Solid-phase Extraction Adsorbent For Preconcentration Research Articles

Magnetic graphene oxide functionalized dimercaptosuccinic acid/putrescine as a selective and stable solid-phase extraction adsorbent for preconcentration and speciation of arsenic (III) in water samples

ABSTRACT It is challenging for environmental scientists to identify the trace value of arsenite (As(III)) as an essential hazardous material in the presence of arsenate (As(V)) and other metal ions. This paper proposes a method of magnetic solid-phase extraction (MSPE) for the trace analysis of As(III) using magnetite graphene oxide (MGO) covalently functionalised with dimercaptosuccinic acid (DMSA) and putrescine (PUT). The hydrothermally synthesised MGO/DMSA-PUT adsorbent was carefully characterised by using energy-dispersive X-ray spectroscopy analysis, Fourier transform infrared, dynamic light scattering, scanning electron microscopy, zeta potential analyser, X-ray diffraction, and vibrating sample magnetometer techniques in detail. Maximum adsorption capacity of MGO/DMSA-PUT for As(III) was determined 144 mg g−1 which considerably improved vs. graphene oxide with the adsorption capacity of 54.8 mg g−1. Sample pH of 6 with a volume of 50 mL, contact time of 5 minutes, initial concentration of 50 μg L−1, adsorbent dosage of 0.1 g and volume of eluent 3 mL were obtained as the optimised parameters for the developed MSPE procedure. According to experimental data obtained with hydride generation atomic absorption spectroscopy, the linear range and detection limit of the proposed method for As(III) measurement was found to be 0.4–5000 µg L−1 and 9.914 ng L−1, respectively. According to experimental results, a preconcentration limit (PL) of 1.72 µg L−1 was achieved for As(III), corresponding to a preconcentration factor of 965. Statistical analysis of standard reference materials confirmed the accuracy of the method against systematic and constant errors (>95% recovery with <5% RSD). Because of the selectivity of MGO/DMSA-PUT towards the As(III), the developed MSPE procedure is capable for successful speciation and determination of As(III) in water samples with satisfactory analytical results.

Cyclodextrin-derivatized hybrid nanocomposites as novel magnetic solid-phase extraction adsorbent for preconcentration of trace fluoroquinolones from water samples coupled with HPLC-MS/MS determination

A novel cyclodextrin-derivatized hybrid magnetic nanocomposite, denoted as Fe3O4@SiO2@CD, was fabricated and employed as the adsorbent of magnetic solid-phase extraction (MSPE) for preconcentration of elven fluoroquinolones (FQs) from water samples. The prepared nanoparticles exhibited excellent magnetic responsiveness (56.7 emu g−1), uniform size distribution (about 300 nm), good thermal and chemical stability, excellent reusability and superior chemical affinities to the target FQs via hydrogen bond, host–guest inclusion complexation and π–π interactions. Under the optimized conditions, the MSPE was coupled with HPLC-MS/MS to sensitively quantify trance levels of FQs in environmental water. The developed method revealed satisfactory precision with RSDs lower than 4%, good linearity (R2 ≥ 0.9981), low limits of detection (0.0014–0.023 µg L−1) and satisfactory recoveries (93.2–105%). Furthermore, the proposed approach was validated by analyzing the Certified Reference Material of GBW 10152 and GBW 10153 chicken meat powder. These results demonstrated that the Fe3O4@SiO2@CD nanoparticles are a promising magnetic adsorbent for FQs, and the established MSPE-HPLC-MS/MS approach is suitable for simultaneous analysis of trace levels of FQs in actual samples.

Coconut Shell Activated Carbon as Solid-Phase Extraction Adsorbent for Preconcentration of Selected Pesticides from Water Samples

Solid-phase extraction (SPE) on activated carbon derived from coconut shell (CSAC) for the preconcentration of four varying polarity pesticides (imidacloprid, acetamiprid, simazine, and linuron) prior to their determination using high performance liquid chromatography with diode array detector (HPLC-DAD) was investigated. The characteristics of the CSAC were analyzed through X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) method. The effects of the solution pH, eluent type, eluent volume, and flow rate were investigated for optimization of the presented procedure. The adsorption was achieved quantitatively on the CSAC column in the pH range of 2.0–7.0, and then the retained pesticides were eluted with dichloromethane. The detection limit was found to be 0.025–0.039 μg L−1, depending on the pesticide. The proposed SPE-CSAC method was used to determine selected pesticides in tap water samples. The recoveries ranged from 58.2 to 105.3%, with low relative standard deviations. The obtained results indicated that the CSAC could be efficiently used as a low cost alternative to commercially available SPE adsorbents for the determination of the varying polarity pesticides in environmental water samples at trace levels.

Preparation and evaluation of a porous molecularly imprinted polymer for selective recognition of the antiepileptic drug carbamazepine

A novel and porous molecularly imprinted polymer (PMIP) was synthesized and used as a solid-phase extraction adsorbent for preconcentration of carbamazepine (CBZ) prior to its quantitation by high-performance liquid chromatography (HPLC) in various sample forms (e.g., drinking water, river water, hospital wastewater, and pharmaceuticals). PMIP-CBZ was applied to a polymerization process in which polystyrene spheres were coated with a silica layer. Removal of polystyrene spheres and formation of porous silica facilitated the recovery of CBZ (99.4%) during the extraction process. Site accessibility to the surface of PMIP-CBZ increased the density of high-recognition sites. PMIP-CBZ was characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy. The key variables influencing the extraction efficiency of PMIP (e.g., adsorbent loading, eluent type, eluent volume, reusability of the adsorbent, and cross-reactivity) were optimized. The optimized protocol was successfully employed to quantify CBZ with limit of detection and limit of quantification as 0.082 and 0.270 ng/mL, respectively (linear detection range: 0.5–250 ng/mL and a relative standard deviation: < 5%). Use of the PMIP adsorbent resulted in a sensitive and stable method for efficiently quantitation of CBZ from various real sample matrices.