Isotope Ratio by HRGC-MS of Citrus junos Tanaka (Yuzu) Essential Oils: m/z 137/136 of Terpene Hydrocarbons

MS Fragment Isotope Ratio Analysis for Evaluation of Citrus Essential Oils by HRGC-MS

“…The MS fragment ratio was measured using the isotope ratio measurement method described in previous papers. [10][11][12] Selective ion monitoring (SIM) of GC-MS was done in order to estimate the intensities of ion peaks of each major MS fragments (m=z ¼ m) and of its þ1 fragment peaks (m=z ¼ m þ 1). The MS fragment ratio of each peak was calculated using the following equation:…”

“…10,11) Furthermore, it was statistically demonstrated that this method was not affected by such variations as sampling years, trees, and fruiting positions as long as the plants were grown under set conditions. 12) However, it is often difficult to measure the isotope ratio by ordinary GC-MS when the molecular ion peak is very small or not detected.…”

Effects of Several Variable Factors on the Isotope Ratio by HRGC-MS

“…The statistical treatments, t-test and sign test, were done as well as described before. 4,10) A sign test was applied to the following evaluation. The Irs of ten monoterpene hydrocarbons in the CPOs from each of the six fruiting positions of three trees were measured in triplicate in an individual year.…”

“…[1][2][3] Recently, many sensational articles have been reported on dishonest designations of raw foods, since the JAS (Japanese Agricultural Standards) were revised on July 2000. The authors 4) have developed a specific and convenient method for characterization of yuzu (Citrus junos Tanaka) fruits produced in different districts by the isotope ratio of monoterpene hydrocarbons with HRGC-MS. This method will be applicable to several cases such as differentiation of the quality, evaluation of genuineness of vegetable products from various producing districts, and classification of the species.…”

“…All the data obtained on each monoterpene hydrocarbon were first treated with the t-test between 2001 and 2002, and then the resulting data were analyzed by a sign test. 4) The y To whom correspondence should be addressed. Tel: +81-88-864-5184; Fax: +81-88-864-5200; E-mail: sawamura@cc.kochi-u.ac.jp…”