Waters xevo g2s q tof mass spectrometer

The LC/MS analysis of carotenoids was carried out using a Waters Xevo G2S Q TOF mass spectrometer (Waters Corporation, Milford, CT, USA) equipped with an Acquity UPLC system. The ESI-TOF/MS spectra were acquired by scanning from m/z 100 to 1500 with a capillary voltage of 3.2 kV, cone voltage of 20 eV, and source temperature of 120 °C. Nitrogen was used as a nebulizing gas at a flow rate of 30 L/h. The MS/MS spectra were measured with a quadrupole-TOF MS/MS instrument with argon as a collision gas at a collision energy of 20 V. The UV-Vis absorption spectra were recorded from 200 to 600 nm using a photodiode-array detector (PDA) (Acquity UPLC PDA eλ Detector, Waters, Milford, MA, USA). An Acquity 1.7 μm BEH UPLC C18 (2.1 id X 100 mm) column (Waters Corporation, Milford, CT, USA) was used as a stationary phase and MeCN/H2O (85:15)–MeCN/MeOH (65:35) (linear gradient 0 to 15 min) as a mobile phase, at a flow rate of 0.4 mL/min for the HPLC system.

The UV–visible (UV–VIS) spectra were recorded with a Hitachi U-2001 (Hitachi High-Technologies Corporation, Tokyo, Japan) in diethyl ether (Et₂O). The positive ion fast atom bombardment mass spectrometry (FAB MS) spectra were recorded using a JEOL JMS-HX 110A mass spectrometer (JEOL, Tokyo, Japan) with m-nitrobenzyl alcohol as a matrix. The positive ion electro spray ionization time of flight mass (ESI-TOF MS) spectra were recorded using a Waters Xevo G2S Q TOF mass spectrometer (Waters Corporation, Milford, CT, USA). The ¹H-NMR (500 MHz) and ¹³C-NMR (500 MHz) spectra were measured with a Varian UNITY INOVA 500 spectrometer (Agilent Technologies, Santa Clara, CA, USA) in CDCl₃. The chemical sifts are expressed in ppm relative to tetramethyl silane (TMS) (δ = 0) as an internal standard for ¹H-NMR and CDCl₃ (δ = 77) as an internal standard for ¹³C-NMR. J values are given in Hz. The CD spectra were recorded in EPA [Et₂O–isopentane–ethanol (5:5:2)] at room temperature with a Jasco J-500C spectropolarimeter (Jasco corporation, Tokyo, Japan). Preparative high-performance liquid chromatography (HPLC) was performed on a Shimadzu LC-6AD with a Shimadzu SPD-6AV spectrophotometer (Shimadzu Corporation, Kyoto, Japan) set at 450 nm. The column used was a 250mmX10mm i.d. 10 μm Cosmosil 5SL-II and 5C18 II (Nacalai tesque, Kyoto, Japan).