Calculating peak resolution for GC/MS
Posted: Thu Apr 15, 2010 3:55 pm
I was wondering if someone could help me. I came upon the chromatography forum this morning for the first time. I am having a problem calculating resolution of two peaks run on the GC/MS. The Resolution calculation I have is:
Rs = 2*(Rt2-Rt1)/(W1+W2)
I think this definition uses *baseline* resolution:
I was told that if my separation is greater than 1.5 than that’s good resolution. However I don’t come up with anything close to that when I plug in the numbers using the actual retention time. Should my retention time be measured in mm instead of minutes? I'm assuming the measurement should begin at zero and go to the apex of the peak?
I saw this formula posted: R = Rtb – Rta/ 0.5 (pWa + pWb)
I read this morning that this formula was to be used when calculating width at half height? But then I thought it was then stated that if the peak isn’t a perfect Gaussian peak you would substitute in 1.7 instead of 0.5?
If the peak isn’t a perfectly Gaussian, then why wouldn’t you use the formula taking the peak width at the base instead of using the 1.7 at half height?
Later I saw this formula: N = 16 (tR/Wb) ^2 (does this mean the power of 2?)
Why would I use 16 vs. 5.54 or some other number?
I have problem with tailing on my first peak. I’m unsure of where to take the measurement from. Someone told me to take it 10% from the peak base
If you could help me I would be most grateful.
Sincerely,
Tammi Jacobs Shulman
Rs = 2*(Rt2-Rt1)/(W1+W2)
I think this definition uses *baseline* resolution:
I was told that if my separation is greater than 1.5 than that’s good resolution. However I don’t come up with anything close to that when I plug in the numbers using the actual retention time. Should my retention time be measured in mm instead of minutes? I'm assuming the measurement should begin at zero and go to the apex of the peak?
I saw this formula posted: R = Rtb – Rta/ 0.5 (pWa + pWb)
I read this morning that this formula was to be used when calculating width at half height? But then I thought it was then stated that if the peak isn’t a perfect Gaussian peak you would substitute in 1.7 instead of 0.5?
If the peak isn’t a perfectly Gaussian, then why wouldn’t you use the formula taking the peak width at the base instead of using the 1.7 at half height?
Later I saw this formula: N = 16 (tR/Wb) ^2 (does this mean the power of 2?)
Why would I use 16 vs. 5.54 or some other number?
I have problem with tailing on my first peak. I’m unsure of where to take the measurement from. Someone told me to take it 10% from the peak base
If you could help me I would be most grateful.
Sincerely,
Tammi Jacobs Shulman