Hi Fabio,
You can try the X-Function wunstackcol.
I will assume that you have already imported your file into Origin worksheet:
1.Active Sheet1 where you imported your data into
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2.Run the script
wunstackcol irng1:=[Book3]Sheet1!(1,4) irng2:=col(3) pos:=append;
3.A worksheet will be created.
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More info about wunstackcol can be read here:
http://www.originlab.com/doc/X-Function/ref/wunstackcol
Hope it helps.
Regards,
Yuki
OriginLab