ASTM D8686-26

1.1 This practice covers procedures for measurement of volatile organic compounds (VOCs) using hydronium ion (H₃O⁺) ionization proton-transfer reaction mass spectrometry (PTR-MS) under environmental conditions that are typical of those found in indoor environments, such as offices, residential buildings, and test chambers. Procedures to prepare and initialize an instrument for measurement, construct a sampling line and characterize performance, and convert instrument signal into indoor air concentrations are outlined. These procedures can be used to develop standard operating procedures for specific PTR-MS applications.

1.2 The scope is limited to PTR-MS and is not inclusive of other reagent ions that can be used in real-time chemical ionization mass spectrometers.

1.3 PTR-MS is used in this practice to describe a chemical ionization mass spectrometer that satisfies all the following criteria: capable of ionizing analytes with H₃O⁺ as the primary reagent ion, real-time (that is, at least 1 Hz) data acquisition, and is field-deployable. From this point on all instances of PTR-MS refer to the instrument and “proton-transfer reaction mass spectrometry” will be used when referring to the technique.

1.4 Because the logistics and data quality objectives of each application using a PTR-MS will be unique, standardized procedures for measuring the concentrations of specific gases are not explicitly set forth in this practice. Instead, general procedures that are applicable to all PTR-MS instruments and most applications are described. Users should consult manufacturers for instrument-specific guidance or refer to scientific literature, or both, when considering applications not covered by this practice.

1.5 This practice describes procedures appropriate for both short-term (for example, minutes to hours) and long-term (for example, days to weeks) sampling of indoor air.

1.6 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.7 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.

1.8 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.