Abstract: The Tin reacts with alphazurine A (C₃₇H₃₅N₂O₆S₂Na) in NH₃ medium to form an ionic associate. The optimum condition influencing the reaction have been predicted. A new method for the determination of trace ions was developed. The alphazurine A Sn(IV) ion association complex exhibits maximum absorption at 630 nm with an apparent molar absorptivity of 1.7×10⁶ L/(mol·cm). Beer's law is obeyed in the range of 0～80 μg/L for Sn(IV). The proposed method has been used for the determination of Sn(IV) in water and canned food with satisfactory results.