Graphene Oxide-based Solid Phase Extraction Research Articles

C8-modified magnetic graphene oxide based solid-phase extraction coupled with dispersive liquid-liquid microextraction for detection of trace phthalate acid esters in water samples

Phthalate acid esters (PAEs) are extensively applied in plastic and plastic products, and have caused potential hazards on human and animal health. In this study, a highly sensitive method was proposed for trace detection of selected PAEs in water by gas chromatography-mass spectrometry, after solid-phase extraction (SPE) using octyl (C8)-modified magnetic graphene oxide (MGO-C8) as the adsorbent followed by dispersive liquid-liquid microextraction (DLLME). The prepared MGO-C8 was characterized by Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric analysis (TGA) and vibrating sample magnetometry (VSM). The recoveries of the PAEs using MGO-C8 as the adsorbent were found to be significantly higher those obtained by MGO. The influences of solution pH, adsorption and desorption time, eluent and extractant, and salt addition on the extraction efficiency of PAEs were investigated. Under the optimized conditions, limits of detection (LODs) of 0.5–1.0 ng L−1 for PAEs, and related standard deviations (RSDs) of 4.8–7.5% were obtained. The proposed method was utilized in the detection of trace PAEs in real environmental water samples, with spiked recoveries of 89.5–112.3%, 91.5–105.0% and 98.0–110.0% for DBP, DEHP and DNOP, respectively.

Determination of trace bisphenol A in environmental water by high-performance liquid chromatography using magnetic reduced graphene oxide based solid-phase extraction coupled with dispersive liquid-liquid microextraction.

Bisphenol A (BPA), an endocrine-disrupting chemical, has received much attention from researchers and the general public. In this paper, a novel method of determining BPA at trace levels was developed, using magnetic reduced graphene oxide (rGO-Fe3O4)-based solid-phase extraction coupled with dispersive liquid-liquid microextraction (DLLME), followed by high-performance liquid chromatographic determination. The rGO-Fe3O4 was prepared and then characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometry. The greatest saturation magnetization of rGO-Fe3O4 was up to 43.8emug-1, which allowed rapid isolation of the rGO-Fe3O4 from solutions upon applying an appropriate magnetic field. The effects of solution pH, adsorbent amount, type and volume of eluent and extraction solvent, extraction time, and salt concentration on the extraction efficiency of BPA were examined and optimized. Under the optimum conditions, an enrichment factor of 5217 and an LOD of 0.01μgL-1 for BPA were obtained. The reusability of rGO-Fe3O4 for at least 12 repeated cycles without any significant decrease in the extraction recovery of BPA was demonstrated. The proposed method was applied to the determination of BPA in different real water samples, with relative recoveries of 84.8-104.9% and RSDs of 0.8-8.3% in the spiked concentration range 1-10μgL-1.

Interference free and fast determination of manganese(II), iron(III) and copper(II) ions in different real samples by flame atomic absorption spectroscopy after column graphene oxide-based solid phase extraction

A solid phase extraction (SPE) and flame atomic absorption spectroscopy (FAAS) for the determination of Mn(II), Fe(III) and Cu(II) ions with a graphene oxide (GO) packed column and 1-Phenyl-3-(2-thienylmethyl)thiourea (PTT) as chelating reagent was studied. In theoretical part, the PM6 semi-empirical and PBE density functional theory methods were used for investigation of adsorption mechanism of the complexes on GO sheet. The calculated thermochemistry of the complexation reactions was reported. Based on quantum theory of atoms in molecules (QTAIM) analysis, the nature of the metal/ligand bonding was discussed. Extraction efficiency and the effects of parameters such as flow rate, pH, type and the least amount of acid for stripping of understudied ions from the modified column and break through volume were examined. The preconcentration factor was 280 (for 1400mL of sample solution and flow rate of 10mLmin−1) and detection limit of the proposed method was found in the range of 0.06–0.49μgL−1. The developed method was successfully applied to the determination of Mn(II), Fe(III) and Cu(II) ions in leaves of spinach, honey, hair, blood and various water samples.

Graphene oxide-based solid phase extraction of vitamin B12from pharmaceutical formulations and its determination by X-ray fluorescence

In the present study, a novel quantitative method, namely solid phase extraction, was applied to extract vitamin B12 from pharmaceutical formulations. The technique involves the use of graphene oxide (GO) as an efficient adsorbent for solid-phase extraction of vitamin B12. Collection of GO from aqueous solution was simply achieved by applying filtration assembly. The extracted analyte was directly analyzed by using X-ray fluorescence (XRF) spectroscopy. Factors affecting the extraction efficiency were investigated and optimized. Under the optimum conditions, enhancement factor of 46, linear dynamic range of 25–1000 µg l−1 with correlation of determination (R2 = 0.998) and limit of detection of 20 µg l−1 were obtained for vitamin B12. The percent relative standard deviation based on three-replicate determination was less than 8.1%. The method was successfully applied for extraction and determination of vitamin B12 in different types of pharmaceutical samples such as multivitamin tablet, effervescent tablet and injection sample. The results showed that the proposed method based on GO was a simple, accurate, and highly efficient approach for analysis of vitamin B12. Copyright © 2014 John Wiley & Sons, Ltd.

Flame Atomic Absorption Spectrometric Determination of Pb(II) and Cd(II) in Natural Samples After Column Graphene Oxide-Based Solid Phase Extraction Using 4-Acetamidothiophenol

The determination of lead and cadmium by flame atomic absorption spectrometry after solid phase extraction on graphene oxide column with use of 4-acetamidothiophenol (ATP) as chelating reagent was described. PM6 semi-empirical and PBE density functional theory methods were used to investigation of adsorption mechanism of the complexes on GO sheet. The main factors influencing the preconcentration and determination of the analytes (pH, ATP amount, eluent type and concentration, flow rate and sample volume) were examined in detail. The effect of interfering ions on the separation-preconcentration of analytes was also investigated. For Pb(II) and Cd(II) solutions of 1.0 µg L-1, the preconcentration factor was as high as 250 (under the optimized conditions). The detection limits for Pb(II) and Cd(II) were 170 and 80 ng L-1, respectively. The validity of the proposed method was checked with standard reference materials and it has been successfully applied for the determination of trace Pb(II) and Cd(II) in water, herbal and fish samples with the recoveries of 99.4-103.5%.

Combination of graphene oxide-based solid phase extraction and electro membrane extraction for the preconcentration of chlorophenoxy acid herbicides in environmental samples

Combination of different extraction methods is an interesting and debatable work in the field of sample preparation. In the current study, for the first time, solid phase extraction combined with electro membrane extraction (SPE–EME) was developed for ultra-preconcentration and determination of chlorophenoxy acid herbicides in environmental samples using capillary electrophoresis (CE). In the mentioned method, first, a 100mL of chlorophenoxy acid herbicides (2-methyl-4-chlorophenoxyacetic acid (MCPA), 2-(2,4-dichlorophenoxy) propanoic acid (2,4-DP) and 2-(4-chloro-2-methylphenoxy) propanoic acid (MCPP)) was passed through a column of graphene oxide as a solid phase, and then the adsorbed herbicides were eluted by 4.0mL of 8% acetic acid (HOAC) in methanol. Then, the elution solvent was evaporated and the herbicides residue was dissolved in 4.0mL of double distilled water (pH 9.0). Afterwards, the herbicides in 4.0mL of the aqueous solution were transferred to an EME glass vial. In the EME step, the herbicides were extracted from the sample solution into the basic acceptor solution (pH 13.0) under electrical potential, which was held inside the lumen of the fiber with 1-octanol as the supported liquid membrane (SLM). Under the optimized conditions, high enrichment factors were obtained in the range of 1950–2000. The limits of quantification (LOQs) and method detection limits (MDLs) were obtained in the range of 1.0–1.5 and 0.3–0.5ngmL−1, respectively. Finally, the performance of the present method was evaluated for extraction and determination of chlorophenoxy acid herbicides in environmental samples.