环境空气VOCs在线监测中标准气体的比对研究

环境空气中挥发性有机物(VOCs)的在线监测技术近年来受到普遍关注。相对于传统的离线手工监测,在线监测能够解决监测数据时空代表性不足的问题,同时更好地满足环境质量连续监测和研究的需要。现有环境空气常规气体在线监测技术规范对量值溯源有较高的要求,其中标准气体的溯源和比对是质量控制和质量保证的根本。通过构建上海市环境空气VOCs在线监测的标准气体实验室比对测试流程,提出了标准气体比对结果的评价指标及方法,以确保在线监测数据的准确性和可比性。结果显示,6瓶臭氧前体混合物标准气体中,90%以上物种的测定结果的相对偏差在±10%以内,个别物种超出范围,说明定期开展标准气体比对对于VOCs在线监测的质控和质保具有重要意义。

Research on the Standard Gas Comparison for Online Monitoring of Volatile Organic Compounds in Ambient Air

The online monitoring technology of volatile organic compounds (VOCs) in the ambient air has received widespread attention and development in recent years. Compared with traditional offline manual monitoring, online monitoring can solve the problem of insufficient spatial and temporal representativeness of data, and meet the needs of continuous monitoring and research on atmospheric environmental quality. The existing technical specifications of online monitoring system of conventional components for ambient air quality present high demand on value traceability. The traceability and comparison of the standard gas is the basis to ensure the accuracy of the monitoring data. This paper built the standard gas comparison process for VOCs online monitoring in Shanghai ambient air and put forward evaluation indicators and methods for comparison results to ensure single-site accuracy and multi-site comparability of online monitoring data. Results showed that the relative deviation of the measurement of more than 90% species was within ±10%. Some species of standard gas were out of range, which indicated great significance of regular comparison of the standard gas for quality control and assurance.