Atmospheric Pressure Photoionization Mass Spectrometry (Arw-APPI / MS) Using A Low-Pressure Mercury Vapor Lamp Installed In A Hydrous Argon Gas Stream

Mochida Y

Published on: 2023-02-01

Abstract

Low-pressure mercury lamp-atmospheric pressure photoionization mass spectrometry (LPML-APPI / MS) was developed, in which organic compounds are ionized by excited argon or hydronium ions produced by a low-pressure mercury lamp emitting light in an anhydrous or hydrated argon gas stream. That is, it is not the known direct ionization of the enclosed rare gas (Kr, Xe, Ne) by light using the excitation light, but the excitation light excites the hydrated argon gas flowing outside the lamp. Furthermore, the expansion of the hydronium ion group produced can be controlled by the water content. Since this method is used in argon gas which does not contain oxygen, ozone causing environmental deterioration does not occur. Ionization of the atmospheric background with water-free argon gas produced only protonated molecules of dimmer of hydronium ions and water. Water clusters of three or more molecules did not appear. When water was added to the argon gas, cluster ions of water appeared, and as the amount of water increased, the group of ions appeared to a high region. When it was further increased, it moved to the higher region side. One or two protonated molecules of water molecules did not appear in the helium gas used in DART. However, more than 3 cluster ions were observed. Nitrogen gas had no effect. The appearance of protonated methyl alcohol and ethyl alcohol required water. And, along with the increase in water content alcohol cluster ion groups appeared and with further increase they were accompanied by water addition ions. This method, which can use water, can control the decomposition of thermo-sensitive peroxides. For lauroyl peroxide, protonated molecules appeared in the presence of water in the gas, and cleaved site ions appeared in its absence. If water clusters are prominent over a high range of masses, the addition of reagents with high proton affinity can cause simplified protonated molecules to emerge. In particular, the effects of lower amines were great.