C12 / C13

We analyzed the visible-range absorption spectra of C12 and disubstituted C13 glyoxal, an atmospheric trace gas associated with the oxidation of volatile organic compounds. Disubstituted C13 glyoxal has potential for use as a laboratory tracer. Using those spectra, we generated synthetic spectra containing C12 and C13 glyoxal at various resolutions and with different types of simulated instrumental noise. DOAS analysis of these simulated spectra allowed for the determination of experimental variance in outputs under numerous concentration and wavelength scenarios. We also conducted sensitivity tests to determine which wavelength ranges best differentiated the isotopically labeled and unlabeled gases. Because isotopic shifts in the spectra remained analytically meaningful at low (>0.7 nm) resolutions, near-real-time analysis of C12 and C13 glyoxal concentrations is theoretically possible.

Bruker 120 high-resolution Fourier transform spectrometer

Gas manifold used in the glyoxal-forming reaction