测量火灾烟气中痕量氰化氢的高灵敏负离子化学电离质谱方法的研究

Hydrogen cyanide (HCN) in fire smoke is infamous as a highly poisonous gas and has been the main reason for causing fire victims to death in fire scenes. Therefore, it is urgently necessary to develop an accurate, on-line, and highly sensitive method for investigating the formation mechanism and toxicity assessment of HCN in the fire smoke. The chemical ionization mass spectrometry is such an on-line method to determine HCN with high sensitivity. However, the current ionization methods mostly utilize ion association reactions to produce product ions with large mass-to-charge (m/z), and thus suffered seriously from the interferences of sample humidity on reagent ions and background ion peaks on product ion peak, which caused poor sensitivity or accuracy and failure in direct determination of HCN in the fire smoke with complicated components. This application is going to develop an atmospheric pressure negative-ion ionization source based on 63Ni ion source to produce reagent ion O2- with high concentration. The reagent ion O2- will be adopted to react with HCN to produce CN- with low m/z and the interference of the background ions will be eliminated. Extended ion-molecule reaction tube with high efficiency is to be designed and the production efficiency of CN- will be improved by controlling electric intensity in the reaction tube and enhancing the reaction rate. Based on refraction effect generated by the non-uniform electric field among thick electrodes, the ions will be focused periodically in the reaction tube to guarantee the high transmission efficiency and improve the sensitivity of the product ions. The real-time and dynamic method proposed by this project will not only assess the toxicity risk of the fire smoke in the fire scenes，but also can study the formation mechanism and kinetics of HCN released from new decoration materials.

火灾烟气的氰化氢（HCN）是一种剧毒化合物，已成为人员毒烟气致死的主因。研究火灾中痕量HCN的生成机制及毒性评价，需要一种准确在线高灵敏测量HCN的方法。化学电离质谱法是一种在线高灵敏测量技术，但现有电离方法多采用离子缔和反应，产物离子质荷比（m/z）较大，不仅受样品湿度影响，而且背景离子干扰严重，导致灵敏度不高或准确性不好，无法直接测量化学成分极其复杂的烟气中HCN。本申请拟采用大气压负离子63Ni电离源产生高浓度试剂离子O2-与HCN反应产生CN-（m/z 26），消除了背景离子峰的干扰。拟设计高效率加长离子-分子反应管，并控制其电场强度增强反应速度提高CN-的产生效率；利用厚电极非均匀电场产生的折射效应，实现离子在反应管的周期聚焦，保证离子高效传输，提高灵敏度。本项目发展的实时动态测量HCN的方法，不仅可用于火灾现场烟气的毒害风险评估，还可用于装饰新材料释放HCN的机理和动力学研究。

火灾烟气的氰化氢（HCN）是一种剧毒化合物，已成为人员毒烟气致死的主因。研究火灾中痕量HCN的生成机制及毒性评价，需要一种准确在线高灵敏测量HCN的方法。化学电离质谱法是一种在线高灵敏测量技术，但现有电离方法多采用离子缔和反应，产物离子质荷比（m/z）较大，不仅受样品湿度影响，而且背景离子干扰严重，导致灵敏度不高或准确性不好，无法直接测量化学成分极其复杂的烟气中HCN。本申请采用了基于真空紫外灯（VUV灯）的大气压负离子光电离化学电离源产生高浓度的试剂离子O2-（m/z 32），可与HCN反应产生团簇离子[HCNO2]-（m/z 59）和离子CN-（m/z 26），以离子CN-（m/z 26）为HCN的特征离子，消除了背景离子峰的干扰。本研究采用了源内碰撞诱导解离（CID）技术，实现了团簇离子[HCNO2]-（m/z 59）的有效解离，特征离子CN-（m/z 26）的信号强度提高了24倍，从而提高了HCN的分析灵敏度。鉴于火灾现场烟气组分复杂，考察了浓度较高的组分如H2O、CO2对HCN电离的影响，建立了火灾现场烟气中HCN的准确定性和定量分析方法，并用于布料燃烧烟气中HCN的在线监测和毒害风险评估。