The present invention relates to a method of preventing modification of a synthetic oligonucleotide or oligonucleotide analog during removal of at least one -cyanoethyl protecting group from the oligonucleotide or oligonucleotide analog. The method involves contacting the oligonucleotide or oligonucleotide analog with a basic solution having at least one acrylonitrile scavenger, such as t-butylamine, at a sufficient temperature and for a sufficient period of time to remove at least one -cyanoethyl protecting group. The present invention also relates to a method of producing a synthetic oligonucleotide or oligonucleotide analog.