GC–MS Analysis of Laser‑Degraded Blue Tattoo Ink

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Laser irradiation of blue tattoo ink can create toxic byproducts - including hydrogen cyanide (HCN) - according to new research published by scientists at the German Federal Institute for Risk Assessment.¹ Pyrolysis gas chromatography–mass spectrometry (Py–GC–MS) was performed on samples of copper phthalocyanine blue to predict the decomposition products resulting from irradiation, as part of a wider on-going project assessing the safety of tattoo inks.

Tattooing permanent body art onto the skin with ink is practiced worldwide, whether to express individual identity or for cultural beliefs. Unfortunately for some, this permanence can become a problem and laser removal treatments have become a popular way of removing unwanted tattoos. Corresponding author Andreas Luch from The Free University of Berlin told The Column: “To work and compile a ‘white list’ of safe pigments for this field of application all possible risk scenarios must be considered - from the initial process of tattooing, lifelong distribution of pigment particles throughout the body, sunlight exposure, and the removal of no longer wanted tattoos. The latter is usually carried out by laser irradiation. The current study is thus dealing with risks associated to laser treatment of the light-fast and blue pigment copper phthalocyanine, which is commonly used in blue tattoos. This has never been investigated before.”

Py–GC–MS was applied to samples of copper phthalocyanine blue leading to the detection of four main products - HCN; 1,2-benzene dicarbonitrile; benzonitrile; and 2-butanone. The investigators then performed dynamic headspace sampling of laser treated pigment solutions followed by GC–MS to quantify HCN and benzene; or GC×GC–TOF-MS to quantify other fragments. Luch said: “GC×GC–TOF-MS is characterized by its high chromatographic resolution and sensitivity enabling the detection of even small amounts of newly formed decomposition products after laser irradiation. We wanted to screen our samples for trace products and its structural isomers. The establishment of a quantitative method for the two main decomposition products of copper phthalocyanine (benzonitrile and 1,2-benzene dicarbonitrile) was based on these screenings.”

The profile of breakdown products generated by Py–GC–MS treatment of the ink was comparable to that resulting from laser treatment, meaning that Py–GC–MS could be used to predict the breakdown products of tattoo inks in future toxicological studies. According to the paper, the detection of HCN and benzene byproducts following irradiation of tattoo ink is a concern because both are highly toxic. As a follow-up to these findings, the authors plan to model laser tattoo removal in real skin specimens to calculate the exposure of individuals to the toxic products produced. Luch said: “Since animal experiments are prohibited in the cosmetics sector including tattoo inks, we will try to get more information by studying pig skin ex vivo, which will be tattooed afterwards with common pigments used in tattooing and then be investigated.” - B.D.

Reference
1. I. Schreiver, C. Hutzler, P. Laux, H.P. Berlien, and A. Luch, Scientific Reports DOI: 10.1038/srep12915 (2015).

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