Removal of iodine by solid phase adsorption to charcoal following iodine oxidation of acetamidomethyl-protected peptide precursors to their disulfidebonded products: oxytocin and a Pre-S1 peptide of hepatitis B virus illustrate the method

Chemical quenching, gel filtration or liquid phase extraction procedures ar e currently in vogue for taking iodine off from the reaction mixtures in wh ich it is used to cause the formation of disulfide bonds in acetamidomethyl or trityl protected peptides. It has been found that charcoal effectively, selectively and rapidly removes iodine by solid phase extraction from reac tion mixtures in which it is used to convert the acetamidomethyl protected precursors of oxytocin or a peptide from the Pre-Si region of hepatitis B v irus into their intramolecularly disulfide-bonded products. The advantages of this new method, namely simplicity, rapidity, quantitative yields, freed om from side reactions, linear scalability, cost effectiveness and adsorpti on of iodine on to solid charcoal are discussed.