Wolf Carina, Krall Franziska, Göldner Valentin, Karst Uwe
Institute of Inorganic and Analytical Chemistry, University of Münster, Münster, Germany.
Department of Environmental Geosciences, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.
Anal Bioanal Chem. 2025 Jan 4. doi: 10.1007/s00216-024-05709-8.
Tattooing is a popular form of body art that has evolved from ancient times into being part of modern society. The understanding of biotransformation processes of coloring tattoo pigments in human skin is limited although skin reactions to tattoos with unknown culprits occur. Electrochemistry coupled to mass spectrometry (EC-MS) has widely been used as a tool for a purely instrumental approach to simulating the enzymatic biotransformation of xenobiotics. For the application to pigments, however, clean standards are lacking. Hence, metabolic studies in general as well as simulation approaches like direct EC-MS are hindered because transformation products cannot be assigned unequivocally to the pigment or its impurities. This can be addressed by online separation prior to electrochemical transformation. An online-liquid chromatography (LC)-EC-MS approach was developed to simulate the metabolism of Pigment Red 5 (PR 5). The electrochemical cell was coupled to the chromatographic column and was operated in oxidative and reductive mode. Distinct retention times allowed the electrochemical transformation products to be linked to their parent compound. Oxidative and reductive azo cleavage of PR 5 were observed. Two different PR 5 formulations were investigated, yielding the same transformation products and showcasing the applicability to individual PR 5 samples with different impurity profiles. The presented LC-EC-MS approach overcomes the lack of clean standards that hampers the metabolic studies of tattoo pigments in general and using direct EC-MS without prior chromatographic separation. Applying the purely instrumental online separation approach, first ideas on possible transformation routes of pigments frequently identified in adverse skin reactions are provided.
纹身是一种流行的人体艺术形式，它从古时候演变而来，如今已成为现代社会的一部分。尽管人们会出现不明原因的皮肤对纹身的反应，但对于纹身色素在人体皮肤中的生物转化过程的了解仍然有限。电化学联用质谱法（EC-MS）已被广泛用作一种纯粹的仪器方法，用于模拟外源性物质的酶促生物转化。然而，对于色素的应用而言，缺乏纯净的标准品。因此，由于无法明确将转化产物归属于色素或其杂质，一般的代谢研究以及像直接EC-MS这样的模拟方法都受到了阻碍。这可以通过在电化学转化之前进行在线分离来解决。开发了一种在线液相色谱（LC）-EC-MS方法来模拟颜料红5（PR 5）的代谢。将电化学池与色谱柱联用，并以氧化和还原模式运行。不同的保留时间使得电化学转化产物能够与其母体化合物相关联。观察到了PR 5的氧化和还原偶氮裂解。研究了两种不同的PR 5制剂，得到了相同的转化产物，并展示了该方法对具有不同杂质谱的单个PR 5样品的适用性。所提出的LC-EC-MS方法克服了缺乏纯净标准品的问题，而这一问题通常会阻碍纹身色素的代谢研究，以及在没有事先色谱分离的情况下使用直接EC-MS的研究。应用这种纯粹的仪器在线分离方法，提供了关于在不良皮肤反应中经常发现的色素可能的转化途径的初步想法。
