how to calculate the recovery of a spiked sample substracting the amount in the non-spiked sample

Here is one way, it can be modified as needed.

For the recovery I am using the formula:

%R = ((Spiked sample result - Unspiked sample result) x 100%) / Known spike added concentration

In the Project, I chose to make a Sample Custom Field to link the Sample and the Spike, type in the name of the Sample Name to link with the Spiked Sample, if the sample is not to be linked with a Spike, leave it blank.  Using a Compound Custom Field for the Spike Concentration.  If its a fixed concentration, this can be put in the formula below instead of using the customer field.

Create a Custom Calculation File.  Used the Formula beow (change the names in the formula if needed to match the Sample and Compound Custom Parameters that were created in the Project):

IF(CurrentSample.GetCustomField("SpikeSample")<>””, (Compound_Amount - CurrentSequence.AllInjectionsBySampleName(CurrentSample.GetCustomField("SpikeSample")).First().AllPeaksAndGroupsByName(Compound_Name).first().Compound_Amount)/ CurrentPeakOrGroup .GetCustomField(“SpikeConc”)*100, "")

In the Sequence or in the Injection List fill in the Sample name in the SpikeSample column to link the Spike to the Sample it corresponds to.  Type in the Known Spike concentration in the Compounds Custom Field.

Thank you sgamba for your help. I have done some little modification to your equation in order to make it useful for use.

However, there is one parameter that I do not know how to change. We “correct” the compound amount  with the smple weight and some other constants in a CC file call “p_p_SR”. I can change it in the first part of the equation, but it gives an error when I change it on the second part.

I will be very pleased if you could help me fixing that last issue.

I really appreciate your help.

Best regards

Oihana

Oihana,

Try first.GetDoubleCC("p_p_SR")) at the end of that expression in place of first()."p_p_SR") assuming your p_p_SR CC is a double type. 

Marty