Abstract: Isobaric ions interfere with two isotopes of Ag during determination by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), i.e., ⁹⁰Zr¹⁶O¹H and ⁹¹Zr¹⁶O on ¹⁰⁷Ag, and ⁹²Zr¹⁶O¹H and ⁹³Nb¹⁶O on ¹⁰⁹Ag. Although an interference correction coefficient method was used for the calibration of the analytical results, the analytical errors remain serious. In the proposed method, samples were closed decomposed by nitric acid, hydrofluoric acid, and perchloric acid. Ammonia was used to precipitate Zr and the purified Ag was determined by ICP-MS using ¹⁰³Rh as the internal standard. The interference caused by the residual Zr was calibrated by the interference coefficient method. The method has a detection limit (3σ) of 4.1 ng/g and relative standard deviation (n=12) ranging from 2.5% to 7.8%. Determination of Ag in 53 primary certified materials of geochemical exploration indicates no loss of Ag. Using ammonium as the reagent, separation of Zr and Ag was successfully achieved due to the formation of the stable Ag-ammonium complex and Zr-hydroxide precipitate. The separation of Ag from Zr has reduced the interferences of Zr on Ag. Compared with the high-pressure sealed decomposition method and the P₅₀₇ extraction resin separation method, the closed sample decomposition method is much simpler with less acid used and a lower blank.