Sample Preparation and Analysis of Cosmetics Using Sequential Microwave Digestion

Introduction

Cosmetics and beauty products have been used by humans throughout our history; eyeshadow and blush have been present since BCE in both Egyptian and Greek cultures. Human use of cosmetics has only increased since, with an estimated current global market size of 299.77 billion. From the everyday application of sunscreen or lotion to the use of makeup for beauty enhancement or special effects, cosmetics and topicals are regularly used in daily life. Metals have a long history of use as colorants in cosmetics, with iron oxides being common in concealers and aluminum in lipsticks. Other uses for the metals include as preservatives, antiperspirants, and UV filters. Many heavy metals such as arsenic, cadmium, lead, and mercury can be toxic to humans and, as such, must be analyzed and regulated in consumer products. Regular use, coupled with the method of application, makes accurate heavy metals analysis of special concern in cosmetics.

In this study, cosmetics were digested using the BLADE microwave digestion system and analyzed on an Agilent ICP-OES. Traditional heavy metals of concern such as Pb, Hg, As, and Cd, as well as other metals tested by the FDA, and ones commonly used in cosmetics were analyzed. Titanium and silicon were specifically examined due to their historic uses in makeup.