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Peak area units in MassLynx 4.1 / Quattro Ultima Pt
Posted: Wed Jun 25, 2014 3:16 pm
by bunnahabhain
Hi everyone
I was just asked by our quality assurance what unit MassLynx uses for the peak areas. I have looked around in the help files and manuals but didn't find anything. I would think of counts*min or mV*min, but I really don't know. Anybody else?
Regards,
Jörg
Re: Peak area units in MassLynx 4.1 / Quattro Ultima Pt
Posted: Thu Jun 26, 2014 3:50 pm
by mhr311
Its actually bit-minutes (therefore 60A being bit seconds). Useful in calculating sensitivity(S) based on: S(columb/ug)=60A/1.07x10(9) x 1.0x10(-6)/Mult.Gain.
1.07x10(9) is the maximum ADC response and 1.0x10(-6) is the ion beam current in amps to produce the maximum response. A is peak area.
Re: Peak area units in MassLynx 4.1 / Quattro Ultima Pt
Posted: Fri Jun 27, 2014 3:07 pm
by bunnahabhain
I'm not sure I understand that...
So the actual measurement value is a current in µA (microampere)? So the peak area is µA*min, correct?
Thank you for the information!
Jörg
Re: Peak area units in MassLynx 4.1 / Quattro Ultima Pt
Posted: Fri Jun 27, 2014 7:24 pm
by mhr311
In the sense that for some number 'x' amp you have an ADC conversion of the bit slice to some number 'y' which has to account for some given multiplier gain factor. Consequently, the area under the peak has the units of bit(s) per unit time, in this case minutes. In order to calculate the actual mv (or microamp) for an individual peak, you'd need both the multiplier gain (hard to calculate on a quad with no faraday cup)and the response factor used for the experiment.