High performance liquid chromatography (HPLC) was developed for the quantitative analysis of protocatechuic acid (PA) in Spatholobi Caulis (the stem of Suberect spatholobus Dunn.). The preparation method of sample solution was established by optimizing the extraction solvents

methods

times and the sizes of the crude drug. The sample solutions were analyzed using a C

18

column ( 250 × 4.6 mm，5μm) with CH3CN-φ=0.5% HAc (volumic ratio

10:90) as mobile phase and detected at 260 nm with a flow rate of 1.0 mL·min

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. The crude drug was extracted by boiling water for three times and 1.5 h for each time. The obtained aqueous solution was concentrated and followed by extracted with ethyl acetate for four times. The ethyl acetate layer was concentrated to dryness

and was resolved in methanol-water (volumic ratio

1:1) to give the sample solution previous to HPLC analysis. After systematic method evaluation

the results showed that the linear range was 8.56～214 μg·mL

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 with correlation coefficient R

2

of 0.999 7; and the average recovery rate was 99.2% with RSD of 2.8%. The contents of PA in marketsold seven batches of Spatholobi Caulis were determined to be in the range of 65.81～122.35 μg·g

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. The established method was accurate and repeatable

which could be used for the quality control of Spatholobi Caulis.