The use of a transportable Fourier transform infrared (FTIR) spectrometer for the direct measurement of solvents in breath and ambient air--I: Methanol.

A transportable Fourier transform infrared (FTIR) spectrometer has been tested for analysis of methanol vapor in alveolar and ambient air. The instrument has been found to be accurate and precise for both uses. The regions used for methanol and CO2 quantification are in the vicinity of 950-1100 cm-1 and 2000-2100 cm-1, respectively. The results of a standard addition experiment show a correlation coefficient of 0.97-0.99 for methanol in alveolar or ambient air at the 30-200 ppm concentration level. For CO2 analysis in 23 alveolar air samples at the 6.1-7.6% concentration level, the mean difference in results between a nondispersive infrared (NDIR) spectrometer and the FTIR was -0.092% with a standard deviation of 0.273% (p greater than 0.1). Methanol concentrations in alveolar air paralleled simultaneous measurements of methanol concentration in blood. Overall, these preliminary results suggest that FTIR spectroscopy is a practical and efficient approach for simultaneous biological and area monitoring of human exposure to organic solvents.