Abstract: Determination of Trace Amount of Potassium and Manganese in Acid Rain Standard Reference Material by IDMSWang Jun;Zhao Motian (National Research Centre for Certified Reference Materials,Beijing 100013,China)Abstract:In this paper the isotope dilution mass spectrometry (IDMS) method for trace amount of potassium and manganese in acid rain SRM is described. The problems about how to eliminate the contamination,reduce blanks and raise the precision of measurements are studied.Keywords: IDMS,acid rain, potassium,manganese