Development and Validation of an ICP-MS Method using Ammonium Fluoride to Replace Hydrofluoric Acid for Analysis of...

Several countries and regions have established regulations or guidelines specifying permissible limits for elemental impurities in cosmetic products. Surveys of commercially available cosmetics have shown that lipsticks often contain significant amounts of elemental impurities, which are of particular concern due to the high risk of oral exposure.

In this study, the elemental impurities in eight commonly used cosmetic ingredients were analyzed, namely silicon dioxide, titanium oxide, iron oxide, synthetic mica, natural mica, beeswax, Ricinus communis (castor) seed oil, and Lithol Rubine B.

Total dissolution of the samples was achieved via microwave digestion, employing an ammonium fluoride solution as a safer alternative to highly toxic hydrofluoric acid (HF). Subsequently, 14 elements-chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, strontium, cadmium, tin, antimony, mercury, and lead-were quantified by inductively coupled plasma mass spectrometry.

The limits of detection and quantification, as well as the accuracy and precision of the analytical method, were validated, confirming its suitability for the reliable determination of total elemental impurities in cosmetic ingredients. The inorganic ingredients contained relatively higher concentrations of elemental impurities than the organic ingredients. Se, Cd, and Hg were not detected in any samples.

The developed analytical method eliminates the requirement for HF, thereby enhancing analyst safety. Accurate determination and control of elemental impurity levels-particularly in inorganic cosmetic ingredients-are essential for minimizing contamination and ensuring product safety.

By avoiding the use of highly toxic HF, the analytical method presented in this study enhances analyst safety while maintaining high accuracy, rendering it a practical tool for cosmetic quality control and research and development.