Abstract: To achieve low-cost and accurate determination of platinum with high content in platinum-carbon catalyst samples, ammonium chloroplatinate gravimetric method was adopted to determine the platinum with major content, while inductively coupled plasma atomic emission spectrometry (ICP-AES) was adopted to determine the platinum with trace content. The total platinum content in the sample was calculated as the sum of the above two. The 0.200 0 g of sample was taken, and 10 mL of hydrochloric acid and 5 mL of nitric acid were added. The mixture was heated at 200 ℃ for 10 min, followed by the addition of 5 mL of perchloric acid. The mixture was heated at 280 ℃ until the sample was completely dissolved. Then, 5 mL of hydrochloric acid was added, the solution was evaporated to near dryness at 200 ℃, and this step was repeated twice. The residue was collected, and 2 mL of hydrochloric acid and 8 mL of water were added. Subsequently, 50 mL of the saturated ammonium chloride solution at (85±5) ℃ was slowly added while stirring, and the solution was evaporated to near dryness at 150 ℃. After cooling, water was added while stirring to completely dissolve the remaining ammonium chloride crystals, and the solution was settled for 12 h. After filtering using quantitative filter paper, the precipitate was washed, which wrapped in the filter paper was transferred to a pre-weighed porcelain crucible and heated in an electric furnace under programmed temperature conditions until the filter paper was completely dried and ashed. Heating was stopped when white smoke disappeared, and the porcelain crucible was removed and calcined at 900 ℃ for 2 h. After cooling, the porcelain crucible was weighed, and the mass fraction of major platinum was calculated. The filtrate was heated and concentrated at 180 ℃. When the volume became smaller to the precipitation of ammonium chloride crystals, 20 mL of nitric acid was slowly added, the solution obtained was heated at 180 ℃ to decompose the ammonium chloride, and this step was repeated until no more ammonium chloride crystals precipitated. The solution was heated at 180 ℃ until approximately 2 mL remained, and 10 mL of hydrochloric acid was added. The solution was heated to boiling, and diluted with water to 100 mL after cooling. Trace platinum was determined by ICP-AES at the analytical wavelength of 214.423 nm. It was shown that linear relationship between values of the mass concentration and spectral line intensity of platinum was kept within 20.00 mg · L⁻¹ for ICP-AES, with a detection limit （3s） of 0.013 8 mg · L⁻¹. RSDs of 10 repeated determinations of the actual sample was 0.17%, and the recovery of platinum obtained by the standard addition method ranged from 98.9% to 103%.