2 peaks on GC-MS have close retention time could be the same compound?

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Why the CHi^2 is close to zero with a bad fitting but the Rp and Rwp are still high?

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Gnogbo Alexis Bahi

No, it cannot be the same compound but 2 compounds which have the same characteristics. It is therefore necessary to play on the composition of the solvents to properly separate them.

Didy Yoga Lucky Prayoga

Might be similar compound indeed. Try to modify your method until you get a good RS