Concentration Determination of Volatile Molecular Iodine and Methyl Iodide

摘要

Appropriate and reliable methods are necessary for routine determination of the concentrations of molecular iodine (I2) and methyl iodide (CH3I), and methods including ultraviolet-visible spectrophotometry on aqueous solution samples for I2 detection and gas chromatography on toluene solution samples for CH3I detection may be used. In this study, we examined the adequacy of the existing spectropholometric method in terms of absorption coefficients at specific light wavelengths for several pH values of the aqueous solutions and selected iodide ion concentrations, and confirmed it finding no dependence of the absorption coefficients on the solution pH and the iodide ion concentration. Additionally, we established methods for CH3I analysis using toluene as a sampling solvent for either capture of CH3I from a gaseous solution or extraction of CH3I from an aqueous solution, and found that using gas-tight syringes, CH3I could be extracted without a significant CH3I loss even at ambient temperature.