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into a 20-mL headspace vial to which 5 mL of ethyl acetate was added to extract the fumigants. The headspace vial was crimp-sealed and vortexed for ≈30 s; then, it was frozen (−10 °C) for later gas chromatography–mass spectrometry (GCMS) analyses

with the root. The root was dried using filter paper and then extracted with ethyl acetate. The red extractant was transferred into the volumetric flask to reach 10 mL by adding ethyl acetate. The absorbance of the extract at 485 nm was recorded. Root

International Ltd., Maidstone, Kent, England) at room temperature. The resulting mixtures were pooled and evaporated to the aqueous phase, which was subsequently adjusted to pH 10 with 1 m KOH and partitioned against 100% ethyl acetate. After centrifuging the

acetate (7:0.96:0.04:2, mobile phase B) was pumped for 1 min. Finally, acetonitrile:methanol:water:ethyl acetate (7:0.96:0.04:8, mobile phase C) was pumped until all the components were eluted. The doubly distilled water was filtered with a HPLC solvent

, ethyl acetate, formic acid) were analytical-grade reagents, whereas methanol for chromatographic analyses was HPLC-grade; all the solvents were obtained from Merck (Darmstadt, Germany). Formic acid to be used as a mobile phase additive was of liquid

extracted twice with 15 mL n-hexane:ethyl acetate (9:1). The organic phase was collected, evaporated by Rotavapor (IKA, Labortechnik, Staufen, Germany), and the dry residue was dissolved in 1 mL 98% (v/v) methanol. A sample volume of 20 mL was separated by

vigorously. C-KODA was extracted using ethyl acetate, and isolated with high-performance liquid chromatography (NANOSPACE SI-1, Shiseido, Tokyo, Japan) using a CAPCELL PAK C 18 column (Shiseido). The mobile phase was 50% CH 3 CN in 0.05% trifluoroacetic acid

with internal standards of [ 2 H 2 ]-ABA and reduced to aqueous phase. The aqueous phase was extracted with ethyl acetate at pH 3, then with potassium phosphate buffer at pH 8.5, again into ethyl acetate at pH 3, and further purified on C 18 Sep

) , but with slight modifications. Mobile phase eluents consisted of A (80% methanol/20% water) and B (100% ethyl acetate). The total run time was 34 min at a flow rate of 1.2 mL·min −1 . The injection volume was 20 μL for the analysis. The column used was

hexane until colorless. Samples of the hexane extract were dried in a SpeedVac™ (Thermo Savant, Holbrook, NY) and resuspended to an appropriate concentration in a small volume of ethyl acetate and then diluted with the mobile phase. Sample extracts were