Abstract
A porous cellulose tape coated with silica gel as the absorbent and impregnated with a processing solution that includes silver perchlorate, p-toluenesulfonic acid, glycerin and methanol is a highly sensitive means of detecting hydrogen sulfide and is stable upon exposure to light. Hydrogen sulfide, absorbed on the surface of the tape, reacted with silver perchlorate to form a stain (silver sulfide), the intensity of which could be measured quantitatively by an optical system to determine the concentration of hydrogen sulfide. A linear relation was obtained between sampling time and relative intensity in the range of 550 ppb of hydrogen sulfide at a constant flow rate of sampling gas. The detection limit (signal-to-noise ratio=3) was 2 ppb for hydrogen sulfide with a sampling time of 5 min and flow rate of 350 ml/min. The sensitivity of this tape was 2.5 times as high as that previously reported. This method is not greatly affected by other gases except for hydride gases such as phosphine.
