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Inorganic polysulfides' quantitation by methyl iodide derivatization: dimethylpolysulfide formation potential
1The Laboratory of Environmental Chemistry, Casali Institute of Applied Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Summary
Inorganic polysulfides are challenging to measure directly. Methylation with methyl iodide offers a promising method, revealing continuous polysulfide formation driven by the methylation process itself.
Area of Science:
- Environmental Chemistry
- Analytical Chemistry
Background:
- Inorganic polysulfides are key intermediates in forming volatile sulfur compounds.
- Directly quantifying inorganic polysulfides in natural systems, especially under oxic conditions, is currently infeasible.
Purpose of the Study:
- To evaluate the method of polysulfide quantification using derivatization with methyl iodide.
- To investigate the conversion efficiency of inorganic polysulfides to dimethylpolysulfides.
Main Methods:
- Methylation of inorganic polysulfides using methyl iodide.
- Analysis of the resulting organic polysulfides.
Main Results:
- Near 100% conversion of polysulfide salts to organic polysulfides at low concentrations.
- Low recovery at high concentrations or when solubility limits are exceeded.
- Observed polysulfide recovery exceeding 1,000% at very low dissolved concentrations, attributed to concurrent polysulfide formation.
Conclusions:
- Methylation with methyl iodide is a valuable method for studying polysulfide formation in natural systems.
- The methylation process can drive continuous inorganic polysulfide formation from hydrogen sulfide and sulfur precipitate.
- The method shows high sensitivity at low concentrations but requires careful consideration of solubility and precursor concentrations at higher levels.
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