Abstract: The invention provides a process for detecting the presence of guanidinium ions in a sample solution. The detection process involves contacting a sample solution suspected of containing guanidinium ions with a cation exchange resin and eluting the guanidinium ions present in the sample solution with an aqueous buffer solution having a pH of about 1.5 to about 2. This is followed by contacting the eluant with a cation suppressor column and simultaneously flowing a suppressor regenerate solution in the opposite direction on the opposite side of the permeable membrane of the column, and finally, detecting the presence of guanidinium ions in the eluant from the ion exchange column which was contacted with the suppressor column by use of a conductivity detector.