Determination of lead content in whitening cream using laser induced breakdown spectroscopy analysis

Abstract

Laser Induced Breakdown Spectroscopy (LIBS) technique was applied to determine the concentration of heavy metal such as Pb in five different whitening creams available from retail shop and open market in Johor, Malaysia. The whitening cream in the form of an emulsion was painted on the glass slide and then cryogenically frozen in refrigerator. The harden sample of whitening creams were irradiated with light Q-switch Nd:YAG laser at five different positions on the same sample. The spectral lines of six whitening creams were identified using National Institute of Standards and Technology (NIST) Database. Finally, Pb was detected in all the studied samples and their concentration in the range of 1.78 ppm – 4.64 ppm with limit of detection which is ~ 1 ppm. The LIBS results were validated by Inductive Couple Plasma Mass Spectroscopy (ICP-MS) technique with percentage difference in the range of 2.73% – 7.60%. The detection of Pb in the whitening creams is under permissible limit as set by Malaysian standard. However, the limitation is over as set by WHO which is 0.05 ppm for daily used. Thus, it is better to take precaution because continuously using creams may lead to accumulative toxicity in the body beyond the acceptable limit. Thus, the high sensitivity, portable and in-situ system allow LIBS to be an important technique in cosmetic industries.