blending

Question 1

positive , negative and neutral mix

Answer 1

pos - spontaneous mix
eg misicbel liquids

negative mix - seperate unless work done eg imiscible liquids

neutral - work needed to mix, wont demix spontaneously
eg powders

Question 2

random mix what kind os SD vs non random mix

Answer 2

sd will be lower than if not random

Question 3

convective mixing

Answer 3

spatula in powder lift and deposit elsehwere

grp of adjacent particlrs from one location to another

Question 4

shear mixing

Answer 4

form slip planes in the powder

Question 5

diffusive mixing

Answer 5

body of powder lifted beyond its angle of repose
tumbling over each other
throw powder over powder
- individual unlike convective and shear involving groups of particles

Question 6

causes of demixing

Answer 6

diff in particle size - top small bottom big
diff in particle shape fibrious material gather
diff in particle density high density to the bottom

Question 7

the 5 types of segregation

Answer 7

1. percolation segregation
   - vibration or movement causign finer/ denser ones to percolate to the bottom
2. elutriation segregation
   in air stream lifitn gsmall partickes up
3. projection segregation
   - heavier particles projected furhter eg pouring or o conveyor
4. feed or heap segregation
   heavier particles roll further down the heap
   fine particles int eh middle
   free flowing also move further away
5. shear segregation
   when shearing , larger particles move faster and small move slower ,
   common in feede or , down a slope

Question 8

ordered mixing

Answer 8

• fine particles mixed with coarser particles , fines coat larger carrier and form relatively stable blend

3 forms of segregation this causes
1. ordered unit seg - due to size
2. displacement segregation - addition of another component eg mgst could displacce the adsorbed drug
3, saturation - limited active sites on carrier particles
prone to percolation

Question 9

geometric dilution

Answer 9

small amt mix with larger am tbut micing in 1-1 ratio with the excipient

Question 10

which blending equipment for large scale

Answer 10

IBC

Question 11

which blenders for small scale

Answer 11

v.y cone or double cone bin blenders

turbular - 3d movement

Question 12

mixing process

Answer 12

expand bed of solids
apply 3d shear forces to the powder bed
allow time to achieve random mix
maintain random mix , try not to cause demixing

Question 13

factors affecting mixing

Answer 13

• <1% actives makes it hard
• dec particle size
• narrow size distribution flow
• spherical round particles easier to mix

Question 14

sampling method

and devices

Answer 14

• map out area , ensure consistency
  eg 19 for 1000L ibc

scoop
thief keys - from middle
core sampling - 3-5 sampling points

Question 15

loading method

what about lubricants

Answer 15

layering
reduce number of blend revolutions
lubricants dont need layering, add to the top

Question 16

whats the end point

and how many

Answer 16

no of revolutions

top to bottom/radial 10-20 revs - complete by 6 revs

side to side 250 revs

Question 17

scale up

Answer 17

1-10

Question 18

fill level

Answer 18

60% optimum
80% longest
40% longer
20% posssible segregation

Question 19

solutions for no flow

Answer 19

external - frame or ibc
or internal vibrations - vibroflow

could end up consolidating
segregation , noise, ibc damage
weighing systems could be sensitive , product residue and dosing capability

Question 20

NIR - near infra-red analysis beenfits and for what

Answer 20

indicates ow well mixing is

no op contact - safety 
no sampling errors 
real time 
multi ingreident unifrmoity 
process understadning 
process finger printign for scale up 
right first time 
fast release - reduce cycle times 

NIR shld be stable with little variability

Question 21

key blending parameters

Answer 21

% fill 
loading method 
sampling 
no of revolutions 
formulation