Fourier Transform Infrared Absorption Spectroscopy for Quantitative Analysis of Gas Mixtures at Low Temperatures for...

Area of Science:

• Analytical Chemistry
• Spectroscopy
• Environmental Science

Background:

• ASTM standards (E 2885-13, E 2933-13) define performance specifications for chemical vapor detectors.
• Accurate delivery of known chemical concentrations is crucial for detector performance evaluation.
• Referee methods are needed to validate test concentrations and uncertainties, especially for reactive analytes.

Purpose of the Study:

• To extend a Fourier transform infrared (FT-IR) absorption spectroscopy method for quantitative vapor stream analysis.
• To enable performance evaluation of chemical vapor detectors at sub-ambient temperatures (down to -5 °C).
• To provide in situ, real-time verification of analyte concentrations with characterized uncertainties.

Main Methods:

• Utilized primary reference spectra to establish initial analyte concentrations.
• Generated secondary reference spectra for measuring concentrations in specific low-temperature test environments (7 °C, -5 °C).
• Employed additional reference spectra and spectral profile strategies to address impurities and water condensation.

Main Results:

• Successfully adapted FT-IR spectroscopy for quantitative analysis of hazardous vapors at low temperatures.
• Mitigated uncertainties associated with impurities and water condensation in the low-temperature test cell.
• Demonstrated verification of test analyte concentrations with characterized uncertainties via in situ measurements.

Conclusions:

• The FT-IR method provides accurate, in situ verification of chemical vapor concentrations for detector testing at low temperatures.
• This approach offers near-real-time feedback and broad applicability to various toxic industrial chemicals.
• Enhances the reliability of chemical vapor detector performance standards under challenging environmental conditions.