Abstract
Three Arabian eye kohl brands were analyzed for the presence of lead and cadmium using atomic absorption spectroscopy (AAS) and X-ray diffraction techniques. In this work, the chemical analysis of the samples was studied according to the concentration of heavy metals, solubility in different medium, reaction with KI, moisture, and organic contents. XRD pattern proposed the presence of some crystalline material in an amorphous background for all investigated brands. Mineral data analysis shows that the main minerals found in the samples are Manganoshadlunite in Natural Arab Kohl (NAK), samarskite in Natural Black Al-Athmod Kohl (NBAK), and kitaibelite in Black Al-Hashemi kohl (BHK). Physical properties such as color, forms, touch, and transparency are nearly the same for all samples but different in density, average pore diameter, and specific surface area. Atomic absorption spectroscopy (AAS) showed that the average percentage of Pb was in the range 0.2411 to 6.173 %; and from zero to 0.0019 % for Cd. The maximum concentration of Pb and Cd was found in Natural Arab Kohl (NAK) sample and is equal to 30.865 mg/g and 9.50 μg/g respectively. The minimum concentration of heavy metal was found in Natural Black Al- Athmod Kohl (NBAK) sample. Moisture was present in a very low percent (~ 1%) while organics was being in a reasonable amount (maximum ≥ 69%). All eye kohl brands are soluble in acidic medium with different proportions and forms the yellow precipitate of PbI2 when react with KI which is considered as a chemical evidence for the presence of lead. It is highly recommended to use Natural Black Al-Athmod Kohl (NBAK) only because it has low concentration of heavy metals (Pb and Cd), and has higher specific surface area. The risk factor for using these type of eye kohl is very low. The higher surface area helps in spreading the active ingredient leading to increase the treatability against eye disease.