Proficiency with instrumental analysis via GC–MS is an important skill for chemistry students. The application of analytical techniques and fundamental theoretical principles to real-world problems can be valuable learning exercises for undergraduates which can also improve their analytical thinking skills. Xylitol is generally considered safe for human consumption and is frequently used in sugar-free gum; however, it is extremely toxic to dogs. In this laboratory experiment, upper-level undergraduate chemistry students extract xylitol from both fresh and chewed gum sticks followed by direct aqueous injection GC–MS analysis. Students learn the proper steps and techniques required for sample extraction and preparation and GC–MS analysis, and they determine concentrations of xylitol present in gum samples. Identification and quantification of the chemical components in gum extract occurs via GC–MS analysis; however, other GC detectors could be used. Students also compare external and internal standard calibration methods for xylitol quantification. Upon quantification of xylitol in chewed and unchewed gum samples, students are able to calculate the level of hazard for dogs upon ingestion.

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直接水注射GC-MS测定无糖口香糖中的木糖醇：化学专业学生的实验室实验

通过GC-MS进行仪器分析的能力是化学专业学生的一项重要技能。将分析技术和基本理论原理应用于现实世界中的问题，对于本科生来说是有价值的学习练习，也可以提高他们的分析思维能力。木糖醇通常被认为对人类食用是安全的，并且经常用于无糖口香糖中。但是，它对狗有剧毒。在此实验室实验中，高年级化学专业的学生从新鲜和咀嚼的口香糖棒中提取木糖醇，然后直接进行水进样GC-MS分析。学生学习样品提取和制备以及GC-MS分析所需的正确步骤和技术，并确定胶质样品中木糖醇的浓度。口香糖提取物中化学成分的鉴定和定量通过GC-MS分析进行；但是，可以使用其他GC检测器。学生还将比较木糖醇定量的外部和内部标准校准方法。通过定量咀嚼和未咀嚼的口香糖样品中的木糖醇含量，学生可以计算出摄入后对狗的危害程度。