Figure 1.

HPLC–ELSD chromatogram of a standard mixed solution. 1—GSH (20 µg ml⁻¹), 2—PC₂ (20 µg ml⁻¹), 3—PC₃ (20 µg ml⁻¹), 4—PC₄ (20 µg ml⁻¹), 5—PC₅ (20 µg ml⁻¹), 6—PC₆ (20 µg ml⁻¹). The gradient elution process was: 10%A to 30%A (0–10 min), 30%A to 100%A (10–15 min), 100%A to 10%A (15–20 min), 10%A (20–25 min) at a flow rate of 0.8 ml min⁻¹; column temperature: 30°C; temperature in the drift tube: 50°C; flow rate of the carrier gas: 1.5 l min⁻¹; sample injection volume: 10 µl.