Abstract: This invention claims processes that append a single nucleotide having a 3?-ONH2 moiety to the 3?-ends of an oligonucleotide primer using 3?-deoxynucleoside triphosphates that have, instead of a 3?-OH moiety, a 3?-ONH2 moiety, where the nucleotides contain both standard and non-standard nucleobases, and where as a key claim limitation, substantially no hydroxylamine is present in the solutions used in the claimed processes.