AIRBORNE MEASUREMENTS OF SULFUR-DIOXIDE, DIMETHYL SULFIDE, CARBON-DISULFIDE, AND CARBONYL SULFIDE BY ISOTOPE-DILUTION GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

A gas chromatograph/mass spectrometer is described for determining atm ospheric sulfur dioxide, carbon disulfide, dimethyl sulfide, and carbo nyl sulfide from aircraft and ship platforms. Isotopically labelled va riants of each analyte were used as internal standards to achieve high precision. The lower limit of detection for each species for an integ ration time of 3 min was 1 pptv for sulfur dioxide and dimethyl sulfid e and 0.2 pptv for carbon disulfide and carbonyl sulfide. All four spe cies were simultaneously determined with a sample frequency of one sam ple per 6 min or greater. When only one or two species were determined , a frequency of one sample per 4 min was achieved. Because a calibrat ion is included in each sample, no separate calibration sequence was n eeded. Instrument warmup was only a few minutes. The instrument was ve ry robust in field deployments, requiring little maintenance.