为提高质谱法测定蛋白质的准确性，对酶解条件的优化和选择并建立最佳条件，以期提高回收率。设计了7种酶解方法进行了比较，并引入豆浆作为阴性基质。其中直接酶解法被选为最佳方法，其操作操作过程如下：取1 g豆浆粉溶于10 mL的50 mmol·L^-1三羟甲基氨基甲烷-盐酸缓冲溶液中制成豆浆提取液，取200 nmol·L^-1 β-酪蛋白溶液200 μL，加入豆浆提取液300 μL，再加10 μg质谱级胰蛋白酶，混匀后于37℃恒温酶解16 h，加入10%（体积分数）甲酸溶液10 μL，终止反应，加水定容至1.0 mL，高速离心10 min，取上清液进样，按仪器工作条件测定VLPVPQK特征肽段的峰面积。此方法的平均酶解效率为106%，相对标准偏差（n=5）为5.1%。方法中选择酶的加入量w_酶与β-酪蛋白量w_{β-酪蛋白量}之比为1∶20。在方法的优化过程中不建议进行还原和烷基化步骤。

Improving recovery of MS determination of protein is one of the factors to raise the accuracy of the method, hence a study on optimization and establishment of optimum conditions for enzymolysis is of utmost importance. Seven methods for enzymolysis were designed and studied comparatively. Soy-bean milk was used as negetive matrix in the testing. The direct enzymolysis was found to be the best one among the 7 enzymolytic methods proposed, and its procedure was given below:1 g of soybean milk powder is dissolved in 10 mL of 50 mmol·L^-1 Tris-HCl buffer solution to give the soy-bean milk extract. 200 μL of 200 nmol·L^-1 β-casein solution are added to 300 μL of the soy-bean milk extract together with 10 μg of trypsin (MS-grade). After mixing, the solution was enzymolyzed at 37℃ for 16 h. At the end of enzymolysis, 10 μL of 10% (φ) formic acid solution were added to stop the reaction. Volume of the solution was made up to 1.0 mL. The solution is contrifuged at high rate for 10 min. The supernatant is used for UPLC-MS/MS analysis to take down the peak-area of the characteristic peptide segment of VLPVPQK. Efficiency of enzymolysis found for this method was 106% with RSD (n=5) of 5.1%. Optimal ratio of mass of trypsin added (w_trypsin) to mass of β-casein present was found to be 1 to 20. Reduction and alkylation were not applied in the optimization of the method proposed.