Juan L. Benedé

Sunscreen Products as Emerging Pollutants to Coastal Waters

A growing awareness of the risks associated with skin exposure to ultraviolet (UV) radiation over the past decades has led to increased use of sunscreen cosmetic products leading the introduction of new chemical compounds in the marine environment. Although coastal tourism and recreation are the largest and most rapidly growing activities in the world, the evaluation of sunscreen as source of chemicals to the coastal marine system has not been addressed. Concentrations of chemical UV filters included in the formulation of sunscreens, such as benzophehone 3 (BZ-3), 4-methylbenzylidene camphor (4-MBC), TiO2 and ZnO, are detected in nearshore waters with variable concentrations along the day and mainly concentrated in the surface microlayer (i.e. 53.6–577.5 ng L-1 BZ-3; 51.4–113.4 ng L-1 4-MBC; 6.9–37.6 µg L-1 Ti; 1.0–3.3 µg L-1 Zn). The presence of these compounds in seawater suggests relevant effects on phytoplankton. Indeed, we provide evidences of the negative effect of sunblocks on the growth of the commonly found marine diatom Chaetoceros gracilis (mean EC50 = 125±71 mg L-1). Dissolution of sunscreens in seawater also releases inorganic nutrients (N, P and Si forms) that can fuel algal growth. In particular, PO4 3− is released by these products in notable amounts (up to 17 µmol PO4 3− g−1). We conservatively estimate an increase of up to 100% background PO4 3− concentrations (0.12 µmol L-1 over a background level of 0.06 µmol L-1) in nearshore waters during low water renewal conditions in a populated beach in Majorca island. Our results show that sunscreen products are a significant source of organic and inorganic chemicals that reach the sea with potential ecological consequences on the coastal marine ecosystem.

Determination of UV filters in both soluble and particulate fractions of seawaters by dispersive liquid–liquid microextraction followed by gas chromatography–mass spectrometry

An analytical method to determine the total content (i.e., not only in the soluble fraction but also in the particulate one) of eight commonly used UV filters in seawater samples is presented for the first time. Dispersive liquid-liquid microextraction (DLLME) is used as microextraction technique to pre-concentrate the target analytes before their determination by gas chromatography-mass spectrometry (GC-MS). In order to release the UV filters from the suspended particles an ultrasound treatment is performed before DLLME. The ultrasound treatment time was studied in order to achieve a quantitative lixiviation of the target analytes. The type and volume of both disperser and extraction solvent, the sample volume, the pH and the ionic strength involved in the DLLME have been optimized to provide the best enrichment factors. Under the optimized conditions, the method was successfully validated showing good linearity, enrichment factors between 112 and 263 depending on the analyte, limits of detection and quantification in the low ng L(-1) range (10-30 ng L(-1) and 33-99 ng L(-1), respectively) and good intra- and inter-day repeatability (RSD <15%). No significant matrix effects were found. Finally, the method was satisfactorily applied to the analysis of three seawater samples from different origin. Results showed significant amounts of UV filters in the particulate fraction that would have been ignored if only the soluble fraction had been considered. This fact shows that the UV filters are also accumulated in the suspended particles contained in water, what should be taken into account from an environmental standpoint.

Development of stir bar sorptive-dispersive microextraction mediated by magnetic nanoparticles and its analytical application to the determination of hydrophobic organic compounds in aqueous media

A novel microextraction technique combining the principles of stir bar sorptive extraction (SBSE) and dispersive micro-solid phase extraction (DμSPE) is presented. The main feature of the method is the use of a neodymium-core stirring bar physically coated with a hydrophobic magnetic nanosorbent. Depending on stirring speed, the magnetic sorbent either acts as a coating material to the stir bar, thus affording extraction alike SBSE, or as a dispersed nanosorbent medium for the collection and extraction of the target analytes, in close analogy to DμSPE. Once the stirring process is finished, the strong magnetic field of the stir bar prevails again and rapidly retrieves the dispersed MNPs. Alike SBSE, the stir bar is collected and the analytes are back-extracted by liquid desorption into an appropriate organic solvent, which is used for analysis. This enrichment technique is easy to prepare since it does not require special surface modification procedures, uses low volumes of non-toxic organic solvents and most importantly imbues SBSE with additional functionalities against a wide range of analytes (since nanosorbents with various coatings can be employed) while it affords additional merits to DμSPE in terms of extraction and post-extraction treatment. As proof-of-concept this new approach was applied to the determination of organic UV filters in seawater samples using oleic acid-coated cobalt ferrite (CoFe2O4@oleic acid) magnetic nanoparticles as sorbent material. The method showed good analytical features in terms of linearity, enrichment factors (11-148), limits of detection (low ngmL(-1)), intra- and inter-day repeatability (RSD<11%) and relative recoveries (87-120%).

Introducing a new and rapid microextraction approach based on magnetic ionic liquids: Stir bar dispersive liquid microextraction

With the aim of contributing to the development and improvement of microextraction techniques, a novel approach combining the principles and advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) is presented. This new approach, termed stir bar dispersive liquid microextraction (SBDLME), involves the addition of a magnetic ionic liquid (MIL) and a neodymium-core magnetic stir bar into the sample allowing the MIL coat the stir bar due to physical forces (i.e., magnetism). As long as the stirring rate is maintained at low speed, the MIL resists rotational (centrifugal) forces and remains on the stir bar surface in a manner closely resembling SBSE. By increasing the stirring rate, the rotational forces surpass the magnetic field and the MIL disperses into the sample solution in a similar manner to DLLME. After extraction, the stirring is stopped and the MIL returns to the stir bar without the requirement of an additional external magnetic field. The MIL-coated stir bar containing the preconcentrated analytes is thermally desorbed directly into a gas chromatographic system coupled to a mass spectrometric detector (TD-GC-MS). This novel approach opens new insights into the microextraction field, by using the benefits provided by SBSE and DLLME simultaneously, such as automated thermal desorption and high surface contact area, respectively, but most importantly, it enables the use of tailor-made solvents (i.e., MILs). To prove its utility, SBDLME has been used in the extraction of lipophilic organic UV filters from environmental water samples as model analytical application with excellent analytical features in terms of linearity, enrichment factors (67-791), limits of detection (low ng L-1), intra- and inter-day repeatability (RSD<15%) and relative recoveries (87-113%, 91-117% and 89-115% for river, sea and swimming pool water samples, respectively).

A rapid and sensitive gas chromatography-mass spectrometry method for the quality control of perfumes: simultaneous determination of phthalates

A rapid and sensitive analytical gas chromatography-mass spectrometry (GC-MS) method for perfume analysis to determine the phthalates banned by the European Union Regulation on cosmetic samples is presented. This method has been tested in commercial alcoholic perfume samples for the determination of the following seven phthalates: dibutyl phthalate, bis(2-ethylhexyl) phthalate, bis(2-methoxyethyl) phthalate, n-pentyl-isopentylphthalate, di-n-pentyl phthalate, diisopentylphthalate and benzyl butyl phthalate. Sample evaporation and redissolution in ethanol is carried out before GC-MS analysis, with no dilution of the sample. External calibration and standard addition calibration are compared to detect possible matrix effects. External calibration could provide good results in some cases but standard addition calibration is recommended as matrix effects are observed in many cases in the determination of the target phthalates. The accuracy of the method has been proven by the analysis of quality control samples prepared from commercial free phthalate perfumes after spiking with known concentrations of the analytes. Accurate results were obtained with limits of detection in the ng mL−1 range and good repeatability (relative standard deviations lower than 6%). The method was satisfactorily applied to the analysis of commercial perfume samples, and the results revealed considerable amounts of dibutyl phthalate and bis(2-ethylhexyl) phthalate in some of the analyzed samples.

Determination of ultraviolet filters in bathing waters by stir bar sorptive–dispersive microextraction coupled to thermal desorption–gas chromatography–mass spectrometry

In this work, a new approach that combines the advantages of stir bar sorptive extraction (SBSE) and dispersive solid phase extraction (DSPE), i.e. stir bar sorptive-dispersive microextraction (SBSDµE), is employed as enrichment and clean-up technique for the sensitive determination of eight lipophilic UV filters in water samples. The extraction is accomplished using a neodymium stir bar magnetically coated with oleic acid-coated cobalt ferrite magnetic nanoparticles (MNPs) as sorbent material, which are detached and dispersed into the solution at high stirring rate. When stirring is stopped, MNPs are magnetically retrieved onto the stir bar, which is subjected to thermal desorption (TD) to release the analytes into the gas chromatography-mass spectrometry (GC-MS) system. The SBSDµE approach allows for lower extraction time than SBSE and easier post-extraction treatment than DSPE, while TD allows for an effective and solvent-free injection of the entire quantity of desorbed analytes into GC-MS, and thus achieving a high sensitivity. The main parameters involved in TD, as well as the extraction time, were evaluated. Under the optimized conditions, the method was successfully validated showing good linearity, limits of detection and quantification in the low ngL(-1) range and good intra- and inter-day repeatability (RSD<12%). This accurate and sensitive analytical method was applied to the determination of trace amounts of UV filters in three bathing water samples (river, sea and swimming pool) with satisfactory relative recovery values (80-116%).

Trace determination of volatile polycyclic aromatic hydrocarbons in natural waters by magnetic ionic liquid-based stir bar dispersive liquid microextraction.

In this work, a novel hybrid approach called stir bar dispersive liquid microextraction (SBDLME) that combines the advantages of stir bar sorptive extraction (SBSE) and dispersive liquid-liquid microextraction (DLLME) has been employed for the accurate and sensitive determination of ten polycyclic aromatic hydrocarbons (PAHs) in natural water samples. The extraction is carried out using a neodymium stir bar magnetically coated with a magnetic ionic liquid (MIL) as extraction device, in such a way that the MIL is dispersed into the solution at high stirring rates. Once the stirring is ceased, the MIL is magnetically retrieved onto the stir bar, and subsequently subjected to thermal desorption (TD) coupled to a gas chromatography-mass spectrometry (GC-MS) system. The main parameters involved in TD, as well as in the extraction step affecting the extraction efficiency (i.e., MIL amount, extraction time and ionic strength) were evaluated. Under the optimized conditions, the method was successfully validated showing good linearity, limits of detection and quantification in the low ng L-1 level, good intra- and inter-day repeatability (RSD < 13%) and good enrichment factors (18 - 717). This sensitive analytical method was applied to the determination of trace amounts of PAHs in three natural water samples (river, tap and rainwater) with satisfactory relative recovery values (84-115%), highlighting that the matrices under consideration do not affect the extraction process.

In-situ suspended aggregate microextraction: A sample preparation approach for the enrichment of organic compounds in aqueous solutions

This work presents in-situ suspended aggregate microextraction (iSAME) as a new and expedient sample preparation method. This new concept capitalizes on the general principles of in-situ solvent formation microextraction, in the sense that extraction is carried out in a supramolecular aggregate phase, which is formed in-situ in the sample through one-step process involving ion-association between a cationic surfactant and a benzene sulfonic acid derivative. The suspended aggregate containing the analytes is then collected in the form of a thin-film on the surface of a common filter paper by suction filtration. The entrapped analytes are released by completely dissolving the thin-film with a small volume of an organic solvent which is used for analysis. Using a series of organic UV filters as model analytes, the experimental variables pertaining to the operation of this new extraction approach were optimized and validated to the analysis of genuine water samples of different nature and with different matrix complexity (tap, river, lake, lagoon, delta and sea). The satisfactory analytical performance of the method in terms of recovery rates (80-112%), precision (0.9-11.5%), high linearity of the calibration curves over a concentration range of 3 orders of magnitude, the high selectivity along with its simplicity and low resource requirements render the method as an attractive alternative to the routine assessment of organic compounds in environmental water samples.

Environmental Monitoring of Cosmetic Ingredients

Abstract Since the late 1990s there has been an increasing concern regarding the release and accumulation of cosmetic ingredients in the environment. These compounds reach the aquatic environment by direct sources, such as bathing activities, but also by indirect sources due to industrial activities, showering, domestic washing, etc., through wastewater treatment plants at which they are not completely removed. As a result, studies have shown that cosmetic ingredients can be found not only in the water phase but also in sediments, soils and living organisms, thus affecting the flora and fauna of the aquatic environment. In this chapter, the fundamental principles of sample preparation methodologies and detection techniques developed for the extraction of cosmetic ingredients from environmental samples are discussed, and a comprehensive outline of the literature dealing with the development and validation of analytical methods for the determination of these emerging contaminants in the environment is provided.

Determination of N-nitrosodiethanolamine in cosmetic products by reversed-phase dispersive liquid-liquid microextraction followed by liquid chromatography

A new analytical method for the determination of N-nitrosodiethanolamine (NDELA), a very harmful compound not allowed in cosmetic products, is presented. The method is based on a new approach of dispersive liquid-liquid microextraction (DLLME) useful for extraction of highly polar compounds, called reversed-phase DLLME (RP-DLLME), followed by liquid chromatography-ultraviolet/visible (LC-UV/Vis) determination. The variables involved in the RP-DLLME process were studied to provide the best enrichment factors. Under the optimized conditions, a mixture of 750µL of acetone (disperser solvent) and 125µL of water (extraction solvent) was rapidly injected into 5mL of toluene sample solution. The extracts were injected into the LC-UV/Vis system using ammonium acetate 0.02M as mobile phase. After chromatographic separation, the eluate passed throughout a photolysis unit in order to convert NDELA to nitrite, and then it was merged with a flow stream of Griess Reagent and passed throughout a post-column reactor at 50°C to derivatize nitrite into an azo-dye, which was finally measured spectrophotometrically at 540nm. The method was successfully validated showing good linearity, an enrichment factor of 31.5±0.9, limits of detection and quantification of 1.1 and 3.6ngmL-1, respectively, and a good repeatability (RSD <8%). Finally, the proposed analytical method was applied to the determination of NDELA in commercial cosmetic samples of different nature, specifically three lipophilic creams and a hydrophilic shower gel, with good relative recovery values (87 - 117%) thus showing that matrix effects are negligible. These results were compared with those obtained by applying the ISO 10130 official method, which uses the same detection approach. It was concluded that a great improvement in the sensitivity was achieved, whereas the use of organochlorine solvents is avoided and therefore it can be considered as a greener approach.