Custom field with internal standard

smaroulas

Hello, i would like to create a custom field, which i inject 5 standards. Each standard contains 5 peaks and one peak internal standard (total 6 peaks). Then i inject the second standard for % recovery. The calculation for each peak:
(ARstd2/ARstd1)*(Wstd1/Wstd2)*100
ARstd2=Area(solvent)/Area(internal std) (of second standard)
ARstd1=Area(solvent)/Area(internal std) (of first standard)
Wstd1= weight of first standard for each solvent
Wstd2= weight of second standard for each solvent

How can i make it for each solvent. Do you have any idea?

Empower2019

For solvent I presume you mean peak? And in your formula, for the Area(Internal standard) of first standard is that the average area of internal standard over the 5 injections?

smaroulas

The solvents are 5. Each solvent is an individual peak in one mixture with internal standard inside (another peak). So 6 peaks. 5 injections of a mixture of 5 peaks and one peak of internal STD. The average of each Areapeak/ Areainternal std

Empower2019

Three custom fields will do this. Label your first standard of 5 injections as S1, the second one as S2 and populate CCalRef1 of your processing method with the Internal Standard peak. Put the standard weight for first standard of each solvent peak into CConst1 of processing method and standard weight for second standard for each solvent peak into CConst2 of processing method (so if your standard weight was 101.998mg put 101.998 into CConst1/2).

Percent_Recovery_A

S2.%.(Area)/S2.%.(CCalRef1[Area])

Percent_Recovery_B

S1.%..AVE(Area)/S1.%..AVE(CCalRef1[Area])

Total_Percent_Recovery

(Percent_Recovery_A/Percent_Recovery_B)*(CConst1/CConst2)*100.

Make sure the function "Summarize Custom Fields" is inserted as the last line of the sample set and the "Processing" Column is set to Normal for that row. Process the sample set to generate a result set, Job done. % Recovery for each of the 5 solvent peaks obtained. Worked perfectly for me when I tested it.

Empower2019

Actually, I just realized since you are using Internal Standard, then the field "Response" automatically calculates the Area of each peak over the area of the peak designated as Internal Standard for each sample so your calculation can all be done in one custom field:

(S2.%.(Response)/S1.%..AVE(Response))*(CConst1/CConst2)*100