Nunome Yoko, Kodama Kenji, Ueki Yasuaki, Yoshiie Ryo, Naruse Ichiro, Wagatsuma Kazuaki
Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, 739-8521, Japan.
X-ray Instrument Division, Rigaku Corporation, 14-8 Akaoji, Takatsuki, Osaka, 569-1146, Japan.
Talanta. 2019 Nov 1;204:310-319. doi: 10.1016/j.talanta.2019.05.115. Epub 2019 Jun 4.
The ionization source based on glow discharge plasma using ambient air is driven by a pulsed direct-current voltage for soft plasma ionization (SPI). The novelty of this work is that molecular ions [M+13] related to the analyte species (M), which may be formed by numerous oxidation, can be dominantly detected as a base peak with little or no fragmentation of them in an air plasma at a pressure of several kPa. The unique ion [M+13] was assigned to the oxidation product, [M+O-3H], which was confirmed as a deuterated ion [M+O-3D] ([M+10]) by using a deuterated solvent. The ionization reactions were suggested that the product ion [M+O-3H] may arise from hydride abstraction reaction of M with O, dehydrogenation reaction of [M-H] and subsequently oxidation reaction of [M-3H] with O. n-Alkane mixtures was also measured to evaluate the intermolecular interaction in this system. The limits of detection (LOD) were in the range of 0.126-1.68 ppmv and the relative standard deviation (RSD) for repeatability was approximately 10.0% at the lowest concentration. To our knowledge, this is the first report demonstrating that the spectrum pattern of saturated hydrocarbons could be directly determined without any complicated fragmentation.
