IC Determination of Indol-3-acetic Acid and Indol-3-butyric Acid in Fruit and Vegetable

The sample of fruit or vegetable (5.00 g) was extracted ultrasonically with (45 mL) of a mixture of CH₃CN and 35 mmol·L^-1 NaOH solution (10+90), and the extract was then purified on C₁₈ SPE colunm. The purified extract was separated by IC, using AS11 column (4 mm×250 mm) as stationary phase and the same mixture of CH₃CN and NaOH solution mentioned above as mobile phase. UV detector was used in the determination. Linear relationships between values of mass concentration of indol-3-acetic acid and indol-3-butyric acid were kept in the same range of 0.05-10 g·L^-1, with detection limits (3S/N) of 0.009, 0.012 g·L^-1 respectively. Precision of the method was tested at the concentration level of 10 g·L^-1 indol-3-acetic acid and indol-3-butyric acid mixed standard solution for 6 determination, RSD's found from the peak area values were 0.14% and 1.4% respectively. Tests for recovery were made by standard addition method at the concentration levels of 0.50, 2.0, 10 g·L^-1, giving values of recovery in the range of 77.1%-104%.