The correct formula is: (V-b)*N*56.1/W

Please refer: http://www.eplantscience.com/index/plant_protocols/lipids/Estimation_of_free_fatty_acids.php

The formula is correct, FFA% (OLEIC) you will be getting as the answer. 

 FFA%=(v-b) X N X28.2/w, v is the volume of the titrant, b is the blank volume, N IS THE NORMALITY USUALLY .25 N,

v is the volume of the titrant, b is the blank volume, N IS THE NORMALITY USUALLY .25 N,

b is the blank volume, (titration without mixing with oil)

N IS THE NORMALITY USUALLY .25 N,

28.2 is the molecular weight of oleic acid(282) divided by 10,

w is the weight of the oil used.(7.5gm)

(V-b)*N*56.1/W

with this equation, we will get the Acid no in mg/KOH

https://corn.org/wp-content/uploads/2009/12/FREEF.01.pdf

its rather a question. Why divide by 10

Bineesh Mathew why divided by 10

Nawab ji , i dont know ,i didnt invented the equation, i just shared what i know.

Oleic acid (282.47)

KOH

Potassium hydroxide (56.1)

56.1 gm = 282.47 gm

1 mole of KOH = I mole of Oleic acid

When we use 0.1 N KOH for neutralization then we will divide by 10, if we use 1 N KOH then there will no need to divide by 10.

Moreover, if we use 0.25 N KOH then it will be divided by 4.

Farhan Saab, Tit-ration is against 1N, the factor should be 282, why it is 28.2

FFA%=(v-b) X N X28.2/w

Dear Sir,

Try using a simple method called "Isopropyl Alchol Method".

You simply add 1ml of oil with 10ml of IP Alcohol and few drops of phenolphthalein indicator. Titrate this mixture against 0.1N KOH until pale pink color last longing for 10 sec appears. Note down that as your end point and That's your acid value.

Its very simple and more reliable. This method helps in giving you your oil's acid value directly and FFA through a simple relation.

FFA % = Acid Value/2

In case of NaOH, then FFA % = Acid Value/1.42

Good luck with it

The correct formula for FFA% (OLEIC ACiD) is

FFA%=(v-b) X N X28.2/W,

v is the volume of the titrant, b is the blank volume, N IS THE NORMALITY USUALLY 0.1 N, and W is the weight of sample.

Dr Nawab Sher Anita Goyal According to the definition[1] of FFA%, It is the mass percentage of Oliec acid [mg] in Oil [g]. So, If we find the mass of Oleic acid (from molar balance) by (V -b) X N X 282 (as detailed by Bineesh C Mathew ), it will be in gram. For this amount to be in mg, we need to divide this factor by 1000. And with the 100 of percentage multiplied, in the final expression we left with FFA% = ((V -b) X N X 282/10)/W

[1] The Lipid Handbook with CD-ROM By Frank D. Gunstone, John L. Harwood, Albert J. Dijkstra (page 423)

https://books.google.com.pk/books?id=INZa6WmqDA8C&lpg=PP6&dq=The%20Lipid%20Handbook%20with%20CD-ROM&pg=PP6#v=onepage&q=The%20Lipid%20Handbook%20with%20CD-ROM&f=false

Justification for the equation (also available in FSSAI Manual)

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Free fatty acid[% (as oleic caid )]= (T*N*282*100]/(W*1000) (This actual Equation A)

= (T*N*28.2*]/(W)

Where T=Titrate value (ml)

N= Normality of KOH

282= molecular weight of oleic acid

W=Weight of Sample(g):Fat

Hope, it will helpful to interested researcher. If you want to know Equation A, Please message me.

Thank you, Good Luck

yes, this formula is correct

What method is this called? I'm getting all kinds of answers from the web.

Some say ASTM 994 some say otherwise.

Just need some clarification. Thanks

Sir, this formula assumes that the main constituent of your fatty acid is is Oleic Acid which has the molecular mass of 282.4 g/mole, however, usually your fatty acid is a mixture of different acids, and AOCS have different formulas for different basis of the fatty acids.

What you might want to do is to have a rough estimated or analytical data for what is called fatty acid profile, which gives the fraction of each one of the acids that constitute your fatty acid.

then you can calculate the average molecular weight based on the fractions of each constituent and its own molecular weight and divide it by 10 and plug it instead of 28.24 that you have in your formula.

most of the times, it is hard to get the fatty acid profile, then you might estimate that based on the main constituent of the fatty acid, as AOCS do, for example, if your fatty acid is palmitic based, you would choose 25.6 instead, and so on. those estimations might give you very unlikely acidity and far from reality in comparison with precise analytical method.

Try using a simple method called "Isopropyl Alchol Method". You simply add 1ml of oil with 10ml of IP Alcohol and few drops of phenolphthalein indicator. Titrate this mixture against 0.1N NaOH until pale pink color last longing for 10 sec appears. Note down that as your end point and That's your acid value.

This formula name please!

Take isopropyl 125 ml + oil sample 1g + phenolphthalein 3 drops into a titration flask.

Fill the burret with 0.1M KOH sample.

Conduct the titration untill the solution in the flask change the color from colorless to pale pink. Record the consumed volume as V1.

Repeat the same proprocedure for blank sample without adding 1g of oil into the flask and record the consumed volume as V2.

Then, apply the obtained value below equation to get the Acid value ( AV)

AV = 0.1* 56.1 * (V1-V2)

Thereafter, apply the value come from above equation to get the FFA% as demostrated in below,

FFA% = (AV/2)

Please refer this article,

https://www.researchgate.net/publication/358752193_Production_of_Biodiesel_Using_Acetone_as_a_Co-_Solvent?_sg%5B1%5D=

Exactly Viraj Miyuranga you have mentioned the best way of calculating.

Thats how i solved this,

I have searched ISO limit values of soaps and detergents, but I could not. anyone who can help me, please?