[lovevictory]

  so i have a graph that looks like this

http://i31.tinypic.com/141l01l.jpg

and as the picture says, is that a peak? even though the line does not go down all the way ? and the little curve jutting in between what seems to be a peak... is that separating two peaks? i dont understand what to make of those "incomplete peaks" ... if they are not peaks, what causes them? and if they are, how can i find the area under them?  thanks..


EDIT-

for the area, i heard i can form some sort of triangular diagram under these incompletely resolved peaks and find the area? but im not quite sure of the method, does anybody know the formula for this?

[Yggdrasil]

They are overlapping peak.  Since they are overlapping it is difficult to estimate the area underneath them.

[Arkcon]

Any or all of them could be peaks, I count possibly 4 peaks -- the second one you ask about may be a doublet, two peaks run together or one peak split because of some problem.  This is not a good chromatogram to work with, even  worse for manual integration.  Do your best manual integration, or redo the run, if you can.

[lovevictory]

^^ thanks both of you for confirming about the peaks. it is not possible for me to do another run because i only had limited time with the GC and unfortunately im stuck with these results ...

for the area, i heard i can form some sort of triangular diagram under these incompletely resolved peaks and find the area? but im not quite sure of the method, does anybody know the formula for this?

[Arkcon]

OK, lets start with what we know.  First off, how many peaks did you expect?  Were there supposed to be 3, or 4, or how many components in your sample?  Can you find out what the last person's or the next person's run looked like, and see any similarity?  Did someone else run the same sample, things like that.  See what the instructors say they can help you with.  As I was taught in my first analytical chemistry course, no one drops a sample on your desk and says, "You the chemist, you figure out what it is."  We generally know at least a little bit about what we're looking for.  Run that by the instructors and see what they say.

I've only run a GC once, for the above mentioned Analytical Chemistry class.  At that time, the GC's integrator failed, for reasons the T.A. couldn't explain, or fix in a reasonable time frame.  So I just took the plots, and was told to use height to determine relative concentrations between standards and unknowns.  Many people will react with a knee-jerk response against height quantification, but it can be necessary for bad peaks shapes, or adequate for some purposes.  Again you have to see what the instructor says.

Now, the triangle method of determining peak over-lap is a method of determining the overlap area between two already integrated peaks.  If you need to know the complete area under these poorly separated peaks, and the badly fronting final peak, a triangle isn't going to integrate it for you.  An old trick that was related, but not taught, to me was: making copies of the curve, and carefully cut out the curves.  Assuming paper is homogeneous (I suppose it is close enough,) and you wear gloves to avoid adding finger oils to the paper, and you've drawn and cut carefully, the mass of the cut out curves of paper can be used to find relative area.  Again, the instructor will let you know if they like the idea or not.