Chromatography Forum

I have to detect the presence of Tetrodotoxin in puffer fishes through GC-Ms. My final extract was made into a residue via evaporation through lyophilization and direct bunsen flame. But the residue is insoluble in my derivatizing agent MSTFA. I need to know why it is insoluble and a solution to troubleshoot this problem

I have no firsthand experience with this derivatization, but have you read this paper?
http://s3.amazonaws.com/academia.edu.d ... rs_usi.pdf

The methods section may be useful.