E1 L2 - Emulsion

Question 1

Emulsion

Answer 1

System of two immiscible liquids in which one is dispersed as droplets (eg. water phase + oil phase)
-(in pharm: two phases are generally water and oil)

Question 2

Emulsion phases

Answer 2

Dispersed phase
Continuous phase (=external phase)
Determines organoleptic properties (taste, smell, feel) of the emulsion

Question 3

Applications of emulsion: Oral

Answer 3

O/W: mask the taste of an oil (eg. mineral oil as laxative)
O/W: Enhance absorption of an oil (Vitamin A and D, cod liver oil)

Question 4

O/W

Answer 4

Dispersed: Oil
Continuous: Water

Question 5

W/O

Answer 5

Dispersed: Water
Continuous: Oil

Question 6

Applications of emulsion: External

Answer 6

O/W: Water-washable; vanishing cream
W/O: For cleansing skin (cold cream)

Question 7

Applications of emulsion: IV

Answer 7

O/W
For parenteral nutrition
100mL of 20% lipid emulsion provides 200 Kcal, while 100mL of 5% dextrose only provides 20 kCal
Smallest capillaries are 5mcg. It is CRITICAL that the droplet size is less than 1 mcg to avoid embolisms

Question 8

Interfacial phenomena

Answer 8

Molecules surrounded by attractions equally
At boundary between phases - molecules acted upon unequally by different forces of attraction
-Water: H bond
Mineral oil: London Dispersion forces
-Molecules at interface experience interaction forces different
-in liquids, this imbalance leads to spontaneous movement of molecules from the interface into the bulk phase. This leaves fewer molecules per unit area at the interface

Question 9

Interfacial (surface) tension reversal:

Answer 9

Any attempt to reverse the spontaneous movement of molecules at the interface causes the interface to resist expansion and behave as though it is under a tension everywhere in a tangential direction

Question 10

Force of tension per unit length

Answer 10

Interfacial tension

Question 11

Interfacial tension - liquid - liquid interface

Answer 11

Oleic acid - water 15.6 dynes/cm

Question 12

Interfacial tension - liquid - air interface

Answer 12

Water - air = 72.8 dynes/cm
Oleic acid - air = 32.5 dynes/cm

Question 13

The stronger the intermolecular force in a bulk phase…

Answer 13

The higher the interfacial tension

Question 14

The greater the tendency to interact…

Answer 14

The less the interfacial tension

Question 15

The highest temperature

Answer 15

The lower interfacial tension (Intermolecular forces are reduced at high temps)