Column length, isocratic liquid chromatography

Quantitation of 1. Quantitation was performed by high performance liquid chromatography using a Hewlett Packard 1050 system. One mg of root exudates were dissolved in I mL of acetonitrile. Components of the root exudates was separated on an Alltech EPS CIS column 100 A 3p (ISO mm length x 4.5 mm internal diameter). The mobile phase was eluted at a flow rate of 2 mL/min as follows (solvent A is 2.5% acetic acid in water, solvent B is acetonitrile) 0-15 min 45% A / 55% B isocratic 15-22 min linear gradient from 55% to 100% B 22-25 min 100%B 25-26 min 100% to 55% B 26-30 min 45% A / 55% B isocratic. The peaks were monitored at X280 nm, and the volume of injection was 20 pL. Quantitation was based on a calibration curve of an external standard of purified 1. 

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