Cleanliness is indispensable in electronics production. Ionic contaminations in particular lead to a drastic worsening of the quality of the printed circuit boards. The present Application Note describes the determination of cations on printed circuit board surfaces. The intelligent Partial Loop Injection Technique (MiPT) used for this purpose permits the determination of cations and anions in the same sample. The determination of the anions is described in AN-S-317.