On the existence of ‘bis (L-glutamine) potassium nitrate’ crystal

•Reported bis (L-glutamine) potassium nitrate crystal is actually L-glutamine.•Reported bis (L-glutamine) sodium nitrate crystal is actually L-glutamine.•Use of KNO3 or NaNO3 does not affect crystal growth of L-glutamine.

The slow evaporation of an aqueous solution containing L-glutamine and potassium nitrate in 2:1 mol ratio results in the fractional crystallization of L-glutamine and not the formation of a so called bis (L-glutamine) potassium nitrate as reported recently by Hanumantharao and Kalainathan (2012).

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