文章用比值—导数光谱法测定香草醛的含量。实验结果表明,香草醛木素溶液在pH≤7时香草醛在230 nm处有吸收,在pH>7时在248 nm处有吸收。根据不同pH值和不同浓度条件下香草醛木素溶液的比值-导数光谱,说明在230 nm处的光谱信号在pH≤7不受pH值影响,248 nm处的光谱信号在pH>7不受pH值影响。在230 nm和248 nm处的光谱信号对浓度的变化较为敏感,在此两处吸收值可用于香草醛的测定。 The article uses ratio - derivative spectrometry to determine the content of vanillin. The experimental results show that vanillin solution has absorption at 230 nm at pH≤7 and absorption at 248 nm at pH> 7. According to the ratio - derivative spectra of vanillin lignin solution under different pH values ​​and different concentrations, the spectral signal at 230 nm is not affected by pH at pH≤7 and the spectral signal at 248 nm is not affected by pH> 7 pH effect. Spectral signals at 230 nm and 248 nm are more sensitive to changes in concentration, where the two absorbance values ​​are used for the determination of vanillin.