conventional dyalisis with dyalisis tubes against large volumes of low salt buffer or milli Q water

TCA precipitation sometimes work

..Thanks for your suggestions ..  

well,  for detecting the presence or absence of  advance glycation end products ..which of the above is good? 

peptides may usually be precipitated in 10 volume cold diethyl ether.

small volume of proteins can be dialysed by placing a drop on a membrane (with low MW cut-off) floating on a beaker of water (or new buffer)