Agilent 7683b autosampler

Each FAME sample (1 μL) was injected into the Agilent 7890A GC with an Agilent 7683B autosampler (Agilent, Atlanta, GA, USA) with a split ratio of 25 and separated in a 30 m × 0.25 mm I.D. fused-silica capillary column coated with 0.25 μm CP-SIL 8 CB Low Bleed (Varian Inc., Palo Alto, CA, USA). The injector temperature was 230 °C. The helium gas flow rate through the column was 1.0 mL/min. The temperature program was as follows: starting temperature 80 °C, maintained for 2 min, followed by an increase to 320 °C at 15 °C/min and a 10 min hold at 320 °C. The transfer line and ion-source temperatures were 250 and 200 °C, respectively. The scanned mass range was 85–600 m/z, and the detector voltage was set at 1700 V.

A LECO Pegasus 4D GC*GC–TOF/MS instrument (LECO Corporation, St. Joseph, MI, USA) equipped with an Agilent 6890 N (Agilent, PaloAlto, CA, USA) was used in analyzing the extracts of these tea samples. The first dimension (1D) column was a DB-5MS column of 30 m × 250 μm × 0.25 μm and the second dimension (2D) was a DB-17HT column of 10 m × 100 μm × 0.10 μm (J&W Scientific, Folsom, CA, USA). The temperatures of the GC inlet and transfer line were set at 280 °C and 270 °C, respectively. The carrier gas was 99.9995 % high purity helium at a constant pressure mode. The pressure at the head of the column was 200kPa. Cryogenic modulation was used with a modulation period of 5.0 s. An Agilent 7683B autosampler was used with an injection volume of 1.0 μl in splitless mode. The oven temperature of the first column was held at 60 °C for 3 min, and then ramped to 280 °C (4 °C/min), and held for 5 min at the last temperature. The oven temperature of the second column was initially held at 70 °C for 3 min, and then followed the same program of the first column. The total analysis time was 40.75 min.