<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>32</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Tasnim Mouazen</style></author><author><style face="normal" font="default" size="100%">Tamara Vanhaecke</style></author><author><style face="normal" font="default" size="100%">Bart Desmedt</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Determination of lawasone and paraphenylenediamine in henna tattoos and hair dyes through UPLC-PDA</style></title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Henna</style></keyword><keyword><style  face="normal" font="default" size="100%">lawsone</style></keyword><keyword><style  face="normal" font="default" size="100%">PPD</style></keyword><keyword><style  face="normal" font="default" size="100%">standard addition</style></keyword><keyword><style  face="normal" font="default" size="100%">standard calibration</style></keyword><keyword><style  face="normal" font="default" size="100%">UPLC-PDA</style></keyword><keyword><style  face="normal" font="default" size="100%">Youden calibration</style></keyword></keywords><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;&lt;strong&gt;Introduction:&lt;/strong&gt; For centuries, henna with its active substance lawsone has been used in&lt;br&gt;
the Arab and Hindu cultures as a hair dye or as expression of body art by applying it on&lt;br&gt;
the hands, feet, and body. This form of pure or red henna with lawsone as active ingredient&lt;br&gt;
is potentially genotoxic whereas the temporary black henna tattoo has been reported to&lt;br&gt;
cause allergic skin reactions due to the presence of the skin sensitizer&lt;br&gt;
paraphenylenediamine (PPD).&lt;/p&gt;

&lt;p&gt;&lt;br&gt;
&lt;strong&gt;Aim:&lt;/strong&gt; To develop and validate a fast UPLC-PDA method to simultaneously determine&lt;br&gt;
lawsone and PPD in henna tattoos and hair dyes with the purpose to evaluate their potential&lt;br&gt;
risk for the consumers.&lt;/p&gt;

&lt;p&gt;&lt;br&gt;
&lt;strong&gt;Material and methods: &lt;/strong&gt;Extraction of the target molecules is performed by adding the&lt;br&gt;
extraction solvent MeOH to the henna sample. Hereafter, the sample undergoes ultrasonification,&lt;br&gt;
centrifugation and filtration before analysis with the UPLC-PDA device. A&lt;br&gt;
simple C18-column is used and reverse phase chromatography with a final flow of 0,3&lt;br&gt;
mL/min is performed. The conducted methods are standard calibration, standard addition,&lt;br&gt;
Youden calibration and combining two SAC with different sample weights.&lt;br&gt;
Results: Applying a standard calibration method resulted in low recovery for lawsone (74,2&lt;br&gt;
%). Various attempts such as an additional ultra-sonification step, extraction in three steps&lt;br&gt;
or extraction solvent change over resulted in optimal conditions for the method to undergo&lt;br&gt;
method validation. Unfortunately, due to the occurrence of peak splitting and shoulder&lt;br&gt;
formation and the reoccurrence of low recoveries for lawsone and PPD, no method&lt;br&gt;
validation could be conducted. Due to the occurrence of matrix adsorption effect, a&lt;br&gt;
standard addition method was performed whereby the matrix effect was, however, not&lt;br&gt;
eliminated. Therefore, another method to determine the sample composition was&lt;br&gt;
approached, namely combining SAC and YC or combining two SAC with different sample&lt;br&gt;
weights. When comparing the calibration lines of SAC and SAC’, two non parallel lines were&lt;br&gt;
obtained, indicating that the matrix effect was not constant and can be considered as an&lt;br&gt;
incorrigible error.&lt;/p&gt;

&lt;p&gt;&lt;br&gt;
&lt;strong&gt;Conclusion:&lt;/strong&gt; Due to the matrix interference that is considered as an incorrigible error, the&lt;br&gt;
method is not developed or validated. In the future, the analyst should try to identify the&lt;br&gt;
interferent and develop a method that results in separate signals for the interferent and&lt;br&gt;
the analyte.&lt;/p&gt;
</style></abstract></record></records></xml>