Determination of six parabens in biological samples by magnetic solid-phase extraction with magnetic mesoporous carbon adsorbent and UHPLC-MS/MS

Quantification of parabens in marine fish samples by a rapid, simple, effective sample preparation method

Parabens (p-hydroxybenzoic acid esters) commonly used preservatives (in cosmetics, pharmaceuticals, and foods) can pose potential effects on environmental health. In this study, seven parabens were quantified in marine fish samples using an ultra-high performance liquid chromatography triple quadrupole mass spectrometer (UHPLC-MS/MS) system. Parabens in the fish samples were extracted and purified by a rapid, simple, and effective procedure comprising sample homogenization with solvent, solid-phase extraction clean-up, and solvent evaporation. Results demonstrated that the recoveries of seven compounds (with relative standard deviation < 15%) were 88-103% in matrix-spike samples and 86-105% in surrogate standards. The method detection limits and method quantification limits of seven parabens were 0.015-0.030 and 0.045-0.090 ng/g-ww (wet weight), respectively. The optimized method was applied to measure the concentration of parabens in the 37 marine fish samples collected from Vietnam coastal waters. The concentration ranges of seven parabens found in round scad and greater lizardfish samples were 6.82-25.3 ng/g ww and 6.21-17.2 ng/g-ww, respectively. Among parabens, methylparaben accounted for the highest contribution in both fish species (43.2 and 44.9%, respectively). Based on the measured concentrations of parabens in marine fish samples, the estimated daily intake was calculated for children and adults with the corresponding values of 0.0477 µg/kg/day and 0.0119 µg/kg/day, respectively. However, the presence of parabens in Vietnamese marine fish may not pose a significant risk to human health.

Selective and fast magnetic dispersive solid phase micro-extraction of copper and lead in water and vegetables after synthesis of magnetic mesoporous carbon

Magnetic mesoporous carbon (Fe3O4@C, MMC) was synthesized and characterized. It was used for the first time as a sorbent for the magnetic dispersive solid phase microextraction (M-dSPμE) of copper and lead in water and vegetables. FAAS was used to determine the analyte concentrations after elution. The MMC was found to be have surface area of 145.9 m2 g-1 and average pore diameter of 15 nm. The analytical parameters affecting M-dSPμE of copper and lead were optimized. They were pH of sample, 6; eluent, 2 mol L-1 HCl (3 mL); and sample volume, 250 mL. The MMC reaches equilibrium very fast without vortexing for adsorption and only 5 s for elution. The LOD and PF of the M-dSPμE method for copper and lead were found to be 0.87 μg L-1 and 83 for Cu(II) and 2.8 μg L-1 and 167 for Pb(II), respectively. The precision of the M-dSPμE method was found to be ≤ 3.2%. The M-dSPμE method was verified by certificate reference materials (TMDA-53.3 Fortified Lake water and NIST SRM 1573a Tomato Leaves). It was successfully applied to the determination of copper and lead in lake water, wastewaters, sea water, radish, spinach, lettuce, and celery samples.

Determination of Parabens and Their Metabolites in Seminal Plasma from Chinese Men by Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS/MS)

Parabens are endocrine-disrupting chemicals (EDCs) that have estrogen-like activities and may cause male reproductive disorders. Here, we developed a method for the simultaneous determination of four parabens (MeP, EtP, n-PrP, n-BuP) and two metabolites (4-HB and 3,4-DHB) in human seminal plasma by UPLC-MS/MS. The method was used to analyze 144 seminal plasma samples from Chinese males. MeP, EtP, n-PrP, and 4-HB were the dominant compounds. MeP, EtP, and n-PrP were significantly correlated to each other. In addition, 4-HB was significantly correlated to MeP, EtP, n-PrP, and 3,4-DHB, respectively. The results provide direct evidence that parabens and their metabolites are widely distributed in the male reproductive system. The study presents the paraben metabolites levels in human seminal plasma for the first time.

Fabrication of magnetic covalent organic framework for effective and selective solid-phase extraction of propylparaben from food samples

Efficient magnetic solid phase extraction using crystalline porous polymers can find important applications in food safety. Herein, the core-shell Fe₃O₄@COFs nanospheres were synthesized by one-pot method and characterized in detail. The porous COF shell with large surface area had fast and selective adsorption for propylparaben via π-π, hydrogen bonding and hydrophobic interactions. The extraction and desorption parameters were evaluated in detail. Under the optimized conditions, the extraction equilibrium was reached only in 5 min, the maximum adsorption capacity for propylparaben was 500 mg g^-1 and the proposed Fe₃O₄@DhaTab-based-MSPE-HPLC-UV method afforded good linearity (4-20000 μg mL^-1) with R² (0.997), low limits of detection (0.55 μg L^-1) and limits of quantification (1.5 μg L^-1). Furthermore, the developed method was applied to determine propylparaben in soft drinks with the recoveries (97.0-98.3%) and relative standard deviations (0.61 to 3.75%). These results revealed the potential of Fe₃O₄@DhaTab as efficient adsorbents for parabens in food samples.

Core-shell-structured magnetic covalent organic frameworks for effective extraction of parabens prior to their determination by HPLC

Covalent organic framework (COF)-decorated magnetic nanoparticles (Fe₃O₄@DhaTab) with core-shell structure have been synthesized by one-pot method. The prepared Fe₃O₄@DhaTab was well characterized, and parameters of magnetic solid-phase extraction (MSPE) for parabens were also investigated in detail. Under optimized conditions, the adsorbent dosage was only 3 mg and extraction time was 10 min. The developed Fe₃O₄@DhaTab-based MSPE-HPLC analysis method offered good linearity (0.01-20 μg mL^-1) with R² (0.999) and low limits of detection (3.3-6.5 μg L^-1) using UV detector at 254 nm. The proposed method was applied to determine four parabens in environmental water samples with recoveries in the range 64.0-105% and relative standard deviations of 0.16-7.8%. The adsorption mechanism was explored and indicated that porous DhaTab shell provided π-π, hydrophobic, and hydrogen bonding interactions in the MSPE process. The results revealed the potential of magnetic-functionalized COFs in determination of environmental contaminants.

Dispersive magnetic solid phase microextraction on microfluidic systems for extraction and determination of parabens

In this study, a customized microfluidic system was utilized for magnetic solid phase extraction of parabens. For this sake, magnetite nanoparticles were synthesized and coated with polyaniline to enable efficient extraction and magnetic separation of sorbents particles. The synthesized particles were extensively characterized in terms of morphology, composition, and magnetic properties. The utilized microfluidic platform consisted of a relatively long spiral microchannel fabricated through laser-cutting and multi-layered assembly. To obtain an efficient dispersion, simultaneous flows of sample solution and magnetic beads dispersion were introduced to the chip with the aid of two syringe pumps. In order to increase the stability of the dispersed nanoparticles in the aqueous solution, various chemical and instrumental parameters were investigated and optimized. In this context, exploitation of hydrophobic surfactants and surface charge manipulation of the particles was shown to be a highly promising approach for effective dispersion and maintenance of magnetic beads in long microfluidic channels. Under the optimized conditions, the calibration curves were linear in the range of 5.0-1000.0 μg L^-1 for propyl paraben and 8.0-1000.0 μg L^-1 for methyl- and ethyl paraben with coefficients of determination greater than 0.992. Relative standard deviations were assessed as intra- and inter-day values which were less than 7.2% and the preconcentration factors in water were 10-15 for 100 μg L^-1 of parabens in water. Finally, the method was applied for the extraction of parabens from fruit juice, sunscreen, and urine samples which showed favorable accuracy and precision.