle

Answer 7

WIDER

Question 8

LASER DIFFRACTION:

advantages

Answer 8

RAPID (mins)
minimal sample prep
NO CALIBRATION

Question 9

DYNAMIC LIGHT SCATTERING:

particle size range

Answer 9

0.3nm-10ym

Question 10

DYNAMIC LIGHT SCATTERING:

mechanism

Answer 10

(same as laser diffraction)
BUT
Photodetectors measure FLUCTUATIONS in scatter.

Scatter due to BROWNIAN MOTION

Question 11

Compare LD & DL:

Answer 11

LD uses wet & dry samples (DL: wet only)
LD: broader particle size range
LD measures ANGLE OF LIGHT SCATTER
DL measures FLUCTUATIONS of light scatter

Question 12

NORMAL DISTRIBUTION CURVE:
mean
median
mode

Answer 12

mean=median=mode

Question 13

NORMAL DISTRIBUTION CURVE:

shows

Answer 13

UNIFORMITY of particle size

Question 14

BIMODAL DISTRIBUTION:

relate modes & peaks

Answer 14

1 peak = 1 mode

2 peaks = 2 modes

Question 15

BIMODAL DISTRIBUTION:

shows

Answer 15

2 or more distinct populations in powder

Question 16

NEGATIVE SKEW:
mean
median
mode

Answer 16

mean

Question 17

NEGATIVE SKEW:

shows

Answer 17

MORE LARGER PARTICLES

Question 18

NEGATIVE SKEW:

peak lies on ___ side

Answer 18

RIGHT

Question 19

POSITIVE SKEW:
mean
median
mode

Answer 19

mean>median>mode

Question 20

POSITIVE SKEW:

shows

Answer 20

MORE SMALLER particles

Question 21

POSITIVE SKEW:

peak lies to ____ side

Answer 21

LEFT

closest to y axis

Question 22

D values:

calculate

Answer 22

SPAN

IQCS

Question 23

SPAN

equation

Answer 23

(D90-D10)/D50

Question 24

SPAN shows

Answer 24

width of particle size distribution

Question 25

IQCS<0

Answer 25

NEGATIVE SKEW

Question 26

IQCS>0

Answer 26

POSITIVE SKEW

Question 27

IQCS=0

Answer 27

NORMAL DISTRIBUTION

Question 28

IQCS values lie between range .......

Answer 28

-1 and +!

Question 29

IQCS shows

Answer 29

Interquartile coefficient of skewness

Question 30

POLYDISPERSITY INDEX: shows

Answer 30

uniformity of particle size

Question 31

POLYDISPERSITY INDEX: | assumes

Answer 31

NORMAL DISTRIBUTION

Question 32

POLYDISPERSITY INDEX: | equation

Answer 32

SD | mean particle size

Question 33

POLYDISPERSITY INDEX: | MONODISPERSE

Answer 33

narrow dist, uniform particle size

Question 34

POLYDISPERSITY INDEX: | POLYDISPERSE

Answer 34

broad dist | variable particle size

Question 35

DYNAMIC LIGHT SCATTERING: | which equation relates?

Answer 35

Stokes-Einstein Equation