J. Cosmet. Sci., 68, 1–10 ( January/February 2017) 1 Determination of benzalkonium chloride in wet wipes by using a validated capillary electrophoresis method GÜNEȘ YILDIRIM and EBRU TÜRKÖZ ACAR, Department of Analytical Chemistry, Faculty of Pharmacy, Yeditepe University, Istanbul, Turkey. Accepted for publication September 12, 2016. Synopsis Benzalkonium chloride (BAC), which is a mixture of C8 and C18 alkylbenzyldimethylammonium chlorides, has an important biocide character and is used in many cosmetics, especially wet wipes, as a preservative and/ or antibacterial agent. The concentration range of BAC is 0.005–0.5 % and it is an irritant substance when used at high concentrations. Thus, the concentration of BAC should be carefully monitored in commercial products intended for skin use. In this study, a capillary electrophoresis (CE) analysis method for BAC quantifi cation was developed. The quantitative analysis was carried out by the external standard method. The electrophoretic separation was performed by using 75 mM (pH 6.0) phosphate buffer solution containing 30% acetonitrile as the electrolyte. The separation voltage was 10 kV and the temperature was held at 18°C. Samples were introduced into the capillary column hydrodynamically using 50.0-mbar pressure over a 3-s period. The developed method was validated and applied on samples prepared by wringing out antibacterial wet wipes containing BAC without any further extraction. The linearity of the method was controlled by applying the Mandel test. The limit of detection (LOD) values for the developed method were 0.313 and 0.309 μg/ml and the limit of quantifi cation (LOQ) values were 1.042 and 1.029 μg/ml for C10 and C12 derivatives, respectively. INTRODUCTION The use of wipes is becoming very popular for the purpose of general house cleaning or make-up remover, as well as for personal hygiene both in adults and babies. Besides this growth, wet wipes are used more than once daily due to practical usage. Different materials are used to provide cleaning effi ciency in the wetting solution of wipe tissues. These materials contact with skin especially when the products are used for cosmetic or personal hygiene/cleaning, and can lead to different skin disorders. According to the literature, there are some cases reported declaring usage of wet wipes caused allergic contact dermatitis (ACD) (1–4). Reason of ACD in these cases was from some preservatives used in wetting solution of wipe tissues. One of these preservatives is benzalkonium chloride (BAC). BAC is a quaternary ammonium cationic surfactant that is widely used as a biocide and/or a preservative in cosmetics, skin disinfectants, or ophthalmic preparations (5–6) (Figure 1). Address all correspondence to Ebru Türköz Acar at ebruturkozacar@gmail.com.

JOURNAL OF COSMETIC SCIENCE 2 Nevertheless, BAC has also been demonstrated to be a signifi cant skin irritant causing ACD. Indeed, Oiso et al. (7) reported an ACD case due to a shampoo containing BAC at a concentration of 0.1% (w/v). Also, results of studies carried out by Kanerva et al. (8) using patch testing showed an irritant response of BAC when used at concentrations of 0.1% (w/v). Since BAC concentrations in wet wipes vary from 0.05% to 0.5 % (w/v) (9), these products are susceptible to cause contact dermatitis and/or ACD on skin, especially on babies skin as wipes can be used several times a day for cleansing their bottoms. Therefore, the BAC concentration should be carefully monitored in wet wipes and should not exceed a concentration of IC50 (ACD)/10 in baby products to provide a suitable safety factor. BAC can be monitored via titrimetric methods (10–12), ultraviolet–visible (UV-Vis) spectroscopy (13,14), liquid/gas chromatography (15–21), or capillary electrophoresis (CE) methods (22–26) as reported in studies that investigate BAC concentrations in some pharmaceuticals and cosmetics. However, to the best of our knowledge, there is no data concerning the monitoring of BAC content in wet wipes. Another point at this stage, used detector in instrumental techniques is generally a mass spectrometer, which is very expensive and needs a qualifi ed person. Thus, this study aims to develop a simple, accurate, and reproducible analytical method for BAC monitoring in antibacterial wet wipes that does not require any sample pretreatment. For this purpose, the CE technique was used, since it is very powerful for separating alkyl halides, even with a UV detector. MATERIALS AND METHODS All chemicals used in experiments were of analytical or better grade. Standard material of BAC was purchased from Sigma-Aldrich Chemical Company (St. Louis, MO). Chemicals used for supporting electrolyte acetonitrile (ACN), methanol, disodium hydrogen phosphate, and sodium dihydrogen phosphate were also obtained from Sigma-Aldrich Chemical Company. Antibacterial wet wipe samples containing BAC, dry wipe tissues, and solution to wet wipe tissues were kindly supplied from Kardeşler Uçan Yag ˘lar Ltd. Ști (Gebze- KOCAELI,˙ Turkey). Properties of these wipe tissues were 40 g/m2 20% viscose 80% polyester. Ultrapure water (18.2 MW.cm at 25°C) was obtained by using Millipore Simplicity UV apparatus (Darmstad, Germany). pH measurements were made with Oakton pH 2100 Series digital pH-meter (Eutech Instruments, Singapore). Large-volume sample stacking CE technique was applied on an Agilent 3D Capillary Elec- trophoresis system (Germany) equipped with a diode array detector (DAD). Separation was achieved on an uncoated fused silica capillary, which was 75 μm I.D. and 47 cm in Figure 1. The molecular structure of BAC.