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Kumquats (Fortunella margarita Swingle) cultivated in Taiwan are eaten raw or made into candied fruit or fruit tea. For the experiments described in this paper, essential oils were obtained from kumquat peels or whole fruit by cold pressing, steam distillation or heating in water at 90 °C for 15 min followed by steam distillation. The volatile components contained in the essential oils were identified by direct injection (DI) or headspace-solid phase microextraction (HS-SPME) coupled with gas chromatography (GC). A total of 43 compounds were identified, of which 37 were verified by DI/GC and 31 by HS-SPME/GC. Hot water heating increased the yields of essential oils from both peels and whole fruit. The principal constituents of the oils were similar except for the minor compounds, including linalool, terpinen-4-ol and α-terpineol, the levels of which increased after steam distillation. The whole fruit also contained higher levels of terpene alcohols.

Di-isononyl phthalate esters (DINPs) are endocrine-disrupting chemicals and have replaced di(2-ethylhexyl) phthalate (DEHP) as the major plasticizer for poly(vinyl chloride) (PVC) products in recent years. Exposure marker discovery of DINPs is crucial, because of their high potential for human exposure and toxicity. Here, we propose an alternative approach for tracing signals derived from stable isotope-labeled precursors with varied labeling ratios to efficiently filter probable metabolite signals. The statistical process, which involves a signal mining algorithm with isotope tracing (SMAIT), has effectively filtered 13 probable DINP metabolite signals out of the 8867 peaks in the LC-MS data obtained from incubated stable isotope-labeled precursors with liver enzymes. Seven of the 13 probable metabolite signals were confirmed as DINP structure-related metabolites by preliminary MS/MS analyses. These 7 structure-related metabolite signals were validated as effective DINP exposure markers, using urine samples collected from DINP-administered rats without time-consuming comprehensive structure identification. We propose that the 7 identified possible DINP metabolite signals of m/z 279.1, 293.1, 305.1, 307.1, 321.1, 365.1, and 375.1 are potential markers for DINP exposure and should be investigated further. The integrated approach described here can efficiently, and systematically, filter probable metabolite signals from a complex LC-MS dataset for toxic exposure marker discovery. It is a relatively low-cost/rapid workflow for exposure marker discovery.

Volatile constituents of calamondin peel or whole fruit were obtained by cold pressing, steam distillation, or hot water treatment at 90°C for 15 minutes followed by steam distillation. The volatile components of the essential oils were identified by direct injection coupled with gas chromatography–flame ionization detector. A total of 54 compounds were identified, including 13 monoterpenes, 7 monoterpene alcohols, 1 monoterpene oxide, 4 monoterpene aldehydes, 2 monoterpene ketones, 4 monoterpene esters, 12 sesquiterpenes, 3 aliphatic alcohols, 6 aliphatic aldehydes, and 2 aliphatic esters, with limonene and β-myrcene as the major compounds. The results showed that hot water treatment increased the yields of essential oils from both peel and whole fruit. The relative percentage of the principle constituents in the various prepared essential oils were similar, except for some minor compounds, including linalool, terpinen-4-ol, α-terpineol, and carvone, the content of which were boosted by steam distillation. Whole fruit contained higher levels of monoterpene alcohols than peel did.