采用三波长分光光度法对洋葱中蒜氨酸酶的活性进行了测定,方法有效地消除了由于背景值及光谱吸收峰不对称给定量分析造成的影响,校正了因干扰组分的吸收光谱具有线性吸收所产生的基线倾斜。分别于波长426 nm(λ1)、446 nm(λ2)、506 nm(λ3)处测定吸光度A1、A2和A3,求ΔA=A2-［(λ2-λ3)A1+(λ1-λ2)A3］/(λ1-λ3)。丙酮酸钠的质量浓度在8.8~44.0 mg·L-1之间与ΔA呈线性关系。方法的平均回收率为99.8%,相对标准偏差(n=5)为0.13%。

The activity of alliinase in onion was determined by triple-wavelength spectrophotometry. Not only the interference due to background and asymmetry of absorption peak, but also baseline sloping due to linear absorption of interfering components were eliminated by the proposed method. The absorbance ΔA was calculated by the formula ΔA= A2-［(λ2-λ3)A1+(λ1-λ2)A3］/(λ1-λ3), where values of absorbances, A1, A2 and A3 were measured at the wavelengths of 426 nm (λ1)、 446 nm (λ2)、 506 nm (λ3). Linear relationship between values of ΔA and mass concentration of sodium acetylformate acid was found in the range of 8.8-44.0 mg·L-1. Values of average recovery and RSD (n=5) found were 99.8% and 0.13% respectively.