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INDUSTRIAL OILS AND DERIVATIVES
APPARATUS  1. Erlenmeyer flask—500 mL.
REAGENTS  1. Sodium hydroxide solution, 0.5 M—accurately standardized. See AOCS Specification H 12-52. 2. Ethyl alcohol—95%, SDA Formula 30 and 3A are permitted. Add a few drops of phenolphthalein indicator solution. Boil and neutralize with NaOH solution to a faint pink color just before using. 3. Phenolphthalein indicator solution—1.0% in 95% alcohol.
PROCEDURE  1. Weigh accurately 5 g of fatty acids into 500 mL Erlenmeyer flask and add 75–100 mL of hot neutral alcohol. Agitation and further heating may be necessary to bring the fatty acids into complete solution. 2. Add 0.5 mL of indicator and titrate immediately, while shaking, with 0.5 M NaOH to the first pink color which persists for 30 sec.
CALCULATIONS
Acid value, expressed as mg KOH per g of fatty acids = volume of titrant,mL M mass of test p ××5610
.o rtion,g  Where—M = molarity of accurately standardized sodium hydroxide solution.
faint
PRECISION At a confidence level of 95%:
Fatty Acids  Fatty Acids Distillates Tallow Coconut Material
Polymerized Residues Soybean Linseed Range of Values: 162–195 24–64 195–275T wo single determinations performed in 1 laboratory shall not differ from the mean value by more than: ± 0.8% ± 1.0% ± 1.2%Single determinations performed in different laboratories shall not differ from the mean value by more than: ± 1.3% ± 1.9% ± 1.4%

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