An investigation on lead concentrations in different brands of lipsticks by using atomic absorption spectrometer assisted by microwave digestion

Lipsticks are one of the most popular cosmetic products among women. Recently it is stated that some of the lipsticks involve heavy metals, such as Lead, which have cancerous effects, and since I have lady friends, family members and teachers around me using lipsticks, I decided to investigate this issue. Even though it is in small amounts, it can accumulate in body and increase its negative effects rapidly if the lipstick usage is ongoing. So, I decided to investigate the amount of lead in randomly selected lipsticks, since I couldn’t access any literature value to compare because no company states the lead concentration in their products. My samples were Maybeline #475 Coral Diamonds, L'oreal #340 Sorbet Fraise Raspberry, Alix Avien #327, Golden Rose #216, and Pastel Lipstick #400. An atomic absorption spectrometer was used to determine amount of Lead in lipsticks. Lipstick sample consists of other compounds rather than lead, the solid sample needed to be digested, so an acid mixture of HNO3 and HF was used to prepare an aqueous solution. Though, the acid mixture itself is not sufficient enough to solve the lipstick sample. Microwave is used to assist the digestion process, which is the atomization stage, to obtain a homogenous solution. The research question is “How do the lead concentrations of different brands of lipstick samples solved in acid mixture and determined by using atomic absorption spectrometer vary under standard atmospheric conditions and room temperature and to what extent do they have hazardous effects?