“罐采样-实验室分析”测定环境空气中117种挥发性有机物要点分析

“罐采样-实验室分析”是当前测定环境空气中挥发性有机物的主流方法。结合已有资料,针对方法涉及的采样、样品运输与保存、分析测试等环节,考察了环境空气中挥发性有机物监测的主要影响因素。罐选择、清洁度、气密性、惰性化是样品保存的先决条件;采样流量控制器的气密性、流量校准等是保证监测准确的基本要素;温度变化对样品保存产生影响;标准气体的湿度、配置平衡时间、保存时间、配制准确性和内标气体的保存时间等会导致校准和溯源产生偏差。样品中的水分及二氧化碳是分析过程中影响监测结果准确性的干扰因素,实验室有机溶剂也会干扰分析的准确性。

Study on the Key Points of “ Canister Sampling-Laboratory Analysis” for the Determination of 117 Volatile Organic Compounds in Ambient Air

Canister sampling-laboratory analysis is the current mainstream method for the determination of volatile organic compounds in ambient air. Based on the existing datum, this study investigates the main influencing factors of volatile organic compounds monitoring in ambient air, including sampling, sample transportation, sample preservation and analysis. The results show that canister selection,cleanliness,air tightness and inertness are the prerequisites for sample preservation. Air tightness and flow calibration of the sampling flow controller are essential elements to ensure accurate monitoring. Sample preservation is affected by temperature change. Calibration and traceability deviation may occur due to humidity of standard gas, configuration balance time,storage time,preparation accuracy and storage time of internal standard gas. In addition,the moisture and carbon dioxide in the samples are the interference factors that affect the accuracy of the monitoring results. Laboratory organic solvents also affect the accuracy of analysis results.