一种新型气态亚硝酸校准源的开发与性能评估
- Development and performance evaluation of a novel calibrated source of gas-phase nitrous acid for CIMS
- 基金项目：国家自然科学基金（22374090）、国家重点研发项目（2022YFC3700203）、泰山青年学者（tsqn201909039）、济南市科技局高校20条（2021GXRC058）、博士后研究金项目（GZB20240401）、博士后科学基金（2024M751796）、山东青年项目（ZR2024QB272）
- 摘要：气态亚硝酸（HONO）作为大气中的关键痕量活性成分，是OH自由基的重要储库与来源，稳定、可调节的HONO校准源对于准确地测量大气HONO至关重要。在这项工作中，本课题组开发了一套可匹配化学电离质谱（CIMS）的新型HONO校准源，并针对该校准源进行了全面的性能测试。该HONO校准源基于一氧化氮（NO）、氧气（O2）和水（H2O）在高温条件下生成HONO，反应原料简单易得，过程中无废液产生，有效规避了酸置换法的缺点。HONO的浓度输出范围取决于NO标准气体的浓度，可通过改变NO气体流量在2 min内迅速调节HONO输出浓度。在5倍稀释条件下，本文所述方法输出的HONO浓度范围为0.48~13.35 μg/m3，浓度水平与温度（R2 = 0.990）、湿度（R2 = 0.984）、NO浓度（R2 ≥ 0.996）呈正相关关系。该校准源具备优秀的长期稳定性（RSD = 1.33%）与重现性（RSD ≤ 1.76%），输出气体的湿度可在0%~70%的相对湿度范围内调节，可满足CIMS等对湿度敏感仪器的校准需求。通过与本课题组自主研发的CIMS结合，验证了其作为HONO校准源的可行性。
- Abstract：A stable and tunable calibration source of gas-phase nitrous acid (HONO) is essential for the accurate and precise quantitative measurement of atmospheric HONO. In this work, a compact, stable and tunable novel HONO calibration source has been developed for chemical ionization mass spectrometry (CIMS) analysis, based on the reaction between NO, O2 and H2O at high temperature (200~625 oC). This HONO calibration source uses simple and readily available reactants, and the whole process does not produce waste liquid, avoiding the disadvantages of the acid substitution methods. The HONO generation is stable and rapid, with the output concentration adjustable within 2 minutes by altering NO concentration. The concentration range of HONO output depends on the concentration of NO standard gas used. Under the experimental conditions in this study, the produced HONO concentration range at 5-fold dilution is 0.48~13.35 μg/m3 with output levels positively correlating with temperature (R2 = 0.990), humidity (R2 = 0.984) and NO concentration (R2 ≥ 0.996). The source demonstrates superior long-term stability (RSD = 1.33%) and reproducibility (RSD ≤ 1.76%). A key feature of this system is the ability to precisely adjust the output gas humidity within a range of 0%-70% relative humidity, aligning with the calibration needs of CIMS and other humidity-sensitive applications. By integrating with a custom-built CIMS, the feasibility of this HONO calibration source has been verified. Therefore, this novel source has a significant potential for application, adeptly fulfilling the external calibration requirements for CIMS.
