Determination of alternative preservatives in cosmetic products by chromophoric derivatization followed by vortex-assisted liquid–liquid semimicroextraction and liquid chromatography Pablo Miralles, Ilianna Vrouvaki, Alberto Chisvert, Amparo Salvador n Departamento de Química Analítica, Facultad de Química, Universitat de València, 46100 Burjassot, Valencia, Spain article info Article history: Received 12 February 2016 Received in revised form 10 March 2016 Accepted 11 March 2016 Available online 12 March 2016 Keywords: Cosmetic products Alternative preservatives Liquid chromatography abstract An analytical method for the simultaneous determination of phenethyl alcohol, methylpropanediol, phenylpropanol, caprylyl glycol, and ethylhexylglycerin, which are used as alternative preservatives in cosmetic products, has been developed. The method is based on liquid chromatography with UV spec- trophotometric detection after chromophoric derivatization with benzoyl chloride and vortex-assisted liquid–liquid semimicroextraction. Different chromatographic parameters, derivatization conditions, and sample preparation variables were studied. Under optimized conditions, the limits of detection values for the analytes ranged from 0.02 to 0.06 mg mL À1 . The method was validated with good recovery values (84–118%) and precision values (3.9–9.5%). It was successfully applied to 10 commercially available cosmetic samples. The good analytical features of the proposed method besides of its environmentally- friendly characteristics, make it useful to carry out the quality control of cosmetic products containing the target compounds as preservative agents. & 2016 Elsevier B.V. All rights reserved. 1. Introduction According to the European Regulation of Cosmetic Products (EC Regulation) [1], ‘cosmetic product’ means ‘any substance or mixture intended to be placed in contact with the external parts of the human body (epidermis, hair system, nails, lips and external genital organs) or with the teeth and the mucous membranes of the oral cavity with a view exclusively or mainly to cleaning them, perfuming them, chan- ging their appearance, protecting them, keeping them in good con- dition or correcting body odours’. Typical cosmetic formulation in- cludes active principles, excipients, and additives (colorants, per- fumes, preservatives, etc.). The Annex V of this regulation contains the list of the currently allowed preservative agents in cosmetics and the restrictions to be used, including their maximum con- centration, in order to ensure the safety of consumers. After the recent prohibition of some parabens by the European Commission [2], the cosmetic industries are continuously looking for new compounds that can perform the preservative function effectively and safely. In fact, it is well-known that some cosmetic ingredients can play more than one role in a cosmetic formulation. In this sense, according to the Inventory of Cosmetic In- gredients (2006/257/EC) [3], phenethyl alcohol (2-phenylethanol, PA) is used in cosmetics as deodorant; methylpropanediol (2- methyl-1,3-propanediol, MP) and phenylpropanol (3-phenyl-1- propanol, PP) are commonly employed as solvents; caprylyl glycol (1,2-octanediol, CG) acts as emollient, humectant and hair con- ditioning; ethylhexylglycerin (3-[(2-ethylhexyl)oxy]-1,2-propane- diol, EG) is used as skin conditioning. However, all of them show an important antimicrobial activity [4–13] and their use in the cosmetic industries is widespread due to their antimicrobial properties, being the subject of several patents [6,14–17]. Despite their preservative features, these compounds, whose chemical structures are shown in Fig. 1, are not listed as pre- servatives in the above mentioned Annex V of the European regulation. It is therefore necessary that the cosmetic companies have procedures to perform the analytical control of these alternative preservatives and to assure the quality of the final products con- taining them. However, there are not official methods to quantify the target compounds in cosmetic samples. Besides, to the best of our knowledge, there are not published analytical methods re- garding to their determination. Only a few articles in which PA was determined in alcoholic beverages, such as wine [18–20], beer [21,22] and alcoholic distillates [23] by chromatographic techni- ques have been published. Vortex-assisted extraction procedures have been successfully applied for sample preparation in the analysis of water [24–26], food and drinks [27–29], and also cosmetic products [30,31] with Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/talanta Talanta http://dx.doi.org/10.1016/j.talanta.2016.03.033 0039-9140/& 2016 Elsevier B.V. All rights reserved. n Corresponding author. E-mail address: amparo.salvador@uv.es (A. Salvador). Talanta 154 (2016) 1–6