Fig. 2

Effect of pH on IBCF derivatization (x-axis = pH, y-axis = peak height) and GC elution of T, U, C, A, and G from the column HP-5 (30 m × 0.32 mm id) at column temperature 100 °C for 1 min with a programmed heating rate at 30 °C min⁻¹ up to 280 °C and held at maximum temperature for 2 min. The nitrogen flow rate was 1.5 mL min⁻¹ with split ratio 10:1. The detector and injector temperatures were 290 °C. The flow rate for FID was set fixed for nitrogen as make-up gas 45 mL min⁻¹, air 450 mL min⁻¹, and hydrogen 40 mL min⁻¹