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peak area calculation

 
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lauracaponi



Joined: 21 Jul 2018
Posts: 3

PostPosted: Sat Jul 21, 2018 12:54 pm    Post subject: peak area calculation Reply with quote

Dear all, I am new to datagraph and I have a specific request.
I imported one of my chromatogram that produced a nice graph with several peaks. I need to calculate the area of some specific peak.

I used the plot action to integrate, but I obtained a cumulative integrated area under the whole curve, while I'd like to obtain the area of specific peaks.

Is there a way to select the borders of the peak on the graph to limit the integration to the specific peak?

Is there a way to move the x axis letting it cross the y axe above or below the zero (in other words to custom the origin of the axis)?

Thanks for your help.

Laura
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lauracaponi



Joined: 21 Jul 2018
Posts: 3

PostPosted: Tue Jul 31, 2018 4:15 am    Post subject: Re: peak area calculation Reply with quote

No suggestion? Is this the right place to ask this question?

Laura

lauracaponi wrote:
Dear all, I am new to datagraph and I have a specific request.
I imported one of my chromatogram that produced a nice graph with several peaks. I need to calculate the area of some specific peak.

I used the plot action to integrate, but I obtained a cumulative integrated area under the whole curve, while I'd like to obtain the area of specific peaks.

Is there a way to select the borders of the peak on the graph to limit the integration to the specific peak?

Is there a way to move the x axis letting it cross the y axe above or below the zero (in other words to custom the origin of the axis)?

Thanks for your help.

Laura
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Pamela



Joined: 25 Feb 2017
Posts: 41

PostPosted: Sat Aug 11, 2018 2:29 am    Post subject: Reply with quote

Laura,

Yes - this is a great place to ask questions so others can see. Sorry for the delayed response.

Here is a suggestion...

To integrate over specific areas, you can set up columns in the data table to identify the beginning and ending of each peak you want to integrate. Then use a Map column to pull the cumulative integral at those locations. The value at the beginning is subtracted from the value at the end to get the area under a specific peak.

To "move the x axis" you create a function that overlays where you want the axis to be and then you subtract that function from the data using a Plot action.

Here is a link to an example file that uses these techniques to integrate the area under these three peaks:
www.visualdatatools.com/phpFiles/20180810--Integrate/IntegratePeaks-SimpleExample.dgraph.zip

Does this help answer your questions?

Also, if you have an example data set you can also email it to help@visualdatatools.com and we can take a look at it.

Pamela



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lauracaponi



Joined: 21 Jul 2018
Posts: 3

PostPosted: Sat Aug 11, 2018 4:30 pm    Post subject: Reply with quote

Dear Pamela,

exactly the answer I needed Smile

The example file is a great way to explain the procedure in detail.
I' ve tried it with my data, and it works well.

Thank you very much.


Laura
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Pamela



Joined: 25 Feb 2017
Posts: 41

PostPosted: Sun Aug 12, 2018 12:11 pm    Post subject: Reply with quote

Excellent - Glad to hear this worked!
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