A special case of medicine in disguise: Tattoo inks containing anaesthetics

This paper describes a case of medicine in disguise: seized tattoo inks containing lidocaine and tetracaine at high concentration. Identification of anaesthetics was performed by LC MS Q-TOF with ESI⁺ source, by accurate mass measurement and by comparing the fragmentation patterns of molecular ions, at 30 V and 10 V of collision-offset voltage, with reference standards. Quantification was also performed by LC MS Q-TOF on the chromatographic peaks in the extracted ion chromatograms, by calibration curves obtained at different standard concentrations and by standard additions approach. The measurement uncertainty was estimated from validation data. The paper gives also chromatographic parameters, MS and MS/MS data and a quantitation method, with a full validation, of other six "caines". Thus the paper intends to provide a tool for identification and quantitation of the most common local anaesthetics that could be fraudulently added to tattoo inks. The results here reported show that the seized samples of inks represent a serious health risk owing to the high anaesthetic content - therapeutic-like dosage - found.