Measurement of Parts per Million Level Gaseous Concentration of Hydrogen Sulfide by Ultraviolet Spectroscopy using 1,1,1,5,5,5-Hexafluoropentan-2,4-dione as a Derivative by Reaction of Cu(hfac)(1,5-Cyclooctadiene)

Hydrogen sulfide reacts rapidly and quantitatively at ppm levels with cycloocta-1,5-diene-1,1,1,1,5,5,5-hexafluoropentan-2,4-dionatocopper(I) (Cu(hfac)(COD)) to yield 1, 1, 1,5,5,5-hexafluoropentan-2,4-dione (Hhfac) having a strong ultraviolet absorption at 268 run, and which can be used without interference as a derivative in the continuous, fast online spectroscopic determination of the H(2)S concentration. The analytical method has excellent selectivity and can be used in the presence of N(2), H(2), CO, COS, SO(2), moist air, CH(3)OH, C(2)H(4), C(6)H(6), and light alkanes including fuel gases. Using a standard spectrometer, the level of detection is about 10 ppb. Concentrations down to 1 ppm H(2)S can be analyzed readily, usually with an error in the range 0 to -7% dependent largely on the sorption characteristics of the apparatus. These are systematic errors due to adsorption; however, the analytical apparatus was very stable, and relative standard deviations as low as 0.1% of the mean can be obtained. The method can also be applied to the analysis of methanethiol.