# Calculation of Amount, ISTD

Hello,

I have a Question concerning the Calculation from Chemstation.

We have a run of a trace analysis of a solvent.

Our calibration table got 2 components.

Solvent 1 amount 79. mg/L   Area 210

Solvent 2 amount 1.0 mg/L  Area 397  ISTD

Std Run       Run1                                                                                                           Run2

Solvent 1 amount 79.0 mg/L Area 213  amount area 3,7 e-1  amt Area Ratio 146.2     Area 210  amt area 3,75 e-1 amt Area Ratio 149.2

Solvent 2 amount 1.0 mg/L Area 394     amount area 2,5 e-3 amt Area Ratio 1.0         Area 397  amt area 2,51 e-3 amt Area Ratio  1.0

SST Run

Solvent 1 amount 31,85 mg/L Area 149

Solvent 2 amount 1.0 mg/L Area 398

So the result is 31,85 mg/L ( The Results are from the Chemstation )

We want to reproduce the result on the Open Labs 2.1

Solvent 1 amount 79,0 mg/L Area 290,7

Solvent 2 amount 1.0 mg/L  Area 532,421

Calculation of the calculation factor is Area Solvent 2 divide Area Solvent 1. Which is here 1,8 and above 1.9 so the relativity is the same

So we take this factor multiply it by 50 then 2 then 0.79.

This value we take to calculate  its around 145 = F

The calculation after is Solven1 amount =( ( area solvent 1/ area solvent 2 ) * F * 50 * 2 ) / 10000

No matter what I do I just don't get the 32 mg.. I assume that there is some Factor that the Chemstation calculates the result with.

So the 2 main questions are.

Is there a chance to review the calculation from the chemstation which is bound in the method ?

2nd how the Chemstation calculate the Value of 32 mg/L ?

If you need more Details let me know.

• I found the Solution,

The Solution was very simple.

Just add as ISTD Amount 1. Then under "Level1" I have to add 79,0  ( Density of the Solvent 1 ) * Dilution Factor.

I was very happy that it was so simple.