**1. Introduction**

Ultraviolet filters are chemical agents that are used in a variety of cosmetics, specifically those used for sun protection such as sunscreen lotions, creams and sprays [1]. These compounds often contain single or multiple aromatic structures (**Figure 1**), sometimes conjugated with

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Thus the aim of this study was to develop a multivariate assisted solid phase extraction method for the simultaneous preconcentration of UV- filters in wastewater samples prior to their spectrophotometric quantification. The main advantage of the method relies on the use of multivariate optimization approach which led to the reduction of the number of experiments and analysis time as well as the use of a simple, fast and cost effective instrumentation. UV-Vis spectrophotometry was chosen due its simplicity and high availability. The factors (such as sample pH, flow rates, eluent and adsorbent types) affecting the preconcentration step method were optimized using univariate and multivariate approach. The developed SPE/spectrophometric method was applied to the preconcentration and determination of two UV filters from the wastewater samples collected from Daspoort wastewater treatment plant (WWTP) in Pretoria, Gauteng, South Africa. According to our literature search there are limited reports on the application of UV-Vis spectrophotometry for quantification of UV filters [29]. In addition, to the best of our knowledge, the application of SPE/UV-Vis spectrophotometry for simultaneous preconcentration and determination of Benzophenone and sulisoben-

Multivariate-Assisted Solid Phase Extraction Procedure for Simultaneous Preconcentration…

http://dx.doi.org/10.5772/intechopen.75641

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Benzophenone (Reagent plus, 99%), sulisobenzone (5-benzoyl-4-hydroxy-2-methoxy-benzenesulfonic acid) (HPLC, ≥97.0%) and acetonitrile (for HPLC Plus) were purchased from Sigma-Aldrich (St. Louis, MO, USA). Ethyl acetate was purchased from Merck (Merck, Darmstadt, Germany), ethanol and methanol were purchased from Associated Chemical Enterprises (Johannesburg, South Africa). Stock solutions of benzophenone and 5-benzoyl-4-hydroxy-2-methoxy-benzenesulfonic acid (10 mg L−1) were prepared in ultra-pure water (Direct-Q® 3UV-R purifier system, Millipore, Merck). Working standards of 100 μg L−1 were prepared daily by diluting appropriate volumes of the stock solution in ultra-pure water. The ion exchange resins used in this study as packing materials were Dowex 1x8 (Chloride form)

A Shimadzu UV-2450 high performance single monochromator UV-VIS spectrophotometer (Shimadzu Corporation, Tokyo, Japan) was used for all analysis of the samples. Solid phase extraction (SPE) was carried out in a VacMaster-24 sample SPE station (VacMaster, Biotage, Sweden). The latter was used to control the sample loading and elution flow rate in the range of 1–3.0 mL min−1. An OHAUS starter 2100 pH meter (Pine Brook, NJ, USA) was used for pH

Influent (after sediment removal) and effluent wastewater samples were collected from Daspoort wastewater treatment plant (WWTP, Pretoria, Gauteng, south Africa). The samples were collected in pre-cleaned 500 mL glass bottles. The samples were then refrigerated at 4°C.

adjustments of the reagents and to measure the pH of samples

zone has been reported for the first time.

**2. Experimental**

(Sigma Aldrich).

**2.2. Instrumentation**

**2.3. Sampling and sample collection**

**2.1. Materials and reagents**

**Figure 1.** Chemical structures of (a) benzophenone and (b) sulisobenzone.

carbon-carbon double bonds and carbonyl moieties [2]. The presence of these functional groups affords UV filters the ability to absorb photons and rapidly return to the ground state by thermally emitting the energy through vibrational relaxation [3]. This makes the compound to be able to mitigate the deleterious effects of UV radiation [1, 2].

After application, UV-filters are washed off and enter the aquatic environmental directly or indirectly via wastewater effluent and recreational water systems [4]. They are also used as sun blocking agents in materials such as plastics, adhesive and rubber, this suggests that these compounds can also leach into the environmental matrices [5–7]. The amount and type of UV-filter used depends on the desired degree of protection, however combined concentrations should not exceed 10% with other organic or inorganic UV-filters [8].

The main concern of the presence of these compounds is their potential toxicity and their effects as xenohormones (effect on reproductive activity) [9, 10]. These effects include estrogenic activity [11], effects on cell proliferation by 4-methylbenzylidene camphor (4-MBC), benzophenones, and octyl methoxycinnamate (OMC) [12]. Several studies have shown hormonal disruption in both in vivo and in vitro test systems in fish and mammals [13–16]. It has also been recently shown that besides estrogens, there are other hormonal targets affected by UV-filters in fish and mammals [17, 18].

A number of detection techniques have been used to quantify UV-filters in environmental water samples. These include techniques high performance liquid chromatography (HPLC) with UV or mass spectrometry detection [19, 20], HPLC-MS/MS [21], gas chromatography-mass spectrometry (GC-MS) and GC-MS/MS [22, 23]. However, the levels of these compounds in environmental waters are usual in the μg L−1 range. Therefore, sample cleanup/preconcentration techniques such stir-bar sorptive extraction [20], pressurised liquid extraction [1], dispersive liquid-liquid phase extraction [24], solid phase extraction [25], among others, have been used to improve sensitivity, LODs and to remove interferences prior to quantification with the different analytical techniques.

Solid phase extraction is one of the most established preconcentration techniques used for the simultaneous extraction and analysis of organic compounds [26]. Mainly silica bonded phases such as C18 were formerly used for SPE, however recently modified and tuned solid phases can be used to achieve more specificity [27]. Advantages of SPE include the potential of simultaneous extraction, reduced labour and cost. Of the advantages of solid phase extraction, scientists are mostly attracted to the possibility of using reduced amount of organic solvents and the fact that SPE is highly tuneable with regards to the adsorbents used [28].

Thus the aim of this study was to develop a multivariate assisted solid phase extraction method for the simultaneous preconcentration of UV- filters in wastewater samples prior to their spectrophotometric quantification. The main advantage of the method relies on the use of multivariate optimization approach which led to the reduction of the number of experiments and analysis time as well as the use of a simple, fast and cost effective instrumentation. UV-Vis spectrophotometry was chosen due its simplicity and high availability. The factors (such as sample pH, flow rates, eluent and adsorbent types) affecting the preconcentration step method were optimized using univariate and multivariate approach. The developed SPE/spectrophometric method was applied to the preconcentration and determination of two UV filters from the wastewater samples collected from Daspoort wastewater treatment plant (WWTP) in Pretoria, Gauteng, South Africa. According to our literature search there are limited reports on the application of UV-Vis spectrophotometry for quantification of UV filters [29]. In addition, to the best of our knowledge, the application of SPE/UV-Vis spectrophotometry for simultaneous preconcentration and determination of Benzophenone and sulisobenzone has been reported for the first time.
