Flow analysis method for determining the concentration of methanol and ethanol in the gas phase using the nitrite formation reaction

This paper presents a flow determination method for low molecular weight al cohols (methanol, ethanol) in the gas phase using the nitrite formation rea ction, which was developed from an earlier method using a glass bottle, In this method, the ambient air and nitrogen dioxide (1000 ppmv) were allowed to continuously flow in a glass tube, which had been filled with 10 g of Py rex glass beads. The now rates of the ambient air and nitrogen dioxide were 30 and 20 cm(3)/min, respectively. The gas-phase alkyl nitrites produced b y the dark reaction of atmospheric alcohols and nitrogen dioxide on the Pyr ex glass beads were then analyzed by gas chromatography with an electron ca pture detector. The alcohol concentrations of the samples were calculated u sing a calibrated conversion factor for each alcohol to its nitrite. The de tection limits for the methanol and ethanol are 0.7 and 0.5 ppbv, respectiv ely. This flow method was used to determine the atmospheric alcohol concent rations and was found to have the advantages of a short sampling time and s imple quantitative procedure compared with the previously reported method ( glass bottle method). The feasibility of this method was also established.