Systems for Microwave-Assisted Wet Digestion

Matusiewicz, Henryk

doi:10.1016/b978-0-444-59420-4.00003-9

Cited by 9 publications

(1 citation statement)

References 74 publications

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“…The cosmetic sample is placed in the digester with the acid or the mixture of acids and possibly H 2 O 2 . Then, in order to achieve the quantitative decomposition and destruction of the organic materials, the digesters are placed in autoclaves (shells) made of Teflon (TFH), where they are then heated with the help of microwaves [15,16]. The increase in the temperature results in an increase in the pressure inside the autoclave system and therefore an increase in the reactivity of the acids.…”

Section: Methodologies For the Preparation Of Cosmetic Products 21 We...mentioning

confidence: 99%

Sample Preparation of Cosmetic Products for the Determination of Heavy Metals

2022

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The sample preparation of a cosmetic specimen in Cosmetic Science for the purpose of determining the analytical composition of heavy and toxic metals such as lead (Pb), mercury (Hg), cadmium (Cd), and arsenic (As) is of particular importance due to the difficulty of handling the sample. There are two main methods of sample preparation. The first method is the wet digestion of the sample with strong acids such as H2SO4, HNO3, HF, and HNO3/HCl (1:3) and the combination of a strong acid with H2O2. Liquid digestion of the sample under the influence of strong acids damages the organic material of the sample and converts the carbon into carbon dioxide. The contained metals are oxidized to the highest oxidizing step and converted to soluble salts. A problem with this method is the loss of metals during digestion because it occurs at high temperatures as well as the decrease in the concentration of the residual acid. The second method of preparation is the wet liquid digestion of the sample with strong acids in a microwave oven in a closed vessel. The acids that are used are mainly HNO3 or mixtures of acids such as HNO3–HCl and HNO3–H2SO4. When the sample in the acid’s solvent is exposed to microwave energy, it can reach temperatures substantially above the boiling temperature of the acid solution. The result is the decomposition of the organic material, the oxidation of the metals, and their conversion to soluble nitrates. The advantages of using microwaves are the ability to control the temperature, pressure, and loss of metals and, thus, avoid erroneous measurement results. Simultaneously with the above, extraction methods have been, for almost a decade, very effective complementary processes that we can use to enrich a sample of a cosmetic product. Liquid–liquid dispersion micro-extraction (DLLME) and solid phase extraction (SPE) are the two main methods used in sample preparation and are usually applied after the digestion process.

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Section: Methodologies For the Preparation Of Cosmetic Products 21 We...mentioning

confidence: 99%