环境监测用正己烷气体标准样品的研制

采用称量法通过两步稀释制备了含量水平为1μmol/mol的氮气中正己烷气体标准样品,考察了气瓶内壁吸附作用、制备重现性、瓶内均匀性、时间稳定性等相关因素的影响,并将该正己烷气体标准样品与同类气体标准样品进行了比较。结果表明:该正己烷气体标准样品的最低使用压力为1 MPa,有效期为12个月(0~38℃),相对扩展不确定度(k=2)为2%;该正己烷气体标准样品的量值与同类标准样品具有可比性,可为相关环境监测工作提供技术支持。

Preparation of n-hexane standard gas for environmental monitoring

The n-hexane standard gas with 1 μmol/mol of concentration level was prepared in nitrogen by gravimetric method and two-step dilution process. The affecting factors were investigated,such as：the adsorbability of the cylinder inner wall,the reproducibility of the preparation process,the uniformity and time stability of gas in the cylinder. Moreover,the n-hexane standard gas was compared with other same type standard sample. The result showed that：The minimum using pressure was 1 MPa,the valid term was 12 months（at 0-38 ℃）and the relative expanded uncertainty（k=2）was 2% for the n-hexane standard gas;The value of the n-hexane standard gas was comparable to the same type standard sample,which could provide technical support for environmental monitoring.