Abstract The use of organic acids (e.g. acetic acid and gluconic acid) as additives during protease production is regarded as one of the simplest alternatives to increase enzyme stability and activity in many industrial processes. However, no methods have been described for the determination of organic acids in proteases and their contents have not been established yet. In this work, a novel, rapid and simple method for the determination of organic acids in proteolytic enzymes by capillary electrophoresis (CE) with indirect ultraviolet (UV) detection has been developed. Under the optimized conditions, the method was validated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ) and intra-day and inter-day repeatability. Later, a sample pretreatment based on a hydroalcoholic microextraction was carefully optimized to obtain good recovery and repeatability and determine acetic and gluconic acids in a commercial protease sample. The complete procedure was validated using the standard-addition calibration method, finding matrix effects on the studied compounds. Finally, acetic acid and gluconic acid were quantified at 80 mg/Kg (0.0080% (m/m)) and 69 mg/Kg (0.0069% (m/m)) in the protease sample, respectively.

中文翻译：

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毛细管电泳-间接紫外检测法测定蛋白水解酶中有机酸的快速简便方法

摘要 在蛋白酶生产过程中使用有机酸（例如乙酸和葡糖酸）作为添加剂被认为是在许多工业过程中提高酶稳定性和活性的最简单的替代方法之一。然而，没有描述测定蛋白酶中有机酸的方法，其含量也尚未确定。在这项工作中，开发了一种通过毛细管电泳 (CE) 和间接紫外 (UV) 检测来测定蛋白水解酶中有机酸的新型、快速和简单的方法。在优化的条件下，该方法在线性、检测限 (LOD)、定量限 (LOQ) 和日内和日间重复性方面得到验证。之后，基于水醇微萃取的样品预处理经过精心优化，以获得良好的回收率和可重复性，并测定商业蛋白酶样品中的乙酸和葡萄糖酸。使用标准加入校准方法验证了整个过程，发现了对研究化合物的基质效应。最后，蛋白酶样品中乙酸和葡萄糖酸的含量分别为 80 mg/Kg (0.0080% (m/m)) 和 69 mg/Kg (0.0069% (m/m))。