Determination of Para-Phenylenediamine (PPD) in Henna Samples Collected from Libyan Local Markets Using Spectrophotometric Method

Abstract

Henna is one of the most popular cosmetics in Libya. It is used as a paste applied to the body or the hair. Para-phenylenediamine (PPD) is added to henna to make it darker. However, PPD can increase the risk of allergic contact dermatitis according to the Scientific Committee on Consumer Products (SCCP). In this research, the concentration of PPD of eight types of natural and commercial henna was determined. The UV-vis spectrophotometric method with the ninhydrin reagent in an alkaline methanol solution was used to measure the PPD of analyzed samples at 430 nm. The results of tested samples were linear in the concentration range of 0.2–1.2 µg/ml. Most of the results were in the range of 2.6-4%, which is within the permissible limits according to the SCCP, however, there was the exception of the henna sample (H5) (11% w/w), which showed the highest percentage of PPD. Caution must be taken with this type of henna because it may cause skin allergies. These results indicate the necessity of regulatory and supervisory requirements for producing and distributing contaminated henna products.