You could also try a higher boiling keytone.
Thujone comes to mind as accessable one.
http://chemfinder.com (http://chemfinder.com)
for the structure if interested
http://www.execpc.com/~goodscnt/data/es1040992.html (http://www.execpc.com/~goodscnt/data/es1040992.html)
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How was the tryptamine isolated? If the reaction did not produce more than 2% tryptamine, then you should be able to recover the rest of the tryptophan unchanged.
https://www.rhodium.ws (https://www.rhodium.ws)