how to determine peak area of chromatograms?

[sana70]

hi every body
is there a specific method in GC chromatography for determine peak area?
determine start and end of the peak sometimes depended on person.

[sbashkyrtsev]

What do you mean by "method"? Area is calculated by your software and it will depend on:

- Peak lift off and touch down points
- Baseline position
- Integration algorithm (trapezoidal, simpson's rule, fitting a model)
- Units

Chromatographic software usually has algorithms for automated peak & baseline detection, and also allows to override the results manually.

You're right that 2 different people will decide on 2 different Touch Down & Lift Off points, as well as on 2 different baselines. Same with 2 different software. You won't be able to change personal perception of people or the fact that software use different algorithms.

What you can do is decide on 1 particular method (or at least use similar methods) so that you can compare the results of 2 different runs. The actual numbers are not as important, but they should give consistent results when you compare 2 chromatograms.

For that to happen you may decide to use the same parameters for automated peak detection on both chromatograms. But your runs also need to have the same LC & Detector methods and ideally give high quality results (not too much noise, peaks are well resolved, not too much baseline drift). In case of low quality chromatograms the software may not be able to give precise results.

[Multidimensional]

It does depend on the detection settings used, the data acquired, the specific brand and type of CDS used and yes, the person performing the data analysis too. There is no single set of integration settings that can be used for all samples. The integration settings must be individually optimized for each specific method. This is part of the method development process.