[fedaai]

I'm doing some validation work on Atomic Absorption, but little bit confused about the calculation formula of using external standards..
I wonder if you can support me?

Our work is basically the following:
1- Dissolving powder (contains both metallic & organic compounds) sample (500 mg) in Acid/organic solvent approx. 75ml acid & 25ml organic solvent
2- separate the aqueous layer in 100mL flask
3- run the samples in the FAA. .

he formula I have is:

A) Content of metal in the sample = [conc FAA reading (ppm) x V.Flask (mL) ] / sample weight (g)

this formula is not working correctly with me, but I have also seen another formula in some books with slight difference & it works perfectly..

B) Content of metal in the sample = [conc FAA reading (ppm) x V.Flask (mL) ] / sample weight (g) x 100

MY QUESTION: if the second formula is the right one, from where (100) in the formula ?

[Borek]

Isn't it just a conversion factor to %?

[fedaai]

Hi Borek!

I'm little bit confused, what should be the correct calculation in my case?

example: (Al concentration)
I've weighted 500mg of sample (contains both organic & inorganic compounds) into  250ml conical flask . adding about 75ml acid & 25ml solvent & then heating. after heating, I've separated the aqueous layer into 100mL flask & making it up with acid.

this sample is then analyzed & I get FAA reading  of (Al) in ppm.

what should be the correct calculation?

[Borek]

What units do you want your answer to be expressed in?

100 looks like some kind of a conversion factor.