Elif Tümay Özer

Removal of diethyl phthalate from aqueous phase using magnetic poly(EGDMA–VP) beads

The barium hexaferrite (BaFe(12)O(19)) containing magnetic poly(ethylene glycol dimethacrylate-vinyl pyridine), (mag-poly(EGDMA-VP)) beads (average diameter=53-212 μm) were synthesized and characterized. Their use as an adsorbent in the removal of diethyl phthalate (DEP) from an aqueous solution was investigated. The mag-poly(EGDMA-VP) beads were prepared by copolymerizing of 4-vinyl pyridine (VP) with ethylene glycol dimethacrylate (EGDMA). The mag-poly(EGDMA-VP) beads were characterized by N(2) adsorption/desorption isotherms (BET), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), elemental analysis, scanning electron microscope (SEM) and swelling studies. At a fixed solid/solution ratio, the various factors affecting the adsorption of DEP from aqueous solutions such as pH, initial concentration, contact time and temperature were analyzed. The maximum DEP adsorption capacity of the mag-poly(EGDMA-VP) beads was determined as 98.9 mg/g at pH 3.0, 25°C. All the isotherm data can be fitted with both the Langmuir and the Dubinin-Radushkevich isotherm models. The pseudo first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models were used to describe the adsorption kinetics. The thermodynamic parameters obtained indicated the exothermic nature of the adsorption. The DEP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the magnetic beads in applications.

Determination of some phthalate acid esters in artificial saliva by gas chromatography–mass spectrometry after activated carbon enrichment

The determination of six phthalate acid esters was achieved in artificial saliva using gas chromatography-mass spectrometry following activated carbon enrichment of samples. Central composite experimental design was applied to optimize method parameters, such as pH, adsorption time and amount of activated carbon. The best compromise of analytical conditions for the simultaneous determination of analytes from spiked artificial saliva were found to be: pH (3), adsorption time (30 min), activated carbon amount (1.8 g L(-1)) and elution solvent (chloroform). These conditions were applied to study the migration of phthalate acid esters from different childrens toys into saliva. A horizontal agitation method was applied to extract the analytes from plastic toys into saliva for 2h at 37°C. The detection limits of the method were in the range of 1.3-5.1 μg L(-1), while the relative standard deviation (%) values for the analysis of 100 μg L(-1) of the analytes were below 3.0% (n=5). Di-2-ethylhexyl phthalate was the main analyte found in these samples.

DETERMINATION OF CADMIUM, CHROMIUM, LEAD, AND MERCURY IN POLYETHYLENE AND POLYPROPYLENE AFTER XYLENE TREATMENT BY ENERGY DISPERSIVE X-RAY FLUORESCENCE SPECTROMETRY

A convenient organic solvent treatment method was developed for the determination of Cd, Cr, Hg, and Pb in polyethylene and polypropylene matrices by energy dispersive X-ray fluorescence spectrometry. The solvent treatment method had many advantages for the fast, simple, and accurate multi-element analysis of these materials. Calibration curves were prepared using organometallic compounds in xylene in the concentration range of 1–80 mg kg−1. The prepared samples had a homogeneous elemental distribution and good durability. The trueness for the quantification of mentioned elements were checked by using a polyethylene certified reference material. The apparent recoveries of the elements with certified values were in the range of 0.81 (Hg) to 1.14 (Pb). The precision was normally better than 8% RSD, with the exception of Hg (10%). The method detection limits were found to be 12, 24, 12, and 12 mg kg−1 for Cd, Cr, Hg, and Pb, respectively. Polyethylene and polypropylene samples were analyzed by both the XRF method and the reference technique for comparative purposes. Application of analysis of variance (ANOVA) showed no differences between the mean results. The proposed method could be also applied to several different xylene soluble plastics.

Assesment of dimethyl phthalate removal from aqueous phase using barium hexaferrite containing magnetic beads.

The barium hexaferrite (BaFe(12)O(19)) containing magnetic poly (ethylene glycol dimethacrylate-vinyl pyridine; mag-poly [EGDMA-VP]) beads (average diameter=53-212 μm) were synthesized and characterized. Their use as an adsorbent in the removal of dimethyl phthalate (DMP) from an aqueous solution was investigated. The mag-poly (EGDMA-VP) beads were prepared by copolymerizing of 4-vinyl pyridine (VP) with ethylene glycol dimethacrylate (EGDMA). The mag-poly (EGDMA-VP) beads were characterized by N(2) adsorption/desorption isotherms (BET), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), elemental analysis, scanning electron microscope (SEM), and swelling studies. At a fixed solid/solution ratio, the various factors affecting the adsorption of DMP from aqueous solutions such as pH, initial concentration, contact time, and temperature were analyzed. The maximum DMP adsorption capacity of the mag-poly (EGDMA-VP) beads was determined as 96.2 mg/g at pH 3.0, 25 °C. All the isotherm data can be fitted with both the Langmuir and the Dubinin-Radushkevich isotherm models. The pseudo-first-order, pseudo-second-order, Ritch-second-order, and intraparticle diffusion models were used to describe the adsorption kinetics. The thermodynamic parameters obtained indicated the exothermic nature of the adsorption. The DMP adsorption capacity did not change after 10 batch successive reactions, demonstrating the usefulness of the magnetic beads in applications.

Diethyl phthalate removal from aqueous phase using poly(EGDMA-MATrp) beads: kinetic, isothermal and thermodynamic studies

In this study, poly(ethylene glycol dimethacrylate-N-methacryloyl-l-tryptophan methyl ester) [poly(EGDMA-MATrp)] beads (average diameter = 106–300 µm), which were synthesized by co-polymerizing of N-methacryloyl-l-tryptophan methyl ester (MATrp) with ethylene glycol dimethacrylate (EGDMA), were used for diethyl phthalate (DEP) adsorption. The various factors affecting the adsorption of DEP from aqueous solutions such as pH, initial concentration, contact time and temperature were analysed. Adsorption behaviour of DEP on the poly(EGDMA-MATrp) beads was investigated by varying pH values of solution, contact time, initial concentration and temperature. An optimum adsorption capacity of 590.7 mg/g for DEP was obtained at 25 °C. The present adsorption process obeyed a pseudo-second-order kinetic model. All the isotherm data can be fitted with the Langmuir, Freundlich and Dubinin–Radushkevich isotherm models. Thermodynamic parameters ΔH = 7.745 kJ/mol, ΔS = 81.92 J/K/mol and ΔG = −16.69 kJ/mol to −18.31 kJ/mol with the rise in temperature from 25 °C to 45 °C indicated that the adsorption process was endothermic and spontaneous.

Dummy molecularly imprinted microbeads as solid-phase extraction material for selective determination of phthalate esters in water

The aim of this study was to investigate the usability of newly synthesized dummy molecularly imprinted microbeads (DMIMs) as a solid phase extraction (SPE) material to determine six phthalate esters (PEs) in water by GC-MS analysis. Diethyl phthalate (DEP) was used as a dummy template to prepare poly(ethylene glycol dimethacrylate N-methacryloyl-l-tryptophan methyl ester) [PEMATrp)] DMIMs by using suspension polymerization. The PEMATrp DMIMs were characterized by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Firstly, the adsorption capacities of the DMIMs prepared in different template molecule (DEP) to functional monomer (MATrp) ratios were investigated by using DEP solutions in the concentration range of 1-500mg/L at pH 3.0. Styrene and vanillic acid were used to evaluate the selectivity of the prepared DMIMs towards the template molecule (DEP). Then, the best analytical conditions were investigated for the simultaneous determination of dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) in aqueous media by using the PEMATrp DMIMs as SPE material. Validation experiments showed that the PEMATrp DMIMs-SPE method had good linearity at 12.5-250.0μg/L (0.988-0.999), good precision (1.2-5.9%), and limits of detection in a range of 0.31-0.41μg/L.

Lead Fractionation Analysis in Lipstick Samples by Inductively Coupled Plasma-Mass Spectrometry

A new analytical approach based on fractionation was introduced for lead in lipstick samples. Different separation techniques including n-hexane, glycerol extraction, and activated carbon adsorption were used to characterize the lipid fraction, polar and aromatic components of the samples. Additionally, artificial saliva and food stimulant extractions were used for the risk assessment studies. Trace metal levels in fractions were determined by inductively coupled plasma-mass spectrometry. Method validation parameters in the total element determinations were defined in terms of detection limits, accuracy, and precision. The limits of detection and quantification were 0.02 and 0.07 mg kg−1 for Pb; whereas the repeatability and reproducibility of the results based on percent relative standard deviation were 3.0% and 7.2% for lead, respectively.