Part 4 of this standard specifies a method for the determination of lead content in alloy gold, which is applicable to samples such as mining gold, smelting crude gold products and recovered gold with lead mass fraction in the range of 1.00% to 15.00%. Methods The sample was analyzed by dilute nitric acid and muriatic acid, silver was separated by silver chloride settling, gold was reduced by sulfite, and lead sulfate was used to settle lead sulfate. Subsequently, the lead sulfate was dissolved in an acetic acid-Sodiumacetate buffer solution with xylenol orange as the indicator, and titrated with EDTA standard titration solution at pH 5.5 to 6.0. The mass fraction of lead was calculated by the volume of EDTA solution consumed.