# Assay/ concentration

Member
edited August 8
Are assay and concentration same in effect while formulating?

While formulating detergents or any other product, if commercially available raw material is at a lower concentration than needed, can we use it in larger quantity.

For eg., SLES is needed at 69% assay . I am getting it in 28% concentration. Can I use the 28% SLES in increased ratio?

• Administrator, Professional Chemist
If you need 69% SLES in your formula and the raw material is supplied as 28% you won't be able to do it. You would have to evaporate off some of the water to increase the concentration of SLES.

For every 100 grams of a 28% solution you put in, you are only putting in 28 grams of SLES.
• Member
The lower the assay the more you need to supply the ingredient you are after.

The maths is simple: What you want, divided by what you have, multiplied by 100.

So, 69 %/28% x 100 = 246.4% which clearly will not work.
• Member
Perry said:
If you need 69% SLES in your formula and the raw material is supplied as 28% you won't be able to do it. You would have to evaporate off some of the water to increase the concentration of SLES.

For every 100 grams of a 28% solution you put in, you are only putting in 28 grams of SLES.

Thanks Perry.

I understand that evaporating is a sure shot solution.

My formula states 10 % of 69% SLES (it is a water based formula)

So, 10*69/28 =24.6 % _ That is, 28% SLES in the amount 24.6 %

Here, I am adding additional water with the 28% SLES so I shall deduct water in the formula proportionately.

Can this be done?

• Administrator, Professional Chemist
If you are adding 10% of a 69% SLES solution,  that means you are adding 6.9 grams in 100 grams.  So, to get 6.9 you would need 24.6% of the 28% solution. Then subtract the excess volume from the water.

Yes, that would work.
• Member
Thanks again Perry .
• Member
Herbnerd said:
The lower the assay the more you need to supply the ingredient you are after.

The maths is simple: What you want, divided by what you have, multiplied by 100.

So, 69 %/28% x 100 = 246.4% which clearly will not work.
Thanks Herbnerd.