# Recent Advances in Sample Preparation for Cosmetics and Personal Care Products Analysis
## 2 Sample Preparation Strategies for Cosmetics Analysis
### Microextraction Techniques for Cosmetic Analysis
#### 2.7.1 Liquid-Phase Microextraction Techniques
DES-VA-LLME was recently proposed to determine parabens in cosmetics oil products. The employed DES was prepared with choline chloride and ethylenglycol [94]. The whole DES-DLME-HPLC-UV method showed good recoveries and LODs at the low parts per billion [94]. A variation of VA-LLME, called vortex-assisted emulsification semi-microextraction (VAEsME) was successfully proposed for the determination of the preservative bronopol in cosmetics followed by HPLC-UV [95]. This approach allowed a fast one-step solution-extraction procedure which is very useful for the determination of ingredients with restricted concentrations, such as bronopol. Dispersive Liquid-Liquid Microextraction (DLLME)  
DLLME was introduced by [PERSON] et al. in 2006 [139]. In DLLME, a small volume of extracting solvent is dispersed by the action of a second solvent into the sample. The abundant contact surface of the fine droplets and the solvent phase greatly enhances the extraction efficiency, thus reducing the solvent volume needed and the extraction time [140]. DLLME has been applied for the cosmetics' extraction of a broad range of compounds including preservatives, fragrances, phthalates, and acrylamide [96; 97; 98; 99; 100; 101; 102]. The most critical experimental parameters affecting DLLME such as dispersive solvent, extraction solvent and volume, and extraction time, were optimized to obtain the highest extraction efficiency. High density solvents such as chloroform [96; 98; 99; 100], dichloromethane [97] or carbon tetrachloride [102] were the most employed ones, although the use of environmentally friendly alternatives, such as polymeric DES composed of DL-menthol and polyethylene glycol, has been proposed for the extraction of parabens from leave-on cosmetics [101]. Recently, anisole, a bio-derived solvent, was employed for the DLLME of UV filters from sunscreens, showing its suitability as a green alternative to classical organic solvents, not only to determine the target compounds' concentration in the formulations, but also in the skin after sunscreen application [103]. To improve the dispersion of the solvent into the cosmetic matrix, VA-DLLME has been mainly employed [100; 101], although the use of ultrasonic radiation (US), ultrasonic nebulization (UNE) or magnetic-stirring to assist in the DLLME of parabens, phthalates, UV filters and dyes have been also reported [102; 103; 104; 105]. For some analytes, especially for the more polar ones such as atrand and chloroatranol, in situ derivatization was performed to enhance their chromatographic response before GC analysis [99]. The use of DLLME-HPLC-DAD after performing other advanced extraction techniques such as PLE has also been proposed as an effective tool to determine vitamin E in cosmetics [106], showing good recoveries and LODs at the low ng g\({}^{-1}\). Other novel approaches in DLLME include methodologies based on ionic liquids (ILs), the solidification of the floating organic droplets (SFOD) or the use of low-density solvents (LDS) to substitute the use of organic solvents. IL-DLLME has been proposed as an environmentally friendly alternative prior to HPLC-DAD or CE analysis to extract dyes, preservatives, phenolic compounds or estrogens from cosmetics [107; 108; 109; 110; 111]. Methodologies based on DLLME-SFO were successfully employed for the extraction of phthalates from aqueous cosmetics [112] as well as for dyes from lipsticks [113]. In the last case, the extraction and clean-up steps were integrated to simplify the operation, achieving a high-throughput sample preparation. The main factors affecting the extraction efficiency were optimized by multi-response surface methodology and the validated method was applied to more than 120 cosmetics samples. The performance of DLLME-SFO was compared with LLE, UAE and classical DLLME, showing that DLLME-SFO was the most effective technique to extract phthalates from complex cosmetics matrices [109].