1.1 本试验方法描述了一种使用化学电离质谱仪测量各种挥发性有机化合物含量，从而产生带正电目标化合物离子的量化结果的技术。根据所谓初级离子的产生性质，能够进行此类分析的相关仪器被称为质子转移反应质谱仪（PTR-MS）、选定的离子流管质谱仪（SIFT-MS）或中压化学电离质谱仪（MPCI）- MS）。在本标准中，术语PTR-MS用于表示任何此类仪器。 1.2 任何一种仪器类型都可以与市场上的两种主要质量分析仪一起使用，即四极（QMS）或飞行时间（TOFMS）质量分析仪。该方法仅涉及分析的量化部分。由于主要仪器供应商的仪器用户界面和操作程序存在很大差异，本方法中未描述仪器操作的细节。 1.3 本标准包含了有关离子产生和化学反应的理论方面的详细信息，以了解蒸汽侵入分析领域中仪器的量化方面和实际操作。 仪器的操作和/或校准细节需要通过使用单个仪器供应商的用户手册来确定。袁等人（2017）等多篇出版物对该技术进行了全面讨论，包括单个质量线干扰和与替代方法的深入比较 ( 1. ) Dunne等人（2018年） ( 2. ) 2. . 1.4 单位- 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。以国际单位制以外的单位报告试验结果不应视为不符合本标准。 1.5 所有观察值和计算值应符合实践中确定的有效数字和舍入准则 D6026 . 1.5.1 用于指定如何在标准中收集/记录或计算数据的程序被视为行业标准。此外，它们代表了通常应保留的有效数字。使用的程序不考虑材料变化、获取数据的目的、特殊目的研究或用户目标的任何考虑因素；通常的做法是增加或减少报告数据的有效位数，以与这些考虑因素相称。 考虑工程数据分析方法中使用的有效数字超出了本标准的范围。 1.6 本标准可能涉及危险材料、操作和设备。 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 传统上，蒸汽侵入测试是使用多个碳罐样品或热解吸管样品进行的。这些不连续的测量结果被证明是快照，并提供了暴露的平均值。在许多情况下，需要更高的时间分辨率来识别由于特定占用或环境变化而产生的排放峰值。对于这些情况，需要一种连续实时监测解决方案。这些连续监测设置可以是短期的，也可以是长期监测的一部分- ASTM指南“蒸汽缓解系统长期监测计划制定标准指南”中所述的长期监测计划( E2600 ). 5.2 PTR-MS可在超痕量水平（即在µL/L（ppm）至小于pL/L（ppt）范围内）实时测量多种挥发性有机物。与气相色谱仪（GC）系统相比，其优势在于能够实时、连续地测量挥发性有机物（即，使用飞行时间分析仪，约1 Hz或更快），并且样品预处理有限，气相色谱仪（GC）系统通常是使用各种检测器测量挥发性有机物的首选方法。 对于带有四极分析器的PTR-MS，这些项将接近实时且半连续。在研究导致不可预测、突然和短期波动的大气化学或源排放时，通常需要秒范围内PTR-MS测量的高时间分辨率。有关不同类型PTR-MS的设计、理论和操作实践方面的详细说明，请参阅袁等人（2017） ( 1. ) . 5.3 对于环境空气测量，如蒸汽侵入（VI）相关排放测试，PTR- MS可用于三种不同的操作模式:( 1. )在扫描模式下，识别建筑物内的来源和VI入口点；( 2. )在变异识别模式下，作为连续监测仪器，时间分辨率为秒到分钟，覆盖大量挥发性有机化合物；( 3. )在源跟踪模式下，作为室内和室外源的扫描仪，并作为外部排放的快速跟踪设备；这需要将仪器安装在可移动的平台上，例如（自动）车辆或手推车上。根据应用的不同，可以使用相同的操作来识别空气中的各种其他成分，无论是有毒物质或非法物质的无组织排放，还是对以不同呼吸排放表示的感染的代谢反应。 5.4 空间和时间变异性是环境空气测量和源评估的两个常见挑战。在给定的建筑物内，蒸汽源可能很少，也可能很多，并且通常间隔不规则；它们可能被地板覆盖物、家具或墙壁遮挡，而这些本身可能是挥发性有机化合物的一大来源。当前选择的方法要求对特定采样点使用时间离散监测或时间平均监测。实时监测提供了一种评估蒸汽浓度空间分布的方法，这可能有助于快速有效地确定蒸汽入口点的位置。 5.5 实时评估作为具有两条或多条证据支持线的评估计划的一个组成部分很有价值，可用于: 5.5.1 为实时决策提供支持，例如何时何地收集长期样本，以便使用容器或吸附剂管进行固定实验室分析； 5.5.2 验证数据质量（例如，在采样前监测土壤气体探头吹扫的效果，提供泄漏检查；以及 5.5.3 测量VOC蒸汽浓度的变化，以响应建筑压力、温度、太阳辐射或其他天气条件的变化，以及影响蒸汽归宿和传输的因素，包括建筑内发生的二次化学反应。 5.5.4 根据事先确定的入侵化合物或此类途径内的排放物（如雨水排放），确定替代途径。 5.6 在房地产交易之前，根据现场特定的潜在关注源对房地产进行筛选。ASTM方法中描述了对房地产业务中潜在VI进行自愿调查评估的选项 E2600 -15. 注1: 本标准产生的结果的质量取决于执行该标准的人员的能力，以及所用设备和设施的适用性。 符合实践标准的机构 D3740 通常认为能够胜任和客观的测试/采样/检查等。本标准的用户应注意遵守惯例 D3740 本身并不能保证可靠的结果。可靠的结果取决于许多因素；实践 D3740 提供了一种评估其中一些因素的方法。

1.1 This test method describes a technique of quantifying the results from measuring various volatile organic compound contents using a chemical ionization mass spectrometer resulting in the production of positively charged target compound ions. Depending on the nature of production of so-called primary ions, the associated instruments having the capability to perform such analyses are either named Proton Transfer Reaction Mass Spectrometers (PTR-MS), Selected Ion Flow Tube Mass Spectrometers (SIFT-MS) or, in the most generic term, Mid-pressure chemical ionization mass spectrometers (MPCI-MS). Within this standard, the term PTR-MS is used to represent any of these instrumentations. 1.2 Either of the instrument types can be used with the two main mass analyzers on the market, that is, with either quadrupole (QMS) or time-of-flight (TOFMS) mass analyzer. This method relates only to the quantification portion of the analysis. Due to large differences in user interfaces and operating procedures for the instruments of the main instrument providers, the specifics on instrument operation are not described in this method. 1.3 Details on the theoretical aspects concerning ion production and chemical reactions are included in this standard as far as required to understand the quantification aspects and practical operation of the instrument in the field of vapor intrusion analyses. Specifics on the operation and/or calibration of the instrument need to be identified by using the user’s manual of the individual instrument vendor. A comprehensive discussion on the technique including individual mass-line interferences and in-depth comparison with alternate methods are given in multiple publications, such as Yuan et al. (2017) ( 1 ) and Dunne et al. (2018) ( 2 ) 2 . 1.4 Units— Values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard. 1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 . 1.5.1 The procedures used to specify how data are collected/recorded or calculated in the standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analysis methods for engineering data. 1.6 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Vapor intrusion testing has been performed traditionally using multiple canister samples or thermal desorption tube samples. These discontinuous measurements have been shown to be snapshots and provide averages of exposure. In many cases a higher temporal resolution is desirable to identify peaks of emissions due to specific occupancy or environmental changes. For these cases, a continuous real-time monitoring solution is desirable. These continuous monitoring setups can be either short-term or be part of a long-term monitoring plan as described in ASTM guide “Standard Guide for the development of LongTerm Monitoring Plans for Vapor Mitigation Systems” ( E2600 ). 5.2 The PTR-MS provides real-time measurement of multiple VOCs at ultra-trace levels, that is, in the µL/L (ppm) to less than pL/L (ppt) range. Its strengths lie with the ability to measure VOCs in real-time and continuously (that is, ~1 Hz or faster, using time-of-flight analyzers), and with limited sample pre-treatment, compared to a gas chromatograph (GC) system, which is commonly the method of choice to measure VOCs using a variety of detectors. In case of PTR-MS with quadrupole analyzers, the terms would be nearreal-time and semi-continuous. The high temporal resolution of the PTR-MS measurement in the range of second(s) is often desired when studying the atmospheric chemistry or source emissions that result in unpredictable, sudden, and short-term fluctuations. For a detailed description on the design and theory and practical aspects of operation for the different types of PTR-MS, please refer to Yuan et al. (2017) ( 1 ) . 5.3 For ambient air measurements, such as vapor intrusion (VI) related emission testing, the PTR-MS can be used in three different modes of operation: ( 1 ) in scanning mode to identify sources and VI entry points within buildings; ( 2 ) in variation identification mode, as a continuous monitoring instrument with seconds to minutes of temporal resolution covering a large number of VOCs; ( 3 ) in source tracking mode, as a scanner of indoor and outdoor sources and as a rapid tracking device for external emissions; this requires the instrument to be mounted on a moveable platform, such as on an (autonomous) vehicle or trolley. The same operation can be used to identify various other constituents in air, depending on the application—be it fugitive emissions from toxic materials or illicit materials, or metabolic reactions to infections expressed in different breath emissions. 5.4 Spatial and temporal variability are two common challenges with ambient air measurements and source assessments. Within a given building, the sources for vapors can be few or many and are generally irregularly spaced; they may be obscured from view by floor coverings, furniture or walls, which in itself can be a large source of VOC. The current methods of choice require the use of time-discreet monitoring or time-averaged monitoring of a specific sampling spot. Real-time monitoring provides a method to assess the spatial distribution of vapor concentrations, which may help to rapidly and efficiently identify the location of vapor entry points. 5.5 Real time assessment is valuable as a component of a program of assessment with two or more supporting lines of evidence and can be used to: 5.5.1 Provide support for real-time decisions such as where and when to collect long-term samples for fixed laboratory analysis using canisters or sorbent tubes; 5.5.2 Verify data quality (for example, monitoring the efficacy of soil gas probe purging prior to sampling, providing leak checks; and 5.5.3 Measure changes in VOC vapor concentrations in response to changes in building pressure, temperature, solar irradiation, or other weather conditions and factors affecting vapor fate and transport, including secondary chemistry occurring within the building. 5.5.4 Identify alternative pathways based on prior identified intrusion compounds or based on emissions within such pathways, such as stormwater drains. 5.6 Screening of a property prior to a real estate transaction based on site specific potential sources of concern. The option for voluntary investigative assessments of potential VI in the real estate business is described in ASTM method E2600 -15. Note 1: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.