SUB-PARTS PER BILLION DETECTION OF ISOPRENE USING A REDUCTION GAS DETECTOR WITH A PORTABLE GAS-CHROMATOGRAPH

Isoprene, a biogenic hydrocarbon emitted from vegetation, has been det ected at sub-ppb levels, using a commercially available reduction gas detector (RGD) with an isothermal, portable gas chromatograph. For 1 m l samples, a detection limit of 300-500 parts per trillion (over an or der of magnitude less than the traditional gas chromatography-flame io nization detection technique [GC-FID]) was achieved. The detector resp onse was linear up to 500 ppb. This technique (GC-RGD) is compared wit h GC-FID measurements in studies of ambient isoprene mixing ratios wit hin and above an oak forest in northeastern U.S.A. Applications to lab oratory studies of the mechanism of isoprene production at the leaf le vel are also discussed.