A sensitive and precise method for the determination of microgram amounts of zinc (II) has been developed. The ion associate of the anionic zinc (II)-thiocyanate complex with malachite green (MG) can be floated with the aid of small nitrogen bubbles, then dissolved in toluene. The formation of the ion associate takes place over a wide pH range (3-7). The method permits the determination of zinc (II) in the range 0–1.1 jig/ml and can be applied to samples of drinking water with good results.