An experimental study of the measurement of low concentration hydrogen sulfide in an aqueous solution

Abstract

Endogenously generated H₂S has been found not just a toxic substance but may play positive roles, such as the neuromodulator and vasorelaxant in the physiological system since 1990s. Then the precise control of the amount of Hydrogen Sulfide in the animal body raises great interests recently. However, the traditional methods for the Hydrogen Sulfide measurement need a large amount of tissue samples and take a complex procedure; it is impossible to develop any in-vivo real-time approach to measure H₂S along the avenue of these methods. There is a great significance to develop new methods toward the measurement of Hydrogen Sulfide in in-vivo, real time, non- or less invasive manner with high resolution. One general idea to make the measurement less invasive is to take blood as sample – i.e., to measure Hydrogen Sulfide in blood. The study presented in this thesis aimed to conceive of new measurement methods for Hydrogen Sulfide in an aqueous solution along with their experimental verification. Though the blood sample will eventually be taken, the present study focused on an aqueous solution, which is a first step towards the final goal to measure Hydrogen Sulfide in blood. The study conducted a thorough literature review, resulting in the proposal of five methods, including: (i) the Hydrogen Sulfide measurement by Atomic Force Microscopy, (ii) the H₂S measurement by Raman spectroscopy directly, (iii) the Hydrogen Sulfide measurement by Gas Chromatography/Mass Spectroscopy directly (with the static headspace technique), (iv) the Hydrogen Sulfide measurement by Mass Spectroscopy with Carbon Nanotubes, and (v) the Hydrogen Sulfide measurement by Raman spectroscopy with Carbon Nanotubes. The experiments for each of these methods were carried out, and the results were analyzed. Consequently, this study shows that method (v) is very promising to measure low concentration Hydrogen Sulfide in an aqueous solution, especially with the concentration level down to 10 μM and the presence of a linear relationship between the Hydrogen Sulfide concentration and its luminescent intensity.