Great video, Peter. I wonder why you calculated the concentration value instead of using the value of Compound_CalibAmount, since this would take the specified amount from the calibration table directly? Would that achieve the same thing instead of the calculation back to the multiplier value that you added to the calibration table? I guess you would need to set the sample type of these injections to Calibration for this to work.
Hi Andy, thanks for viewing and you are absolutely right. If the standard you are running for LOD calculation is the same as the one in the calibration table you can definitely use compound_calibamount (with sample type as calibration of course). However I was trying to be a bit generic in case the standard being run for LOD calculation is at different concentration (which is usually the case I think, for example calibration at 10 ppm but running 1 ppm standard to verify LOD). Would that make sense to you ?
Hello! Your videos are a blessing! Thank you for taking the time to teach. I have one question. How does one calculate threshold? We’re using an Agilent GCMS with chemstation. Trying to learn more before we start running EPA 524.2 Our baseline right now is 10000 abundance and wish to decrease this to see our low concentration standard of .5ppb Our threshold is set at 100 now. How is threshold determined?
Hello, it seems like you are referring to the threshold in MSD Chemstation’s integration. If so, there is no formula to correlate its value to concentration as far as I know. You would probably want to run your 0.5 ppb first then slowly adjust the threshold until your target peaks start integrated.
Check out other approaches for calculating limit of detection at ruclips.net/p/PLaYUUU64uRTlyuU-R1b46QeKbS3GNvwMu
Thanks for this helpful video
You are welcome. Glad you find it helpful.
Thanks for the videos Peter! Hope you 're well!
Thanks for viewing, have a good day
Great video, Peter. I wonder why you calculated the concentration value instead of using the value of Compound_CalibAmount, since this would take the specified amount from the calibration table directly? Would that achieve the same thing instead of the calculation back to the multiplier value that you added to the calibration table? I guess you would need to set the sample type of these injections to Calibration for this to work.
Hi Andy, thanks for viewing and you are absolutely right. If the standard you are running for LOD calculation is the same as the one in the calibration table you can definitely use compound_calibamount (with sample type as calibration of course). However I was trying to be a bit generic in case the standard being run for LOD calculation is at different concentration (which is usually the case I think, for example calibration at 10 ppm but running 1 ppm standard to verify LOD). Would that make sense to you ?
Hello! Your videos are a blessing! Thank you for taking the time to teach.
I have one question. How does one calculate threshold? We’re using an Agilent GCMS with chemstation. Trying to learn more before we start running EPA 524.2
Our baseline right now is 10000 abundance and wish to decrease this to see our low concentration standard of .5ppb
Our threshold is set at 100 now.
How is threshold determined?
Hello, it seems like you are referring to the threshold in MSD Chemstation’s integration. If so, there is no formula to correlate its value to concentration as far as I know. You would probably want to run your 0.5 ppb first then slowly adjust the threshold until your target peaks start integrated.
Thank you Sir!