动态法评价等离子体发射检测器的线性和检出限

Evaluation of the linearity and detection limit of plasma emission detector by dynamic volumetric method

根据ISO 6145–7:2009设计和研制了大量程气体动态稀释装置,稀释倍数为20~30 000,流量输出为0.5~3 L/min,相对扩展不确定度为2.2%(k=2)。采用以重量法制备的高纯氦气中8组分混合气体对稀释装置的准确性进行验证,利用装置发生的氦中8组分低含量混合气对气相色谱等离子体发射检测器的线性和检出限进行评价,结果显示等离子体发射检测器对氢气、氖气、氧气和甲烷的检测灵敏度很高,检出限可达5 nmol/mol以下,8组分气体在等离子体发射检测器上的线性拟合系数均大于0.999 9。仪器默认滤光片在氮气含量范围较大时产生非线性响应,更换滤光片后结果满意。

A wide range gas dilution device by dynamic volumetric method was developed according to ISO 6145-7:2009.When the range of gas output flow was from 0.5 to 3 L/min,the dilution times was from 20 to 30 000,the expanded uncertainty of the dilution device was 2.2%(k=2).The dilution device was validated by the gas standards with 8 components in high purity helium prepared by gravimetric method.The linearity and detection limit of the plasma emission detector for gas chromatography was evaluated by low concentration mixture gas with 8 components in high purity helium which generated by dilution device.The results showed that the sensitivity of plasma emission detector for hydrogen,neon,oxygen and methane was high,the detection limit was less than 5 nmol/mol and the coefficient of line fitting of 8 components was more than 0.999 9.The response of the filter for nitrogen which suggested by factory was not linearity when the testing range was wide,but the satisfied testing result was obtained after changing another filter.