Stability of gaseous volatile organic compounds contained in gas cylinders with different internal wall treatments.

Jianrong Li,Annarita Baldan,George C. Rhoderick,Philippe Moussay,David R. Worton,Walter R. Miller,Detlev Helmig,Dalho Kim,Christina E. Cecelski,Jan W. Bottenheim,Joële Viallon,Sergi Moreno,Sangil Lee,Yong Doo Kim,Faraz Idrees,Paul J. Brewer

doi:10.1525/elementa.366

Abstract

Measurements of volatile organic compounds (VOCs) have been ongoing for decades to track growth rates and assist in curbing emissions of these compounds into the atmosphere. To accurately establish mole fraction trends and assess the role of these gas-phase compounds in atmospheric chemistry it is essential to have good calibration standards. A necessity and precursor to accurate VOC gas standards are the gas cylinders and the internal wall treatments that aid in maintaining the stability of the mixtures over long periods of time, measured in years. This paper will discuss the stability of VOC gas mixtures in different types of gas cylinders and internal wall treatments. Stability data will be given for 85 VOCs studied in gas mixtures by National Metrology Institutes and other agency laboratories. This evaluation of cylinder treatment materials is the outcome of an activity of the VOC Expert Group within the framework of the World Meteorological Organization (WMO) Global Atmospheric Watch (GAW) program.

Highlights

Maintaining consistent, long-term data measurement sets on volatile organic compounds (VOCs) requires sources of accurate and stable gas mixtures containing these compounds
Over the decades of VOC gas mixture stability research, many types of cylinders and internal wall treatments have been tested by National Metrology Institutes (NMIs)
NMIs are moving towards the development of VOC standards in an air matrix but have very limited stability data currently

Summary

Introduction

Maintaining consistent, long-term data measurement sets on volatile organic compounds (VOCs) requires sources of accurate and stable gas mixtures containing these compounds. Each NMI was tasked with developing standards for a specific group of VOCs, for which they were eventually established as a Central Calibration Laboratory (CCL) and tasked with providing standards to the World Calibration Centre It is well known among these laboratories developing and preparing VOC gas standards that a plain aluminum gas cylinder, with no special treatment to the internal cylinder walls, will not yield long-term, stable VOC gas mixtures.. The goal is to find a gas containment package that results in long-term stability, upwards of 10 years is preferred, of these VOCs in a gas mixture These internal cylinder treatments are proprietary and the authors cannot comment on the actual process used in applying those treatments.

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Conclusion