Rapid Colorimetric Analysis of para-Phenylenediamine in Henna-based, Non-permanent Tattoo Color Mixtures Christopher T. Kruger; Dirk W. Lachenmeier, PhD; Evamaria Kratz; and Gerd Mildau , PhD Chemisches und Veterintiruntersuchungsamt (CVUA) Karlsruhe, Karlsruhe, Germany KEY WORDS: para-phenylenediamine, Law50nia plant, skin, contact dermatitis, cosmetics ABSTRACT: In some henna mixtures, para-phenylenediamine (PPO) has illegally been added and it is responsible for complications such as allergic contact dermatitis. While high-performance liquid chromatography has previously been used to detect PPD, a colon'met6c method that is joster and portable, desc6bed here, has been developed. For product developers, this method can be used to evaluate henna plant extracts. T attoos have been used throughout history as body decorations and they comprise an integral element of various cultures.' However, many individuals are uncomfortable with the fact that tallooing is virt ua lly irreve rs- ible since dyes are injected under the skin into the dermis. An alternative that has grown in popularity is tem - porary talloos based on henna. This treatment is normally safe and does not injure the skin surface; it involves exposing the skin externally to a henna tattoo mixture that contains ground henna leaves mixed with water or oil. The natural dye in henna leaves is 2-hydroxy-I,4-naphtoquinone (Law- sone),l which reacts on the skin surface with skin proteins, leading to a tempo- rary orange-brown coloring of the skin. Natural henna tattoo mixture- Le., without para-phenylenediamine (PPO), is applied using semi-conical containers to make it easier to achieve el aborate designs and is left on the skin for three to six hours. The longer the exposure time, the darker the final color, which is never black as is often assumed, but a dark orange-brown.' By adding PPO to the henna tattoo mixture, the application time can be Significantly reduced and the results appear more like the desired black colo r. ' However, the autoxidation products ofPPO including Bandrowski's base, a trimer of PPO, are very strong potential skin sensitizers,' thus the addition of PPO is responSible fo r most reported skin complications arising from th e use of black henna, The natural dye in henna leaves is 2·hydroxy·l, 4·naphtoquinone (Lawsone), which reacts on the skin surface with skin proteins. such as allergic contact post-inflammatory hyperpigmentation/ or even worse, an allergic sensitization to PP08-'O and the many substances that cross-react with it, including para- aminophenol, para -toluenediamine or many azoic dyes, such as disperse orange 3." PreViously, studies using high - performance liquid chromatography (HPLC)-based methods for the iden- tification and quantification of PPO in black henna have been published. For in sta n ce, using HPLC with a refractive index detector, Al-Suwaidi and Hamcd 'z investigated 25 henna samples with II black henna samples among them, which were purchased from 15 different hen na salons in the United Arab Emir- ates. PPO was found in all black hen na samples in concentrations ranging from 0 .4% 10 29.5% w/w. Brancaccio et al Y also detected PPO at 15.7% wlw by investigating the black henna tattoo mix to which their patient developed contact allergy using HPLC with a diode array detector and an electrospray mass- spectrometric detector. Such reported high concentrations of PPO in black henna tattoo mixtures give cause for concern, as even a 10% concentration was shown to sensitize all 24 subjects in a human maximi Zation study. '· And due to PPO's allergenicity, the Euro pean Union has legislated against allowing its direct application to skin or for dyeing eyebrows and eyelashes. Further, the US Food and Drug Administration has prohibited the application of PPO direc t ly on the skin. tl Due to the current consumer rel - evance of henna tattOOing, an assay for detecting PPO in henna mixtures rap- idly and during on -s ite controls would be an advantage, as suspected samples could be immediately confiscated by control authorities. However, literature on such assays has not previously been 496 I Cosmetics & Toiletries· magazine Re{JfOduction in English or ""Y o!her l onguage at all or port at thil ottide is s!Jict1y prohibited. c> 2011 Allured Publishing CO/P. Business Media. Vol. 126. No. 7jJuly2011