Investigation of the Elemental Profile of Petroleum Jelly-Based Personal Care Products by ICP-MS

Hair-relaxing kits are used by many women, a high percentage of whom are African American, to transform curly hair to straight hair. Almost all varieties consist of extremely caustic solutions that demonstrate pH values in the range of 10–14. Because of the harshness of this alkaline reagent, petroleum jelly (petrolatum) is often times incorporated into the composition to protect the scalp. Petrolatum, a highly organic byproduct of crude oil, is widely used in cosmetics and topical pharmaceuticals as well. This article reports the elemental composition of various brands of hair-relaxing creams. Several sample preparation techniques were investigated for the digestion of this very organic, viscous matrix. Inductively coupled plasma-mass spectrometry was used for its multi-element capability and high sensitivity. Internal standard calibration was used in the quantitation of a select group of metals, transition metals, and metalloids (Ti, V, Cr, Co, Ni, Ga, Ge, As, Se, Rb, Sr, Zr, Nb, Mo, Ag, Cd, Cs, Ba, W, Re, Tl, Pb, U) and the established method was applied to various brands of hair-relaxing kits. Major elemental constituents were Ti, Sr, and Ba, and these were found at low µg g⁻¹ in all brands considered.