On the atmospheric degradation of pyruvic acid in the gas phase

The pulsed laser photolysis-laser induced fluorescence (PLP-LIF) technique has been used to measure the rate constant for the gas phase reaction of OH radicals with pyruvic acid (CH3C(O)C(O)OH) in the temperature range 273–371 K. The data obtained were found to be well represented by the conventional Arrhenius expression: kPA=(4.9±1.9)×10−14 exp[(276±123)/T] cm3 molecule−1 s−1, and at 298 K, kPA=(1.2±0.4)×10−13 cm3 molecule−1 s−1. In addition, the UV-Vis absorption cross-sections of pyruvic acid were measured in the wavelength range 290–380 nm at 298 K; the obtained values are compared with literature ones. Using the PLP-LIF system, the photolysis of pyruvic acid was found to yield OH radicals with a quantum yield of 5±3% at 355 nm. Evidence was also found for the OH production from the photolysis of pyruvic acid using a set of black lamps as the light source. The data obtained confirm that the photolysis is the major gas phase atmospheric loss process of pyruvic acid.