Development of a Green Alternative Vortex-Assisted Dispersive Liquid–Liquid Microextraction Based on Natural Hydrophobic Deep Eutectic Solvents for the Analysis of Phthalate Esters in Soft Drinks

Abstract

A new green alternative vortex-assisted dispersive liquid−liquid microextraction method based on a natural hydrophobic deep eutectic solvent was developed for the extraction of 14 phthalic acid esters and one adipate in cold infusions and tonic waters. Analyses were carried out using ultra-performance liquid chromatography coupled to tandem mass spectrometry. Different eutectic mixtures based on the monoterpene thymol (essential oil of thyme) and medium-chain fatty acids (octanoic and decanoic acids) at different molar ratios were tested in this regard. The effect of different factors affecting extraction efficiency was optimized through a systematic approach. The method was validated by means of precision, matrix-matched calibration, recovery, and repeatability studies using two different deuterated surrogate standards (dibutyl phthalate-3,4,5,6-d 4 and dihexyl phthalate-3,4,5,6-d 4 ). The method proved to be linear (determination coefficients were higher than 0.9912) with normalized recoveries in the range between 71 and 124% (except for di-n-octyl phthalate at a low concentration level in tonic water [63%]). Then, the method was applied for the analysis of the selected compounds in 3 pineapple/green tea-based cold infusions and 8 tonic beverages. Finally, the greenness of the procedure was assessed using the Analytical Eco-Scale. This paper represents the first application of this natural hydrophobic deep eutectic solvent for the analysis of phthalate esters, and, also the first time, these compounds are analyzed in cold infusion and tonic water.

Application of a Liquid-Liquid Microextraction Method Based on a Natural Hydrophobic Deep Eutectic Solvent for the Extraction of Plastic Migrants from Kombuchas

“…Since the objective of this work is to check the presence of PAEs residues in kombuchas, those samples presenting one of these compounds were also analyzed with a UHPLC-MS/MS instrument using the conditions described by Santana-Mayor et al [ 9 ]. Those conditions are included in Section 3.2 .…”

“…The NaHDES Th:OctA 2:1 was previously employed in our laboratory [ 9 ] for the extraction of a similar group of PAEs from tonic water and cold infusion with good results. Therefore, it is a promising protocol for the analysis of other beverages.…”

“…Although the first DESs used had a hydrophilic character, the introduction of hydrophobic DESs (HDESs) [ 7 ] was a real revolution because of their compatibility with aqueous samples without the need for extra reagents. In fact, NaHDESs have proven to be an interesting alternative in different analytical applications [ 7 , 8 , 9 ]. It should be mentioned that, despite their inherent advantages, it has been proved [ 10 , 11 ] that the toxicity of certain DESs is higher than the aqueous solutions of the constituents due to a disruption effect on cell walls.…”

“…Therefore, hundreds of analytical protocols have been developed for the analysis of these compounds in foods [ 18 ]. In this regard, the use of DESs has promoted new sustainable protocols [ 8 , 9 , 19 , 20 , 21 ]. We have recently developed a NaHDES based on thymol (Th):octanoic acid (OctA) (molar ratio 2:1) for vortex-assisted liquid-liquid microextraction (VA-LLME) of PAEs from tonic water (bottled in plastic, glass and metal containers) and cold infusions [ 9 ].…”

“…In this regard, the use of DESs has promoted new sustainable protocols [ 8 , 9 , 19 , 20 , 21 ]. We have recently developed a NaHDES based on thymol (Th):octanoic acid (OctA) (molar ratio 2:1) for vortex-assisted liquid-liquid microextraction (VA-LLME) of PAEs from tonic water (bottled in plastic, glass and metal containers) and cold infusions [ 9 ]. For this purpose, factors affecting extraction efficiency (i.e., type and proportions of NaHDES components, sample pH and NaHDES volume) were optimized using a univariate protocol.…”