A Miniature Electrical Furnace as an Excitation Source for Low-Temperature, Gas-Phase, Infrared Emission Spectroscopy

Abstract

The analytical utility of low-temperature, gas-phase infrared emission spectroscopy is studied with the use of a specially designed miniature electrical furnace. This furnace, designed to minimize blackbody radiation from the source itself, was capable of operating between 100 and 1000°C and producing infrared emission from parent analyte molecules, as opposed to their terminal combustion products, such as CO2 and H2O. The low-temperature, infrared emission spectra of nitrous oxide (225°C) and methyl benzoate (250 and 700°C) are reported, and the feasibility of determining ethanol in gasohol is evaluated with the use of the alcohol C-O stretching vibration (observed at 1070 cm−1 in emission). The detection limit for ethanol in gasohol at 202°C was found to be 0.124% v/v, and the relative standard deviation of eight single-scan determinations of ethanol in a 10% v/v gasohol blend was found to be 4.01%. Some of the advantages and limitations associated with analytical, low-temperature, gas-phase, infrared emission spectroscopy are discussed and compared with results obtained with a hydrogen/air flame as the excitation source.