Formation of Metal-Adducted Analyte Ions by Flame-Induced Atmospheric Pressure Chemical Ionization Mass Spectrometry

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• 作者：Sy-Chyi Cheng ; Chin-Hsiung Wang ; Jentaie Shiea
• 刊名：Analytical Chemistry
• 出版年：2016
• 出版时间：May 17, 2016
• 年：2016
• 卷：88
• 期：10
• 页码：5159-5165
• 全文大小：437K
• 年卷期：0
• ISSN：1520-6882

文摘

A flame-induced atmospheric pressure chemical ionization (FAPCI) source, consisting of a miniflame, nebulizer, and heated tube, was developed to ionize analytes. The ionization was performed by reacting analytes with a charged species generated in a flame. A stainless steel needle deposited with saturated alkali chloride solution was introduced into the mini oxyacetylene flame to generate alkali ions, which were reacted with analytes (M) generated in a heated nebulizer. The alkali-adducted 18-crown-6 ether ions, including (M + Li)⁺, (M + Na)⁺, (M + K)⁺, (M + Rb)⁺, and (M + Cs)⁺, were successfully detected on the FAPCI mass spectra when the corresponding alkali chloride solutions were separately introduced to the flame. When an alkali chloride mixture was introduced, all alkali-adducted analyte ions were simultaneously detected. Their intensity order was as follows: (M + Cs)⁺ > (M + Rb)⁺ > (M + K)⁺ > (M + Na)⁺ > (M + Li)⁺, and this trend agreed with the lattice energies of alkali chlorides. Besides alkali ions, other transition metal ions such as Ni⁺, Cu⁺, and Ag⁺ were generated in a flame for analyte ionization. Other than metal ions, the reactive species generated in the fossil fuel flame could also be used to ionize analytes, which formed protonated analyte ions (M + H)⁺ in positive ion mode and deprotonated analyte ions (M – H)⁻ in negative ion mode.