Mistry Sabyasachy, Wenthold Paul G
The Department of Chemistry and Biochemistry, Purdue University, 560 Oval Drive, West Lafayette, IN, 47907, USA.
J Mass Spectrom. 2018 Oct;53(10):947-953. doi: 10.1002/jms.4261. Epub 2018 Aug 15.
This paper describes a new method for detecting phenols, by reaction with Gibbs reagent to form indophenols, followed by mass spectrometric detection. Unlike the standard Gibbs reaction, which uses a colorometric approach, the use of mass spectrometry allows for simultaneous detection of differently substituted phenols. The procedure is demonstrated to work for a large variety of phenols without para-substitution. With para-substituted phenols, Gibbs products are still often observed, but the specific product depends on the substituent. For para groups with high electronegativity, such as methoxy or halogens, the reaction proceeds by displacement of the substituent. For groups with lower electronegativity, such as amino or alkyl groups, Gibbs products are observed that retain the substituent, indicating that the reaction occurs at the ortho or meta position. In mixtures of phenols, the relative intensities of the Gibbs products are proportional to the relative concentrations, and concentrations as low as 1 μmol/L can be detected. The method is applied to the qualitative analysis of commercial liquid smoke, and it is found that hickory and mesquite flavors have significantly different phenolic composition.
本文描述了一种检测酚类的新方法，即通过与吉布斯试剂反应形成靛酚，然后进行质谱检测。与使用比色法的标准吉布斯反应不同，质谱法的使用允许同时检测不同取代的酚类。该方法已被证明适用于多种无对位取代的酚类。对于有对位取代的酚类，仍经常观察到吉布斯产物，但具体产物取决于取代基。对于具有高电负性的对位基团，如甲氧基或卤素，反应通过取代基的置换进行。对于电负性较低的基团，如氨基或烷基，观察到保留取代基的吉布斯产物，这表明反应发生在邻位或间位。在酚类混合物中，吉布斯产物的相对强度与相对浓度成正比，最低可检测到1 μmol/L的浓度。该方法应用于商业烟熏液的定性分析，发现山核桃味和牧豆树味的酚类成分有显著差异。
