# Bracket Standard Recovery Custom Field

hello,

I'm trying to figure out a way to calculate the bracket standard recovery using a custom field? i.e, the % difference of the bracket standard injections compared to the previous standard (bracket) injections.

• My username seems to have been wiped for some reason..

Cant you use a report for this? Label your standards as sequential eg S1 S2 S3...Sn etc, Then create peak tables which calculate the %RSD between labels S1 and S2 then S3 and S4 etc? You can use Data Filtering Conditions in the peak table of the report method to do this.
• our sop outlines the following equation to calculate percent bracket recovery:

% bracket recovery =[|A-B| x 2/ (A+B)] x 100

Where              A:        Mean area response of standard prior to the sample loop

B:         Mean area response of standard after the sample loop

Currently we use excel to calculate this , but  we are trying to get  away from the use of excel sheets (for data integrity purposes). I don't believe the report can do this , it would need to be a custom field from what I see

• Ok I see. How many injections of standard do you do? Ill presume 2. Label your standards as A and B. Make 2 peak, real calculated custom fields called A_Std_Subtraction and B_Std_Subtraction and code it as (A.1.(Area)+A.2.(Area))/2 and (B.1.(Area)+B.2.(Area))/2 and make sure to tick All or Nothing in custom field editor for both CFs. Then make a third peak, real cf called Recovery_Brkt_Stds and code it as ABS((((A_Std_Subtraction-B_StdSubtraction))*((2*(A_Std_Subtraction+B_Std_Subtraction))))*100)

Adding an ABS will allow for any negative values. This should work if you label all your standards as A and B so A----samples----B then another set of A......samples....B etc. Because of all or nothing, your % bracket std recovery should only generate a result for all the B standards, where all arguments are present. So at each B injection, your value for Recovery_Brkt_Stds will calculate using the current B and the previous A injections, then this repeats again for the next set. But this assumes you are using a Sliding No Overlap method of standards injections where you quantitate your samples off A and B, clear calibration then start again with a new A and B. If not this wont work. Also, there is every chance there is an easier way to do this, im just going by what I see and I haven't access to a test project, so good luck.