Any amino acid gives reaction with ninhydrin; your skin gets a purple color in contact with ninhydrin; therefore any protein extract will react.

Please look at the following below links which may help you in your analysis:

https://pdfs.semanticscholar.org/19a0/885bc303e628bcd43d27ee03c9298cbe568a.pdf

https://eurekamag.com/pdf/004/004399510.pdf

http://www.chem.boun.edu.tr/wp-content/uploads/2014/04/Chem-415-Experiment-2.pdf

Thanks

Any trace of protein can give a positive ninhydrin test. Even fingerprints give a ninhydrin color (which is often used to find them).

L-LEUCINE,GLYCINE WILL ANSWER NINHYDRIN TEST,EVEN IMIDAZOLE

Ninhydrin test is characteristic test for proteins. Very small quantities of proteins or amino acids (building blocks of proteins) will give positive ninhydrin test.