Federal University of São Carlos, Sorocaba, SP, Brazil.
REQUIMTE/LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Porto, Portugal.
Talanta. 2018 Sep 1;187:113-119. doi: 10.1016/j.talanta.2018.04.091. Epub 2018 Apr 30.
Aldehydes are relevant analytes in a wide range of samples, in particular, food and beverages but also body fluids. Hydrazines can undergo nucleophilic addition with aldehydes or ketones giving origin to hydrazones (a group of stable imines) that can be suitably used in the identification of aldehydes. Herein, 4-hydrazinobenzoic acid (HBA) was, for the first time, used as the derivatizing agent in analytical methodologies using liquid chromatography aiming the determination of low-molecular aldehydes. The derivatization reaction was simultaneously performed along with the extraction process, using gas-diffusion microextraction (GDME), which resulted in a clean extract containing the HBA-aldehyde derivates. The corresponding formed imines were determined by both high-performance liquid chromatography (LC) with UV spectrophotometric detection (HPLC-UV) and capillary electrophoresis with diode array detection (CE-DAD). HBA showed to be a rather advantageous derivatization reagent due to its stability, relatively high solubility in water and other solvents, high selectivity and sensibility, reduced impurities, simple preparation steps and applicability to different separation and/or different detection techniques. Limits of detections (LODs) of the optimized methodologies (in terms of time and pH among other experimental variables) were all below 0.5 mg L, using both instrumental techniques. Furthermore, for the first time, the HBA-aldehyde derivatives were analyzed by LC with mass spectrometry (LC-MS), demonstrating the possibility of identification by MS of each compound. The developed methodologies were also successfully applied in the analysis of formaldehyde and acetaldehyde in several alcoholic beverages. This was also the first time GDME was combined with CE, showing that it can be a valuable sample preparation tool for electrophoresis, in particular by eliminating the interference of ions and inorganic constituents present in the samples.
醛类是广泛样本中相关的分析物，特别是食品和饮料，还有体液。肼类可以与醛类或酮类进行亲核加成，生成腙类（一类稳定的亚胺），可用于鉴定醛类。在此，4-肼基苯甲酸（HBA）首次被用作分析方法中的衍生化试剂，该方法采用液相色谱法，旨在测定低分子量醛类。衍生化反应与萃取过程同时进行，使用气体扩散微萃取（GDME），得到含有 HBA-醛衍生物的纯净提取物。通过高效液相色谱（LC）与紫外分光光度检测（HPLC-UV）和带有二极管阵列检测的毛细管电泳（CE-DAD），均可测定相应形成的亚胺。HBA 是一种相当有利的衍生化试剂，因为它稳定、在水和其他溶剂中的相对溶解度高、选择性和灵敏度高、杂质少、制备步骤简单，并且适用于不同的分离和/或不同的检测技术。使用两种仪器技术，优化方法（在时间和 pH 等实验变量方面）的检出限（LOD）均低于 0.5 mg/L。此外，HBA-醛衍生物首次通过 LC 与质谱（LC-MS）进行分析，证明了每种化合物都可以通过 MS 进行鉴定。所开发的方法还成功地应用于几种酒精饮料中甲醛和乙醛的分析。这也是 GDME 首次与 CE 结合，表明它可以成为电泳的有价值的样品制备工具，特别是通过消除样品中存在的离子和无机成分的干扰。
