Optimization of solid-phase extraction of parabens and benzophenones in water samples using a combination of Plakett-Burman and Box-Behnken designs

On-site extraction of benzophenones from swimming pool water using hybrid tapes based on the integration of hydrophilic-lipophilic balance microparticles and an outer magnetic nanometric domain

An on-site extraction device is presented consisting of scotch tape modified with concentric domains of micrometric hydrophilic-lipophilic balance (HLB) particles surrounded by a ring of nanometric magnetic ones. On the one hand, HLB microparticles are readily available at the surface of the tape, exposed to interact with the target analytes, being responsible for the extraction capacity of the sorptive phase. On the other hand, the presence of magnetic nanoparticles enables the attachment of the modified tape onto a metallic screw via a magnet, which is then coupled to a wireless drill, enabling the stirring of the microextraction device. Both are simply fixed to the cost-effective, flexible, and versatile support, i.e., scotch tape, owing to their adhesive properties. The microextraction device has been applied to the determination of six benzophenones in swimming pool water samples. The variables that may affect the extraction process have been evaluated. Under the optimum conditions and using liquid chromatography-tandem mass spectrometry as the instrumental technique, the method provided a limit of detection of 0.03 µg L-1. The intra-day precision, evaluated at three different concentration levels and expressed as relative standard deviation, was lower than 10%, which also comprises the variability within single-use sorptive tapes. The accuracy, calculated with spiked samples and expressed as relative recovery, ranged from 71 to 138%. The method was applied to the analysis of swimming pool water, revealing the presence of such compounds.

Magnetic polyimide nanocomposite for analysis of parabens in cooking wine by magnetic solid-phase extraction coupled with gas chromatography - Mass spectrometry

A magnetic polyimide (PI) nanocomposite has been synthesized by phase inversion of PI and simultaneous encapsulation of Fe3O4 nanoparticles. The Fe3O4/PI nanocomposite was characterized by a variety of characterization techniques, including infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption isotherms, and vibrating sample magnetometry. The results showed that the prepared nanocomposite had a homogeneous structure, adequate specific surface area (76.1 m2/g) and high saturation magnetization (42.9 emu/g). Using parabens as model analytes, the performance of the Fe3O4/PI nanocomposite as an adsorbent for magnetic solid-phase extraction (MSPE) was evaluated. The extracted parabens were desorbed and determined by gas chromatography-mass spectrometry (GC-MS). The parameters affecting the extraction and desorption efficiency of parabens were optimized. Under the optimal conditions, the developed MSPE/GC-MS method was successfully applied to the determination of parabens in cooking wine. The MSPE/GC-MS method exhibited broad linearity (0.2-100 µg/L), low detection limits (0.04-0.05 µg/L), and satisfactory extraction recoveries (79.2 %-113.3 %) with relative standard deviations (RSDs) ranging from 0.7 % to 10.4 %. For real cooking wine samples, the spiked recoveries ranged from 91.7 % to 118.7 % with RSDs of 1.0 %-11.2 %. The results demonstrated that the Fe3O4/PI nanocomposite was an effective adsorbent, and this work provides a novel reference for the easy preparation of magnetic adsorbent materials.

Self-assembled Fe3O4-NH2 @g-C3N4 composite for magnetic solid-phase extraction of benzophenones in sea water and lake water coupled with LC-MS/MS determination

Magnetic solid-phase extraction (MSPE) was developed based on a well-designed Fe3O4-NH2 @g-C3N4 nanocomposite as sorbent for a mixture of six benzophenones (BPs) in environmental water samples. The composite fabricated via in-situ self-assembled g-C3N4 shell with homogeneous polymerization of cyanuric chloride and cyanuric acid on Fe3O4-NH2 core. While high adsorption capacity was derived from g-C3N4 via hydrophobic, π-π and hydrogen bonding interactions to the targets, the fast magnetic separation was realized with Fe3O4 core for less solvent consumption. In combination with LC-MS/MS, the Fe3O4-NH2 @g-C3N4 sorbent minimized the interfering components, reduced the matrix effects, and provided the enrichment factors of 121-150 for six BPs with relative standard deviations ≤ 9.7% even after 20 times extraction-desorption cycles. The present method gave the detection limits of 0.3-2.5 ng/L for six BPs with the linear ranges of 1.0-2000 ng/L, and the recoveries of 84.6%-104% in sea water and 86.2%-107% in lake water samples. Thus, the Fe3O4-NH2 @g-C3N4-based MSPE coupled with LC-MS/MS method provided a convenient, efficient, and reliable alternative to monitor trace BPs in environmental water samples.

Ultrasound- and Vortex-Assisted Dispersive Liquid-Liquid Microextraction of Parabens from Personal Care Products and Urine, Followed by High-Performance Liquid Chromatography

Objectives

Parabens, which are p-hydroxybenzoic acid esters, are used as preservatives in personal care products, pharmaceuticals, and food because of their antimicrobial activity. However, they are also classified as suspected endocrine disruptors and carcinogens. In the present study, we aimed to optimize an ultrasound and vortex-assisted dispersive liquid-liquid microextraction (DLLME) procedure for the simultaneous extraction of methyl, ethyl, isopropyl, propyl, isobutyl, and butyl parabens from personal care products and urine.

Materials and Methods

The extraction solvent type, extraction solvent volume, disperser solvent volume, sodium chloride concentration, ultrasonication time, and vortex application time were evaluated to obtain optimum recoveries by ultrasound and vortex-assisted DLLME. Parabens were detected using a validated high performanc-liquid chromatography (HPLC) method with fluorescence detection. Method validation was performed by examining linearity, the limit of detection, limit of quantification, accuracy, and precision.

Results

The limits of detection and quantification of the HPLC method were between 0.09-0.18 μg/mL and 0.28-0.54 μg/mL, respectively. Precision was examined as the relative standard deviation, which was 0.22-1.81% and 1.12-2.03% for intra- and interday studies. Recovery percentages were higher than 96.00%. Samples of two paraben-free personal care products and synthetic urine were spiked with the analyses at 0.02 μg/mL and were successfully analyzed using the developed procedure with recovery values higher than 82.00%.

Conclusion

The proposed procedure provided quantification of selected parabens at 20 ng/mL in analyzed personal care products and urine matrices with good precision and accuracy.

Application of Doehlert Experimental Design for Optimization of a New-Based Hydrophilic Interaction Solid-Phase Extraction of Phenolic Acids from Olive Oils

In this work, a rapid, precise, and cost-valuable method has been established to quantify phenolic compounds in olive oil using new-based hydrophilic interaction solid-phase extraction (SPE). Boehlert's experimental design applied the determination of the optimal operating conditions. An investigation into the effects of the methanol composition (50-100%), the volume of eluent (1-12 mL), and pH (1-3) on the extraction of phenols acids and total phenols from Tunisian olive oils was performed. The results showed that the extraction conditions had a significant effect on the extraction efficiency. The experiment showed that the greatest conditions for the SPE of phenolic acids were the methanol composition at 90.3%, pH at 2.9, and volume at 7.5 mL, respectively. The optimal conditions were applied to different types of olive oils, and it could be concluded that larger concentrations of polyphenols were found in extra virgin olive oil (89.15-218), whereas the lowest levels of these compounds (66.8 and 5.1) were found in cold-pressed crude olive oil and olive pomace oil, respectively.

Application of Response Surface Methodology to Optimize Solid-Phase Extraction of Benzoic Acid and Sorbic Acid from Food Drinks

An experimental design was applied for the optimization of the extraction process of two preservatives, benzoic and sorbic acids (BA, SA), from food drinks. A simple, rapid, and reliable solid-phase extraction (SPE) method for the simultaneous extraction of these two preservatives and their determination by liquid chromatography with a diode array detector was considered. Box−Behnken design (BBD) was applied to both steps of the SPE process: (i) the sample percolation to ensure the retention of the totality of the acids by the silica-based C18 sorbent; (ii) the elution step to ensure desorption of the totality of the acids from the cartridge. Thus, the volume, pH, and flow rate of the sample, and the percentage of MeOH, volume, and flow rate of the elution solvent, were optimized. Sample volume and pH have a significant influence (p < 0.0001 and p = 0.0115) on the percolation yield. However, no effect was recorded for the flow rate (p > 0.05). Flow rate also has no significant effect on the elution efficiency. The proposed new solid-phase extraction method, which can be easily applied to routine monitoring of preservatives BA and SA in juice and soft drink samples, included 0.5 g of C18 sorbent, 1 mL of food drink adjusted to pH 1 and percolated at 4.5 mL min−1, and 1 mL of a solvent mixture composed of methanol/acidified water (pH = 2.6) (90:10, v/v) used in the elution step at a flow rate of 4.5 mL min−1. Validation of the SPE method and the technique of analysis were evaluated, namely, the accuracy, precision, detection, and quantification limits and linearity. Recovery percentages of benzoic and sorbic acids were above 95% with relative standard deviations lower than 1.78%. Detection and quantification limits were 0.177 and 0.592 µg mL−1, and 0.502 and 0.873 µg mL−1 for benzoic acid and sorbic acid respectively. Optimal conditions were applied to commercial fruit juices and soft drinks and a minimal matrix effect was observed. This method was compared with other SPE methods using oxidized activated carbon and multiwalled carbon nanotubes as adsorbents. The yields determined with these last two were low compared to those determined with our method.

Chitosan-Ni/Fe layered double hydroxide composites as an efficient solid phase extraction sorbent for HPLC-PDA monitoring of parabens in personal care products

There is a dire need for development of efficient and sensitive methods to efficiently screen parabens. In this research, we focused on quantification of four parabens (i.e., methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butyl paraben (BP)) using chitosan intercalated nickel/iron layered double hydroxide (CS-Ni/Fe-LDH) composites as solid phase extraction sorbent prior to HPLC-PDA analysis. CS-Ni/Fe LDH composites with a heterogeneous, porous texture, and coral reef-like structure exhibit appealing extraction efficiency for the target parabens due to the enhanced possibility for the formation of hydrogen bonding and hydrophobic interactions. The performance of the composites was assessed and optimized for solid phase extraction of parabens from standard samples and real samples (rose water, cream, toothpaste, hair serum, and sunscreen). The LDH-SPE-HPLC method exhibited a wide linear range (e.g., 100-50,000 ng L^-1), good linearity (R² ≥ 0.999), and good precision (relative standard deviation (RSD) < 3%). This method successfully enriched selected parabens with remarkable recovery above 85.95% and a good RSD (0.01-2.90%). The quantitation of MP, EP, PP, and BP was made at detection range (and limits of detection (LOD)) of 5-15 (9.8), 11-21 (16.2), 6-18 (12.4), and 10-20 (15.6) ng L^-1, respectively. The prepared composites also displayed excellent performance with enhanced reusability/durability (n = 30 cycles) and reproducibility (n = 5).

The experimental design approach to the optimization of a simple quick easy cheap effective rugged and safe method for the analysis of phytoestrogens in complex soy-based food

The present paper deals with the multivariate optimization of an extraction-purification strategy for the determination of phytoestrogens (daidzein, genistein, coumestrol, formononetin, and biochanin A) in soy-based meat substitutes by high performance liquid chromatography with tandem mass spectrometry. For a reliable quantitation of these new concerning compounds in such a complex matrix, recovery and matrix effect must be carefully evaluated. Therefore, two sequential experimental designs were used to optimize the sample-pretreatment of soy-based burgers: the chosen technique was the quick, easy, cheap, effective, rugged and safe methodology, which does not require any particular facility or instrumentation. Thanks to the first screening design (Plackett-Burman), the significant factors influencing the studied responses were identified and further investigated through a response surface design (Box-Behnken). The optimal values of the variables (volume of extraction solvent mix/sample mass ratio and two clean-up sorbents) led to quantitative recoveries (97-104%) and low ion suppression (matrix effect 60-93%) for all analytes. This optimized method was characterized by low detection limits (0.2-1.5 ng/g) and excellent intraday precision (RSD 2-4%). It was applied to the determination of the considered compounds in several soy-burgers from the Italian market, detecting low ng/g levels (up to 40 ng/g) of coumestrol, formononetin, and biochanin A, and high concentrations (7.9-78 µg/g) of genistein and daidzein.