Measurements of formaldehyde by PTR-MS during the SHARP field experiment in Houston, TX

An improved method of measuring formaldehyde with a PTR-MS instrument is reported. By removing water vapor from the sample air using a cold trap cooled to -30 C, a factor of 8 increase in the sensitivity of the instrument to formaldehyde was demonstrated. The reduction of water vapor allowed the PTR-MS instrument to be operated at low drift field intensities, allowing for the potential measurement of methylhydroperoxide, an important chain termination product in tropospheric photochemistry. The data show distinct diel cycles of formaldehyde and methylhydroperoxide under clean air conditions when winds were form the south of Houston, and elevated levels of formaldehyde when winds were from the north-east and impacted by industrial emissions from the Houston Ship Channel area. We report a description of the sample methodology and preliminary analysis of formaldehyde, methylhydroperoxide and other volatile organic compound data in the context of understanding the significance of industrial emissions of HCHO from refineries and chemical industrial within the Houston Ship Channel.