[Separation of two isomers in the products of condensation reaction with trimethoxybenzaldehyde as raw material and quick determination of the concentration of its intermediates by high performance liquid chromatography].

The content ratio of the two isomers in the products of condensation reaction with trimethoxybenzaldehyde as raw material is the key factor to improve the productivity of trimethoprim(TMP). A quantitative method using Nova-Pak C18 column (3.9 mm i.d. x 150 mm, 4 microns) and tetrahydrofuran(THF)-water (30:70, V/V) as mobile phase with flow rate of 1.0 mL/min and UV 320 nm detector was established. A good linearity was obtained in the concentration range of 0.01 mg.L-1-10 mg.L-1. The detectable limits of trimethoxybenzaldehyde and alpha-(3,4,5-trimethoxy-benzal)-beta-methoxy-propionitrile were 2.0 micrograms/L and 1.0 microgram/L respectively. The method has been used to analyze real samples with satisfactory results.