A cost-efficient and portable sulfide device with in situ integrating gas-permeable porous tube isolation and long path absorbance detection

A cost-efficient and portable device for detecting sulfide at submicromolar level was fabricated by in situ integrating gas-permeable porous tube isolation and long path absorbance detection. The device consisted of a pair of petri dish, having a diametrically strung porous membrane tube in the top cover. The ends of the tube were terminated by a light emitting diode and a photodiode via plugging acrylic optical fiber into the light input/output of tees. Sulfide put in the bottom dish was liberated by addition of diluted acid through a port on the cover. The liberated hydrogen sulfide diffused into the porous membrane tube and reacted with alkaline nitroprusside acceptor in the tube. The color change in the long path porous membrane tube cell was real-time monitored in the transmission mode. The device responded linearly to sulfide concentration over the range of 0.5-150.0 μmol/L with relative standard deviations less than 5% in all cases. The limits of detection for sulfide were within the range 0.2-1.5 μmol/L in aqueous standard and newborn calf serum. The device was successfully applied to the determination of sulfide in human serum samples.