Synthesis and characterisation of rice husk ash silica drug carrier for α-mangostin

The potential of rice husk ash (RHA) silica prepared via sol-gel method (RHA-Si) as a drug carrier was investigated. The nitrogen adsorption-desorption isotherm of RHA-Si indicates the presence of mesopores and some small percentage of micropores. The Brunauer, Emmett and Teller (BET) surface area of RHA-Si was 589 m2 g–1 and the Barrett-Joyner-Halenda (BJH) pore size was 5.1 nm. The adsorption of α-mangostin was confirmed by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The sample containing α-mangostin was labeled as RHA-Si-α. The BET surface area of RHA-Si-α was 110 m2 g–1 with the BJH pore size of 24.4 nm. The X-ray powder diffraction (XRD) showed that the RHA-Si and RHA-Si-α were amorphous. The disappearance of crystallinity of α-mangostin indicates that the solubility and dissolution of α-mangostin have been improved. The drug release profile indicated a burst release corresponding to 47% of the total drug loading in the first 15 min. The burst release was caused by physically adsorbed drug molecules. The findings suggest that RHA silica has potential application as nano drug carrier

S-quinolin-2-yl-methyldithiocarbazate-based magnetic adsorbent for magnetic solid-phase extraction of heavy metals from water samples

New S-quinolin-2-yl-methyl-dithiocarbazate-based magnetic adsorbent (MNP-SQ2MDTC) for magnetic solid phase extraction (MSPE) was developed for the determination of Cd2+ and Cu2+ in water samples. The surface of MNP was first coated with (3-aminopropyl) triethoxysilane (APTES) as cross-linker and then SQ2MDTC incorporated covalently to the coated MNP. The newly prepared MNPSQ2MDTC was analysed by Fourier Transform infrared (FT-IR), X-ray diffractometer (XRD), energy dispersive X-ray spectroscopy (EDX), vibrating-sample magnetometry (VSM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). Under optimal MSPE conditions (20 mg adsorbent dispersed in 25 mL of sample which adjusted to pH 6.0 and sonicated for 10 min, before desorbed in 0.5 mL of 1 M HClO4 and sonicated for 5 min), the validation method revealed a good linearity (0.1–5.0 μg mL−1) with the coefficient of determination (R2) in the range of 0.995–0.996 for the samples. The limits of detection (LOD) of the developed method for Cd2+ and Cu2+ were found to be 0.054 and 0.040 μg mL−1, and limit of quantification (LOQ) were 0.180 and 0.134 μg mL−1, respectively. The recoveries of Cd2+ ranged from 75.6% to 93.9% and from 81.5% to 98.7% for Cu2+. To the best of our knowledge, this is the first study that have investigated the use of magnetic nanoparticles coated SQ2MDTC for determination of Cd2+ and Cu2+ in water samples analysis based on complexation of the metal ions to the surface of amino groups

Application of a new choline-imidazole based deep eutectic solvents in hybrid magnetic molecularly imprinted polymer for efficient and selective removal of naproxen from aqueous samples

A magnetic molecularly imprinted polymer (Fe3O4@MIP) with naproxen (as template) was successfully prepared by adding a co-solvent consisting of a choline-imidazole based deep eutectic solvent (ChCl-BuIM) during polymerisation. The morphological, functional group, and magnetic characteristics of the synthesised materials were characterised by elemental analysis, Fourier transform-infrared spectroscopy, scanning electron microscopy, and vibrating sample magnetometer. This hybrid Fe3O4@MIP-ChCl-BuIM material was used as a magnetic adsorbent for efficient and selective removal of naproxen from wastewater samples. A batch adsorption study showed that adsorption of naproxen onto the multilayer surface of the adsorbent through a chemisorption mechanism. The data showed that the adsorption was feasible, spontaneous, and exothermic. The Fe3O4@MIP-ChCl-BuIM removed more naproxen (93.2–97.1%) than Fe3O4@MIP without ChCl-BuIM (83.2–88.9%). This finding confirms that the use of ChCl-BuIM improved both the selectivity and affinity of the MIP adsorbent towards naproxen. Competitive recognition studies of the Fe3O4@MIP-ChCl-BuIM using naproxen and structurally similar non-steroidal anti-inflammatory drugs revealed that the Fe3O4@MIP-ChCl-BuIM had high selectivity for naproxen. A cytotoxicity test showed that the synthesised ChCl-BuIM was non-toxic, as the human normal cell lines MCF-10A, and BEAS-2B maintained viability above 50%. These results show that Fe3O4@MIP-ChCl-BuIM has potential for use as a functional adsorption material for the removal of naproxen from water samples

Ultrasound-assisted surfactant enhanced emulsification microextraction method coupled with gas chromatography-mass spectrometry for the determination of selected polycyclic aromatic hydrocarbons in aqueous samples

A simple and rapid microextraction method termed as ultrasound-assisted surfactant enhanced emulsification microextraction (UASEME) was developed for the determination of fluoranthene (FLU) and phenanthrene (PHE) in aqueous samples followed by gas chromatography-mass spectrometry (GC-MS). Six important parameters, that affect the extraction efficiency of polycyclic aromatic hydrocarbons (PAHs) were evaluated and the results were as follows; extraction solvent (toluene), volume of extraction solvent (30 μL), surfactant (Tween 20), volume of surfactant (15 μL), extraction time (2 minutes) and with no salt addition. Under the optimum conditions, the method showed good linearity over the concentration range from 1 – 1000 μg L- 1 with correlation coefficients (R² ≥ 0.9932), acceptable limits of detection (0.3 μg L- 1) and limits of quantification (1.0 μg L- 1) for both analytes. Good relative recovery values, in the range of 91.75 – 104.1%, were obtained for tap water samples. The relative standard deviations (RSDs) were 1.62 – 10.32% (n = 3). The proposed method was applied for the determination of FLU and PHE in tap water and sugarcane juices

Molecularly imprinted silica gel incorporated with agarose polymer matrix as mixed matrix membrane for separation and preconcentration of sulfonamide antibiotics in water samples

Molecularly imprinted silica gel (MISG) was incorporated through dispersion in agarose polymer matrix to form a mixed matrix membrane (MMM) and was applied for the determination of three sulfonamide antibiotic compounds (i.e. sulfamethoxazole (SMX), sulfamonomethoxine (SMM), and sulfadiazine (SDZ)) from environmental water samples. Several important microextraction conditions, such as type of desorption solvent, extraction time, amount of sorbent, sample volume, pH, and effect of desorption time, were comprehensively optimized. A preconcentration factors of ≥ 20 was achieved by the extraction of 12.5 mL of water samples using the developed method. This microextraction-HPLC method demonstrated good linearity (1–500 μg L–1) with a coefficient of determination (R2) of 0.9959–0.9999, low limits of detection (0.06–0.17 μg L–1) and limits of quantification (0.20–0.56 μg L–1), good analyte recoveries (80–96%), and acceptable relative standard deviations (< 10%) under the optimized conditions. The method is systematically compared to those reported in the literature

Three-phase liquid-phase microextraction for the determination of partition coefficient and analysis of nitrophenols

Liquid-phase microextraction (LPME) has become a very popular technique because it is inexpensive, easy to operate and solvent-free. As the distinct advantages of LPME were proven, it is therefore of interest to investigate the three-phase liquid-phase LPME and the partition coefficient of selected nitrophenols. In this study, a three-phase hollow fiber liquid-phase microextraction (HF-LPME) method coupled with capillary electrophoresis (CE) has been developed. The selected nitrophenols were extracted from 14 mL aqueous solution (donor solution) with the pH adjusted to pH 3 into an organic phase (1-octanol) immobilized in the pores of the hollow fiber and finally back-extracted into 40.0 µL of the acceptor phase (NaOH) at pH 12.0 located inside the lumen of the hollow fiber. The extractions were carried out under optimum conditions (donor solution: 0.05 M H3PO4, pH 3.0; organic solvent: 1-octanol; acceptor solution: 40 µL of 0.1 M NaOH, pH 12.0; agitation rate: 1050 rpm; extraction time: 15 min). Under optimized conditions, the limit of detection (LOD) obtained were between of 0.01 – 0.04 ppm. Excellent enrichment factors of up to 398-folds were obtained. The determination of partition coefficients of analytes in three-phase HF-LPME was successfully achieved. It was found that the partition coefficient (Ka/d) values were high for 2-nitrophenol, 3-nitrophenol, 4-nitrophenols, 2,4- dinitrophenol and 2,6-dinitrophenol and the individual partition coefficients (Korg/d and Ka/org) promoted efficient simultaneous extraction from the donor through the organic phase and further into the acceptor phase. The developed method was successfully applied for the determination of nitrophenols in water samples

Application of newly synthesized titanium (iv) butoxide-cyanopropyltriethoxysilane sorbent for the extraction of aromatic amines in water samples / Mazidatulakmam binti Miskam

A new titanium (IV) butoxide-cyanopropyltriethoxysilane (Ti-CNPrTEOS) hybrid material was successfully synthesized as sorbent for the extraction of polar aromatic amines. The sorbent was synthesized by hydrolysis and condensation of titanium (IV) butoxide and cyanopropyltriethoxysilane with the presence of hydrochloric acid as catalyst via sol-gel method. Under the optimum synthesis conditions (tetrahydrofuran as solvent, 1.2 M of hydrochloric acid catalyst, 4 mol of water content with ratio of titanium (IV) butoxide and cyanopropylteriethoxysilane of 1:1 and aging temperature of 60°C), the sorbents were characterized by Fourier Transform-Infrared, Field-Emission Scanning Electron Microscopy-Energy, CHN elemental analysis, Brunauer–Emmett–Teller (BET) desorption and thermogravimetric analysis. A solid phase extraction (SPE) method has been developed using Ti-CNPrTEOS sorbent for the determination of aromatic amines and optimum experimental conditions were sample at pH 7, dichloromethane as conditioning solvent, 10 mL sample loading volume, 5 mL of acetonitrile as the eluting solvent. The limit of detection (LOD) and limit of quantification (LOQ) using Ti-CNPrTEOS SPE sorbent (0.01-0.20; 0.03-0.61 µgL-1) were absolutely lower compared with those achieved using silica-cyanopropyl (Si-CN) SPE sorbent (0.23-1.47; 0.75-4.91 µgL-1) and C18 SPE sorbent (0.36-0.98; 1.54-2.56 µgL-1). The recoveries and repeatability obtained from water samples using the sol–gel Ti-CNPrTEOS SPE sorbent were 57–99% and RSDs 1–4%, n=5. The lowest recovery of non-polar diethylaniline, DEA (57%) indicated that the sorbent was very selective towards the extraction of polar aromatic amines. Ti-CNPrTEOS sorbent was also successfully applied as sorbent for solid phase membrane tip extraction (SPMTE). Under the optimum extraction conditions; 15 mL of sample at pH 7, acetonitrile as conditioning and desorption organic solvent, extraction time of 15 min and desorption time of 15 min, the method showed good linearity with acceptable reproducibility (RSD 2.5 – 3.6%, n = 5) and LOD and LOQ for Ti-CNPrTEOS SPMTE (0.13 – 6.23 ngL-1; 0.53 – 5.67 ngL-1) were lower with those achieved by C18-SPE (0.36-0.98 gL-1; 1.54-2.56 gL-1). The application of the Ti-CNPrTEOS SPMTE sorbent was successfully carried out by analysis of aromatic amines in river water sample with the recovery between 49–99%. The lowest recovery of non-polar DEA (49%) indicated that the sorbent was very selective towards the extraction of polar aromatic amines. The newly developed method using Ti-CNPrTEOS sorbent was proven as a simple, rapid, cheap and solvent efficient extraction technique

Preparation and characterization of titania-cyanopropyltriethoxysilane sorbent for the extraction of polar aromatic amines

A new titanium(IV) butoxide-cyanopropyltriethoxysilane (Ti-CNPrTEOS) hybrid material was successfully synthesized for the use as sorbent for the extraction of polar aromatic amines. The sorbent was synthesized by hydrolysis and condensation of titanium(IV) butoxide and cyanopropyltriethoxysilane with the presence of hydrochloric acid as catalyst via sol–gel method. Several factors influencing the synthesized sorbent such as solvent selection, mol of water content, ratio of titanium(IV) butoxide and cyanopropyltriethoxysilane and aging temperature were investigated and optimized. The sorbents were characterized by fourier transform-infrared, field-emission scanning electron microscopy-energy, CHN elemental analysis and thermogravimetric analysis. The applicability of the sorbents for the extraction of polar aromatic amines by the batch sorption method was extensively studied and evaluated. Under the optimum synthesis conditions (tetrahydrofuran as solvent, 1.2 M of hydrochloric acid catalyst, 4 mol of water content with ratio of titanium(IV) butoxide and cyanopropylteriethoxysilane of 1:1 and aging temperature of 60 C), the extraction showed high recovery towards the extraction of polar aromatic amines. The synthesized sorbent was successfully applied for the extraction of selected aromatic amines via batch sorption method in waste water samples prior to the gas chromatography-flame ionization detector separation. The synthesized sol–gel Ti-CNPrTEOS sorbent demonstrated the potential as an alternative extraction sorbent with higher selectivity towards polar aromatic amines

Determination of polar aromatic amines using newly synthesized sol–gel titanium (IV) butoxide cyanopropyltriethoxysilane

A solid phase extraction (SPE) method has been developed using a newly synthesized titanium (IV) butoxide-cyanopropyltriethoxysilane (Ti-CNPrTEOS) sorbent for polar selective extraction of aromatic amines in river water sample. The effect of different parameters on the extraction recovery was studied using the SPE method. The applicability of the sorbents for the extraction of polar aromatic amines by the SPE was extensively studied and evaluated as a function of pH, conditioning solvent, sample loading volume, elution solvent and elution solvent volume. The optimum experimental conditions were sample at pH 7, dichloromethane as conditioning solvent, 10 mL sample loading volume and 5 mL of acetonitrile as the eluting solvent. Under the optimum conditions, the limit of detection (LOD) and limit of quantification (LOQ) for solid phase extraction using Ti-CNPrTEOS SPE sorbent (0.01-0.2; 0.03-0.61 µg L(-1)) were lower compared with those achieved using Si-CN SPE sorbent (0.25-1.50; 1.96-3.59 µg L(-1)) and C18 SPE sorbent (0.37-0.98; 1.87-2.87 µg L(-1)) with higher selectivity towards the extraction of polar aromatic amines. The optimized procedure was successfully applied for the solid phase extraction method of selected aromatic amines in river water, waste water and tap water samples prior to the gas chromatography-flame ionization detector separation

Determination of partition coefficients for nitrophenols using three phase hollow fiber liquid phase microextraction

A hollow fiber supported liquid phase microextraction method for determination of nitrophenols has been developed.In this work, selected phenolic compounds (2-nitrophenols, 3-nitrophenols, 4-nitrophenols, 2,4-dinitrophenols and 2,6-dinitrophenols) were extracted from the aqueous donor solution by three phase liquid phase microextraction (LPME) based on the migration of the analytes through a thin layer of organic solvent immobilized within the pores of the wall of porous hollow fiber into a small (a few μL) volume of acceptor solution inside the lumen of the hollow fiber. After extraction, the acceptor solution was injected to capillary zone electrophoresis (CZE) system for analysis. Different parameters affecting the extraction process such as extraction time, length of hollow fiber and organic solvent have been studied. Partition coefficients of the analytes were found to be directly related to the enrichment factor. High partition coefficients and enrichment factors can be obtained by proper selection of the organic solvent and by pH condition in the aqueous solutions