AOCS Te 1a-64 - Acid Value (2017) PDF [PDF]

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INDUSTRIAL OilS AND DERIVATIVES

Official Method Te

•

1a-64

Reapproved 201

Acid Value of Commercial Fatty Acids

APPARATUS

1. Erlenmeyer flask-500 mL.

REAGENTS 1. Sodium hydroxide solution, 0.5 M-accurately standardized. See AOeS Specification H 12-52. 2. Ethyl alcohol-95%, SDA Formula 30 and 3A are permitted. Add a few drops of phenolphthalein indicator solu­ tion. Boil and neutralize with NaOH solution to a faint pink color just before using. 3. Phenolphthalein indicator solution-l.O% in 95% alcohol. ~

:§ ::is

PROCEDURE

5­ -s"

'0

·s'§=

•

1. Weigh accurately 5 g oHatty 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.

!L

"=

tl

.~

CALCULATIONS

:;

0

-s

Acid value, expressed as mg KOH per g of fatty acids

.~

~

"e

volume of titrant, mL x M

x 56.10

mass of test portion, g

Where­

!i

.E

M

l5

molarity of accurately standardized sodium hydroxide solution .

5

..e

'"c.

PRECISION

-----------------------------------------------

.5

At a confidence level of 95%­

11 :::

.~

Fatty Acids Polymerized

Distillates Residues

Fatty Acids

Tallow, Coconut,

Soybean, linseed

Range of Values:

162-195

24-64

195-275

Two 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%

:;= l5

8 1"

Q.

~

"

..Q

~

E

."

~

"E ~

~

""0

5c..

•

0

Z

1 ~

t

·c

':;! Copyright © 2017 by the American Oil Chemists' Society Refer to the AOCS Laboratoty Safety chapter when using this Method.

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Copyrighr © 2017 by rhe AOCS Refer to the AOes Laborarory Safety chapter when using rhis Method.