应用高效液相色谱法(HPLC)测定了乳清粉和黄油中过氧化苯甲酰的含量。对含脂肪较低的样品,可直接加入乙腈进行提取,经振摇和离心后取上清液,用0.45 μm滤膜过滤,滤液用于HPLC分析。对含脂肪较高的样品,须先用正己烷脱脂,然后用经正己烷饱和的乙腈提取3次,合并提取液经0.45 μm滤膜过滤后供HPLC分析。采用Agilent TC C18色谱柱及由甲醇-水(65+35)混合液作为流动相进行分离,并在236 nm波长处进行紫外检测。过氧化苯甲酰的质量浓度在0.1~1.0 mg·L-1范围内与其相应的峰面积呈线性关系。方法的测定下限(10S/N)为1.0 mg·kg-1。以乳清粉及黄油样品为基体,用标准加入法在3个浓度水平(1,5,10 mg·kg-1)上对方法进行回收试验,测得回收率在96.6%~104.0%之间,测定值的相对标准偏差(n=6)均小于7.0%。

HPLC was applied to the determination of benzoyl peroxide in whey powder and butter. Samples, with low fat-content were extracted directly with acetonitrile. After shaking and centrafuging, the supernatant was filtered with 0.45 μm filtering membrane and the filtrate was used for HPLC analysis. Samples, with high fat-content, were first defatted with n-hexane, and then extracted thrice with acetonitrile (which has been saturated with n-hexane). The acetonitrile layers were combined, filtered and used for HPLC analysis. The Agilent TC C18 chromatographic column and the mobile phase of mixture of methanol and water (65+35) were used for the separation. UV-detection at the wavelength of 236 nm was adopted in measurements. Linear relationship between values of peak area and mass concentration of benzoyl peroxide was obtained in the range from 0.1 to 1.0 mg·L-1. Lower limit of determination (10S/N) was found at 1.0 mg·kg-1. Using sample of whey powder and butter as matrixes, recovery was tested by addition of standard solution of benzoyl peroxide at 3 concentration levels (1, 5, 10 mg·kg-1), values of recovery found were in the range of 96.6%-104.0% with RSD′s (n=6) less than 7.0%.