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Pre-lab 6

Pre-lab 6. Items Covered In This Lab. 1. Problems: Dilution and Concentration 2. Prescription: Liquid paraffin oil emulsion. DILUTION AND CONCENTRATOIN (P: 40 ). Add 100 ml water. 1 gm NaCl in 200 ml solution . 1 gm NaCl in 100 ml solution . 0.5 %. 1%.

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Pre-lab 6

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  1. Pre-lab 6

  2. Items Covered In This Lab 1. Problems: Dilution and Concentration 2. Prescription: Liquid paraffin oil emulsion

  3. DILUTION AND CONCENTRATOIN (P: 40) Add 100 ml water 1 gm NaCl in 200 ml solution 1 gm NaCl in 100 ml solution 0.5 % 1% Amount before dilution = Amount after dilution Q 1 C 1 = Q 2 C 2 N.B. Q 1 & Q 2 must have the same units C1 & C2 must have the same units

  4. DILUTION AND CONCENTRATOIN Example:Aluminium acetate solution contains 5% of aluminium acetate. When 100 ml are diluted to a liter, what will be the diluted solution ?Answer:Q 1 = 100 ml C 1 = 5%, Q 2 = 1 liter = 1000 ml C 2 = ??Q1 C1 = Q2 C2 100 ml X 5% = 1000 ml X C2C2 = 0.5%

  5. Dilution of Alcohols and acids • Since there is a volume contractionwhen alcohol & • water are mixed together • we can not calculate the volume of water needed to dilute alcohol to a desired v/v strength • Strength of official concentrated acids % w/w • Strength of official diluted acids  % w/v N.B. % w/ v = % w/w X specific gravity

  6. Example: How much water should be mixed with 5000 ml of 85% (v/v) alcohol to make 50% (v/v) alcohol ? Answer: Q 1 = 5000 ml C 1 = 85% v/v Q 2 = ? C 2 = 50% v/v Q1 C1 = Q2 C2 5000 ml X 85% = Q2 X 50 %Q2= 8500 ml Therefore ; use 5000 ml of 85% (v/v) alcohol & enoughwaterto make 8500 ml

  7. EMULSIONS (P:88) • Two immiscible liquids, e.g. water and oil, one of which is • dispersed as small globules (internal phase) in the other (external • phase) by the aid of emulsifying agent (e.g. gum acacia). Oil (internal phase) Emulsifying agent H2O (external phase) Water

  8. To prepare acacia emulsion, A Primary Emulsion must be made first With fixed ratios of Oil : Water : Gum

  9. Possible causes of phase inversion Use of a mortar that is too small or has a very curved base. Use of a pestle with rounded head that does not provide the broad flat surface necessary for a good shearing effect. Inaccurate measure of oil or water. Contamination of oil with water, or vice versa, due for example to “measuring the oil or water in wet or oil measure respectively. Use of wet mortar. Excessive mixing of the oil and gum (coating gum particles with oil → water cannot penetrate) 7. Diluting the primary emulsion before it has formed properly. 8. Poor quality of acacia.

  10. Special problems in emulsion compounding • a- Presence of inorganic salts • → ppt the emulsifying agent • Dissolve in part of vehicle and diluted before addition to the diluted emulsion in small amounts with constant stirring. • b- Presence of tincture and other alcoholic solutions • → ppt the emulsifying agent • Add drop wise to the diluted emulsion with constant stirring.

  11. Special problems in emulsion compounding • c- Presence of substances insoluble in oil or water • Must be finely powdered and gradually triturated with diluted emulsion or mixed with acacia before making a primary emulsion (if not use micro fine grade of powder • e.g. phenol- phthalein liquid paraffin B.P.C) • d- Small proportion of oil • Acacia emulsions containing < 20% of oily liquid cream readily • To prevent this, a bland fixed oil (e.g. castor oil) should be added to ↑ total weight to ≈ 20%. • Calciferol and Bromoform are examples of medicaments that require such dilutions

  12. Liquid Paraffin emulsion (p.95) Rx Liquid Paraffin ℥ss 15 ml Gum Acacia Q.S. Spirit Mentha min xv (15 x 0.06 = 0.9 ml) Water to ℥ii 60 ml Fiat: Haustus Sig.: Statin Shake The Bottle The Draught To be taken at once.

  13. 10 ml • 15 ml • 5 gm • Liquid Paraffin is a mineral oil • Prepared using the dry gum method Uses • It softens fecal contents by retarding water reabsorption, so it is useful in chronic constipation.

  14. 10 ml Water on the otherside Dry gum Method • Trituration must be: • From the wrist. • In one direction. • In all parts of the morter. • Continueous. • Very Fast. 15 ml Oil on oneside In a dry mortar; add gum & grind with pestle Place gum in a line in the center Triturate with whipping motion until primary emulsion is formed (white , thick ,cracking sound) Continue triturating for 2 min. (stabilization)

  15. 10ml Water Dpwise& triturate 10ml Water portion-wise & triturate Dry gum Method Wipe with a tissue adjust volume to 60 ml with water Wipe with a tissue Primary Emulsion

  16. Thank you

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