Abstract: QA/QC Internal Standard Method for the Determination of Semivolatile Organic Pollutants in Waste Water by GC/MSShi Junhui;Zhou Chunyu (National Environmental Analysis and Measurement Center,Beijing 100012,China) Dong Fengxia; Wang Conghui (Institute of Forensic Science,Beijing 100038,China) Abstract:According to the requirments of statement of work for organic analysis and its quality assurance/quality control (QA/QC) of US EPA contract laboratory program (CLP), The inter-standard quantitative analysis of semivolatile organic compounds in waste water has been perfomed in China for the first time. 16 kinds of compounds belonging to the prior pollutants of US EPA method including 4 kinds of prior pollutants in China have been detected in secondary treatment sewage of a sewage treatment plant.Their concentrations were between 3. 12 and 41. 4 ng which less than emission standard values permitted. 9 kinds of trail compounds which less than emission standard values permitted. 9 kinds of trail compounds which are non-toxic,such as aliphatic hydrocarbon,carbohydrate and the acids were between 1. 3 to 39. 9ng. The analytical speed can be elevated by adopting this method,and its results are very reliable. The secondary treatment effluents of this sweage treatment plant meet the requiment for national emission standard. Keywords: inter-standard quantitative method,relative response factor, recovery indicator, QA/QC