# Recent Advances in Sample Preparation for Cosmetics and Personal Care Products Analysis
## 2 Sample Preparation Strategies for Cosmetics Analysis
### Microextraction Techniques for Cosmetic Analysis
#### 2.7.2 Sorbent-Based Microextraction Techniques
In this last case, the desorption was performed, employing a small volume of organic solvent. The combination of different extraction techniques with SPME is attracting significant attention. For example, \(\mu\)-MSPD in combination with SPME was employed as a fast and reliable tool to extract multiclass preservatives (benzoates, parabens, triclosan, butylhydroxy-toluene and butylhydroxyanisole) from cosmetics as well as to monitor their photo-transformation after solar radiation [126]. This is important since cosmetics, especially leave-on ones, are in prolonged contact with the skin, and exposure to solar radiation may not only cause the inactivation of the preservatives, but may also produce potentially hazardous photoproducts. The combination of supercritical fluid extraction (SFE)-online-SPME has been employed to extract multiclass preservatives including parabens and antioxidants from cosmetics [127]. The analytes were extracted from the matrix with supercritical CO\({}_{2}\). Since analysis was performed by GC-MS, an in situ derivatization step was necessary to improve the chromatographic peak shape of the parabens. Finally, analytes were adsorbed on a polyacrylate (PA) fibre. The combination of a purge-trap with a headspace needle trap device (NTD) and portable GC-MS analysis has also recently been proposed to determine the antioxidant BHT in cosmetics [128], demonstrating the feasibility of utilizing a hand-portable GC-MS for the real-time estimation of this compound, facilitating quality control measurements by inspecting agencies. SPME has also been proposed as a very promising, non-invasive, and fast technique to evaluate the presence of bacteria (_Escherichia coli_, _Pseudomonas aeruginosa_, or _Proteus mirabilis_ among others) in cosmetics. Most of the currently employed techniques for this purpose, including the official methodology, are based on the colony-forming units (CFUs) count and although they employ low-cost materials, they are laborious and require several steps, also being highly time consuming (up to 72 h). It is well known that bacteria produce microbial volatile organic compounds (MVOCs), which are formed during bacterial metabolic processes. This way, SPME employing commercial PDMS/DVB/CAR fibres has been employed to perform an in situ extraction and preconcentration of the MVOCs in a single step [133; 134]. Afterwards, GC-MS has been employed as determination technique to unequivocally identify the MVOCs derived from the enzymatic activity, allowing the identification of several of them as specific markers for each one of the studied bacteria, as well as others as general indicators of bacteria presence. Fabric phase sorptive extraction (FPSE) has recently been developed by [PERSON]'s and [PERSON]'s group [146]. FPSE uses small squares of cellulosic (or other) fabric coated with a thin sol-gel, which are directly immersed in the samples to sorb and extract analytes. Analytes' desorption is performed by immersing the FPSE device into a small volume of solvent and can be assisted by US or vortex agitation to accelerate the analytes' transfer to the solvent. The use of a fabric-phase sorptive extraction membrane provides a high surface area which offers high sorbent loading, shortened equilibrium time, and an overall decrease in the sample preparation time. It has mainly been applied to extract different organic contaminants from environmental matrices [147]. Although it is a very recent extraction technique, it has been applied, followed by HPLC-DAD, to the determination of parabens in cosmetics [135; 136]. The main experimental parameters affecting extraction such as FPSE membrane coating, sample pH, or desorption solvent were optimized, showing that both carboxen (CW-20) and PEG membrane coatings were suitable to extract parabens. Satisfactory recoveries and precision were achieved and LODs at the ng mL\({}^{-1}\) were obtained. The FPSE membrane can be reused several times without losing extraction efficiency, showing the suitable applicability of this recent technique to cosmetics.