Discrimination of Different Kinds of Iranian-made Kohl by Excitation-Emission Matrix Fluorescence Spectroscopy

Document Type : Research Paper


Chemistry Department, Shiraz University, Shiraz, Iran



Kohl is a traditional eye cosmetic used as eyeliner in different parts of Iran. They have different natural sources such as oils, nuts and leaves, and so on. They possess different physical and chemical properties and usually they have lead toxicity. The characterization of Kohl is evaluated as an important issue since it is directly affecting human health. So, in this study, kohl samples from various sources were characterized by different analytical methods such as scanning electron microscopy (SEM) and Energy-dispersive X-ray (EDX). Moreover, the sources of kohl samples were analyzed by three-dimensional (3-D) fluorescence spectroscopy. The fluorescence spectra of samples were evaluated by chemometrics methods to discriminate between different kohl sources. Principal component analyses (PCA) as unsupervised and extended canonical variates analysis (ECVA) as supervised classification methods were employed. PCA made relative discrimination between the various kohl samples and could only discriminate kohl stone from the others. Instead, more accurate classification results were achieved by ECVA and it represented sufficient ability for classification of all kohl samples. This study is the first study on Iranian-made kohl discrimination through 3-D fluorescence spectra and multivariate methods.