Simultaneous Elemental and Molecular Mass Spectrometry of Tattoo Inks and Tattooed Skin Biopsies: A Novel Laser Ablation-Based Technique for Tattoo Pigment Analysis

The increasing prevalence of tattoos and the frequent occurrence of adverse skin reactions, particularly from colored inks, highlight the urgent need for reliable analytical methods to identify potentially harmful substances in tattoo inks and tattooed skin. In this study, a novel, laser-based technique enabling combined molecular and elemental analysis is presented: Laser Ablation hyphenated to Atmospheric Pressure Chemical Ionization-Mass Spectrometry (LA-APCI-MS) and Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS/APCI-MS). This instrumental setup allows the simultaneous detection of organic and inorganic pigments as well as their metallic contaminants directly in solid samples. A newly developed spectral pigment libraries based on MS¹ and MS² data enables precise identification of organic pigments within complex matrices such as inks or skin sections. Using five commercially available tattoo inks, this new technique reliably identified nondeclared or even prohibited organic pigments and different metals. In skin biopsies from red tattoos with adverse reactions, different organic pigments and metals were localized via bioimaging, revealing distribution patterns that may help to uncover the causes of allergic responses. The introduced LA-ICP-MS/APCI-MS technique offers a rapid and powerful approach to obtain complementary information on organic pigments, inorganic compounds, and metals from a single sample. As such, it represents a significant advancement for investigating tattoo-related side effects, supporting risk assessment, and ensuring regulatory compliance.