Much of analytical chemistry involves the analysis of complex mixtures, where careful attention to sample preparation and method selectivity is required to avoid interferents and obtain accurate data. As this type of analysis is very different from simple colorimetric analysis that most students are exposed to in general chemistry, this laboratory exercise was developed to help students discover the importance of sample preparation, specifically extraction and pH adjustment, for quantifying the “bitterness” derived from iso-α-acid content in beer. In this exercise, students deviate from the standard UV–vis absorbance method and compare calculated bitterness (i.e., iso-α-acid concentration) to the beer manufacturer’s reported bitterness, helping them clarify how the standard method works and why the beer must be “cleaned up” prior to analysis.

中文翻译：

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量化啤酒苦味：样品前处理影响的调查

许多分析化学都涉及复杂混合物的分析，在这种情况下，需要仔细注意样品的制备和方法的选择性，以避免产生干扰物并获得准确的数据。由于这种类型的分析与大多数学生在常规化学中所接触到的简单比色分析有很大不同，因此开发本实验室练习是为了帮助学生发现样品制备的重要性，特别是提取和pH调节，以量化衍生的“苦味”啤酒中的异α-酸含量。在本练习中，学生将偏离标准的紫外可见吸收法，并将计算出的苦味（即，异α-酸浓度）与啤酒制造商报告的苦味进行比较，以帮助他们阐明标准方法的工作原理以及为什么啤酒必须是“清理”。