Application example - Determination of 15 rare earth elements such as neodymium in cosmetics (ICP-MS method)

Introduction

Rare earth elements such as neodymium exist widely in nature and may be mixed in trace amounts during the production of cosmetics. According to the latest "Cosmetics Safety Technical Specifications"

(2015 edition) stipulates that 15 rare earth elements such as neodymium are restricted components. normal

The use of cosmetics containing trace amounts of rare earths is less harmful to consumers' health, but rare earth elements exceeding a certain content will have certain biological toxicity, and long-term exposure will cause harm to the human body. For example, rare earth elements are obvious hepatotoxic agents, which can interfere with the metabolism of sugar, fat, protein, nucleic acid and drugs. After rare earth element poisoning, skin symptoms such as folliculitis, skin itching, dryness, and hyperpigmentation often occur. Among them, neodymium is highly irritating to the eyes and mucous membranes, moderately irritating to the skin, and long-term absorption can also lead to pulmonary embolism and liver damage.

Experimental part

sample preparation

Weigh 0.1 - 0.3 g of sample, accurate to 0.0001 g, and place it in a polytetrafluoroethylene-tetrafluoroethylene (PTFE-TFE) high-pressure digestion vessel washed with acid, add 5 mL of nitric acid

(Add a small amount of hydrofluoric acid if necessary), 2 mL of hydrogen peroxide solution. Cover and place the digestion vessel on a hot plate for pre-digestion (80 °C) for 30 - 40 min, then allow it to fully

cool down. Heat and digest according to the pre-set digestion program of the microwave digester. After the digestion procedure, cool down to room temperature, open the digestion tank, transfer the sample digestion solution to a clean 50 mL polyethylene terephthalate (PET) plastic bottle, and wash the digestion tank and lid with a small amount of water for 3-4 time, the lotion was incorporated into a PET bottle, fixed to 50.00 g, and mixed. A blank test was performed with the sample.

Experimental results

Drawing of standard curve: prepare standard solutions of 0.00, 0.50, 1.00, 5.00, 10.0, 20.0, 50.0, 100 µg/L series for all elements, and draw standard curve.

Detection limits of 15 rare earth elements including neodymium in cosmetics by ICP-MS (unit: µg/L)