title: Fluorometric field instrument for continuous measurement of atmospheric hydrogen sulfide.
abstract: A sensitive (limit of detection approximately <100 pptv at S/N = 3), fully automated, portable (32 x 25 x 38 cm, 4.5 kg) instrument has been designed for continuous field measurement of atmospheric hydrogen sulfide. Air is sampled by a PTFE membrane-based diffusion scrubber and collected into an aLkaline fluorescein mercuric acetate (FMA) solution flowing under a controlled and constant pneumatic pressure. The collected sulfide quenches the fluorescence that is measured with a miniature blue LED photodiode-based fluorescence detector. Acquisition and interpretation of signal and all flow control are carried out via a mininotebook personal computer (PC) using custom software written in HP-VEE. The instrument provides for self-calibration and zero functions using an on-board permeation tube enclosed in a thermostated block, at any preprogrammed desired interval. During sampling, the computed H2S concentration is stored every 2 min. The complete system, including the PC, is operated in the field by a 12-V marine battery. The system was field tested near oil field operations in West Texas and showed good correlations with a concurrently operated lead acetate tape-based commercial sampler, with a response speed and time resolution much better than that of the latter instrument.
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University, Lubbock 79409-1061, USA.
authors.forename: K
authors.initials: K
authors.lastname: Toda
authors.forename: P K
authors.initials: PK
authors.lastname: Dasgupta
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: G A
authors.initials: GA
authors.lastname: Tarver
authors.forename: G M
authors.initials: GM
authors.lastname: Zarus
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D006862:Hydrogen Sulfide / Q000032:analysis*; D007202:Indicators and Reagents; D008567:Membranes, Artificial; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence
chemical_list: D000393:Air Pollutants; D007202:Indicators and Reagents; D008567:Membranes, Artificial; D006862:Hydrogen Sulfide