Abstract
Vitamins are organic chemical compounds of low molecular weighs that are classified as either water-soluble (hydrophilic) or fat-soluble (lipophilic). Vitamins B, F, and H belong to the first category, while fat-soluble vitamins A, D, E, and K belong to the second. While some vitamins can be synthesized, others must be received from a balanced diet. Vitamins regulate metabolic processes, support the immune system, and perform a variety of other crucial activities in the pharmaceutical and cosmetic industries. Due to their sensitivity to light, heat, moisture, and oxygen, they have been identified as labile compounds. As a result of these limitations, it has been suggested that derivatives of these vitamins, must be used instead, as they have been shown to be more stable than their parent molecules. Vitamin derivatives, such as tocopheryl acetate and retinyl palmitate, are compounds of vitamins with other substances, and are usually esters of acids such as acetic acid and palmitic acid (INCI (International Nomenclature of Cosmetic Ingredients) terms). These vitamins provide a variety of skin benefits, the most important of which is their antioxidant properties. These compounds have this effect because they can prevent or reduce cell damage produced by free radicals. Other advantages provided by these active components include collagen stimulation, wrinkle reduction, melanin decomposition, faster wound healing, and protection from the suns’ UV rays, among others. Nevertheless, these active ingredients in cosmetics products must be regulated, and this emphasizes the significance of quality control, particularly through analyzing their contents, in ensuring efficacy and safety of their use. To obtain high extraction efficiency, a sample preparation technique that is well suited for these compounds must be used. Previous research studies have made use of several sample preparation techniques to extract these compounds, however the drawback is that these techniques do not meet today's green principles. As a result, arising from these challenges, the purpose of this study is to develop green sample preparation techniques to help overcome the limitations of traditional extraction methods such as solvent extraction (SE) and soxhlet extraction (SE) for the extraction and determination of vitamins. To accomplish this, the study's aim is to remove vitamins from cosmetic samples using two separate sample preparation techniques, which are ultrasound-assisted solvent extraction (UASE) and supramolecular solvent-based vortex-assisted liquid-liquid microextraction (SUPRAS-VA-LLME).
The first aim of this was to develop an ultrasound-assisted solvent extraction (UASE) technique for extracting vitamins A and E from cosmetics before determining their concentrations using high-performance liquid chromatography with diode array detection
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(HPLV-DAD). It was found that the combination of Aliquat 336 and 1-octanol, a supramolecular solvent (SUPRA), extracted the vitamins better than the two deep eutectic solvent combinations (DESs) that were also investigated. The limits of detection (LOD) and limit of quantification (LOQ) ranged from 6.3 μg/L and 2.5 μg/L to 21.1 μg/L and 8.4 μg/L, under optimal conditions. The linearity ranges were between 0.021 - 1140 μg/L and 0.008 – 1140 μg/L. The precisions (expressed in terms of % RSD, n = 7) were 4.1 % and 3.0 %. For the extraction and determination of vitamins A and E, the recovery ranged from 95 - 107 %, demonstrating the presence of these vitamins in spiked cosmetic samples. The results clearly confirmed the existence of vitamin A and E, demonstrating that the proposed method was suitable for routine analysis of these vitamins.
In order to achieve the aim for the study, a quick and ecologically friendly sample preparation process was applied to extract vitamin C from cosmetic samples. The method used ultraviolet-visible (UV-Vis) spectroscopy to quantify after extraction using a supramolecular solvent-based vortex-assisted liquid-liquid microextraction (SUPRAS-VA-LLME) procedure. Fractional factorial design and central composite design with desirability functions were used to screen and optimize the parameters affecting the experimental technique. When compared to two other supramolecular solvents (SUPRAS) combinations studied, the combination of a mole ratio of 2:1 decanoic acid to tetrahydrofuran resulted in a higher percentage of vitamin C recovery. The methods coefficient correlation was established to be 0.9938, while the developed method's lower limit of quantification (LLOQ) was discovered to be 0.07 mg/L. The vitamin recoveries were greater than 80 % in two different products, whereas the RSD (relative standard deviation) was found to be less than 6 %. The method worked well in spiked samples that had vitamin C in their formulations, as indicated on the ingredient list of the product.