Complex formation and enantioselectivity studies of triazole fungicide and organophosphorus pesticide enantiomers using capillary electrophoresis

Several cyclodextrin modified-micellar electrokinetic chromatography (CDMEKC) methods were developed for the successful triazole fungicides separation. In the first part, an efficient method was developed for the simultaneous enantioseparation of cyproconazole (4 stereoisomer), bromuconazole (4 stereoisomer) and diniconazole (2 stereisomer) enantiomers using CD-MEKC with a dual mixture of neutral cyclodextrins as chiral selector. The best simultaneous separation of cyproconazole, bromuconazole, and diniconazole enantiomers was achieved with a mixture of 27 mM HP-β-CD and 3 mM HP-γ-CD in 25 mM phosphate buffer (pH 3.0) containing 40 mM sodium dodecyl sulfate (SDS) and 15% iso-propanol as organic modifier. Complete separation of 10 stereoisomer of triazole fungicides were obtained in a single run with good resolution (Rs 1.74“26.31) and high peak efficiency (N > 400 000). In the second part of the study, enantioseparation of hexaconazole, penconazole, myclobutanil, and triadimefon was investigated. Simultaneous enantioseparation of penconazole, myclobutanil, and triadimefon was achieved under acidic condition (pH 3.0) using 25 mM phosphate buffer, 50 mM SDS, and 30 mM HP-γ-CD, with Rs greater than 0.9 whereas, simultaneous enantioseparation of hexaconazole, penconazole, and myclobutanil was successfully achieved under neutral condition (pH 7.0) using 25 mM phosphate buffer, 40 mM SDS, and 40 mM HP-γ-CD, with Rs greater than1.6. In order to improve detection sensitivity, on-line preconcentration technique was investigated. It was found that sweeping technique as an on-line preconcentration technique improved the detection sensitivity of the enantioseparation of cyproconazole, bromuconazole, and diniconazole by 30 to 60-fold, with good repeatabilities in the migration time, peak area and peak height were obtained with RSDs in the range of 0.08“0.32%, 0.03“ 2.44%, and 2.13“8.44% respectively. Furthermore, sweeping technique improved the detection sensitivity of the enantioseparation of hexaconazole, penconazole and myclobutanil by 62- to 67-fold. Good repeatabilities in the migration time, peak area and peak height were obtained with RSDs in the range of 2.39“3.90%, 1.96€“6.15%, and 2.80“6.64% respectively. Finally, the formation constant of diniconazole enantiomers with HP-γ-CD under neutral and acidic condition was investigated using CD-MEKC

Effects of kappa carrageenan and glycerol in purple sweet potato starch based edible film

The solubility and mechanical properties of purple sweet potato (PSP) starch - based edible films are being investigated. The formulation was prepared using a constant amount of PSP starch (4 % w/v) with five different ratios of carrageenan and glycerol (1:1 , 1.5:0.5, 0.5:1.5, 0.5:0.5, 1:0) which act as gelling agent s and plasticizers respectively. PSP starch generates 61.79 mg/100 g anthocyanin and retains 16.78 % antioxidant capacity . Carrageenan and glycerol (0.5:1.5) ratio shows the highest solubility in water ( 53.50 ± 0.1085 % ) and highest tensile strength (9.1674 ± 0.5399 MPa) with the lowest elongation at break (20.436 ± 2.826 %)

Optimization of sol-gel hybrid mediated hollow fiber-solid phase microextraction for the analysis of selected aldehydes

Hexanal and heptanal are two promising aldehydes that have been found in biological samples of lung cancer patients. In general, aldehydes can be detected in trace level as low as part per billion or part per trillion levels. Since reliable technique is needed to detect the analyte of interest especially in complex matrices, a new hybrid silica-based material as the adsorbent of hollow fiber-solid phase microextraction (HF-SPME) was synthesized. In the present work, the solgel hybrid material was held in the pores of HF by in situ gelation and was used to extract the two test aldehydes using direct immersion sampling mode. Several solgel parameters affecting the extraction performance of the in-house sol-gel hybrid material were optimized. The extraction efficiencies of the new silica-based hybrid material for the target aldehydes were based on peak area response obtained from gas chromatography-flame ionization detector. The best extraction efficiencies of hexanal and heptanal were obtained using a mol ratio of 1:4 for the two precursors used, 6 mmol water, 6 mmol methanol and 2.5 mmol trifluoroacetic acid for in situ gelation HF-SPME. The new in situ sol-gel silicabased adsorbent material exhibits high potential for HF-SPME of hexanal and heptanal

Gelatin-alginate coated cellulose acetate membrane for the extraction of heavy metal ions from water samples

Heavy metal ions are a common water pollutant from industrialized areas and extraction is one of the most popular methods to remove the target analytes. However, extraction and determination of metal ions in water are often very difficult to perform due to their solubility in water. In order to resolve some of the issues in the extraction of trace metal ions from aqueous samples, this study explores newly prepared polyelectrolyte films coated on cellulose acetate membrane as extracting phase. Optimization coating materials showed that gelatin-alginate coated cellulose acetate membrane have the best performance to adsorb metal ions from water. The results open a possibility of the method to be successfully applied as extracting phase to adsorb and enrich heavy metal ions from aqueous matrices

New application of magnetic nanoparticles for adsorption of nickel(II) metal ions from aqueous solution by batch method

Ni(II) is toxic for living organism at trace levels. Currently the Environmental Protection Agency (EPA) standard for Ni(II) in drinking water is 0.04 mg/L [1]. The adsorption of metal ions using magnetic nanoparticles is preferred due to their lower costs, have high adsorption capacities, durability and high efficiency, especially for metal ions with trace and ultra-trace concentration level [2]. In this study, an in-house synthesized Fe3O4 MNPs adsorbent was evaluated for its feasibility in the adsorption of Ni(II) metal ions from aqueous solutions. Adsorption experiments were investigated by kinetic and isotherm adsorption models

New dispersive solid phase miroextraction sorbent based on so-gel bybrid material for non-sterioidal anti- inflammatory drug analyis in water

Dispersive solid phase microextraction (DSPME) is a simple and environmental friendly sample preparation technique. In DSPME, the sorbent is used for trapping the analyte/s out of the solution and then the analyte/s is to a smaller volume of a second desorption solvent. In this study, a new DSPME sorbent material based on a hybrid organic–inorganic methyltrimethoxysilane–cyanopropyltriethoxysilane (MTMOS–CNPrTEOS) was synthesized by using two steps sol–gel method. The new DSPME hybrid sorbent was used in determination of three selected NSAIDs namely, diclofenac sodium, ketoprofen and mefenamic acid in water samples prior to high performance liquid chromatography with ultraviolet (HPLC-UV) detection. Under the optimized conditions, the method demonstrated good linearity (0.2–500 µg L-1) with excellent coefficient of determination (r2 > 0.9991), good RSDs (<2.4%, n = 3), good limit of detection (0.03–0.12 µg L-1) and excellent recoveries (93.5–97.6%). The DSPME method using the new sol-gel hybrid MTMOS–CNPrTEOS material combined with HPLC–UV proved to be a simple, cost efficient and requires minimial amount of organic solvent that support green chemistry concepts

Magnetic micro-solid-phase extraction based on magnetite-MCM-41 with gas chromatography–mass spectrometry for the determination of antidepressant drugs in biological fluids

A new facile magnetic micro‐solid‐phase extraction coupled to gas chromatography and mass spectrometry detection was developed for the extraction and determination of selected antidepressant drugs in biological fluids using magnetite‐MCM‐41 as adsorbent. The synthesized sorbent was characterized by several spectroscopic techniques. The maximum extraction efficiency for extraction of 500 μg/L antidepressant drugs from aqueous solution was obtained with 15 mg of magnetite‐MCM‐41 at pH 12. The analyte was desorbed using 100 μL of acetonitrile prior to gas chromatography determination. This method was rapid in which the adsorption procedure was completed in 60 s. Under the optimized conditions using 15 mL of antidepressant drugs sample, the calibration curve showed good linearity in the range of 0.05–500 μg/L (r2 = 0.996–0.999). Good limits of detection (0.008–0.010 μg/L) were obtained for the analytes with good relative standard deviations of <8.0% (n = 5) for the determination of 0.1, 5.0, and 500.0 μg/L of antidepressant drugs. This method was successfully applied to the determination of amitriptyline and chlorpromazine in plasma and urine samples. The recoveries of spiked plasma and urine samples were in the range of 86.1–115.4%. Results indicate that magnetite micro‐solid‐phase extraction with gas chromatography and mass spectrometry is a convenient, fast, and economical method for the extraction and determination of amitriptyline and chlorpromazine in biological samples

New sol-gel silica nanoparticles coated cyanopropyltriethoxysilane as alternative solid phase extraction sorbent for organophosphorus pesticides

Sorbents based on silica are widely used in solid phase extraction (SPE). The most common SPE material is C18.Recently nanoparticleshave gained interest as sorbent materials for analytical purpose. In this study silica-based nanoparticles with polar and non-polar groups were synthesized using cyanopropyltriethoxysilane (CNPrTEOS) and tetraethoxysilane (TEOS) as precursor in the presence of ammonia solution as catalyst and ethanol as solvent via sol-gel technology. The sol-gel SiO2-NPs-CNPrTEOS was used for the simultaneous extraction of three organophosphorus pesticides (OPPs) of different polarity namely dicrotophos, diazinon and chlorpyrifos prior to LC-UV detection at 270 nm. The sorbent produced was characterized using FTIR, FESEM, nitrogen gas adsorption and TGA. The surface area and average pore diameter of the sorbent are 570 m2 g-1 and 31Å (mesoporous), respectively. The average particle size of SiO2-NPs-CNPrTEOS is 54 nm. The mesoporous SiO2-NPs-CNPrTEOS showed superior extraction capability for the polar dicrotophos and also for the non-polar diazinon and chlorpyrifos compared to commercial cyano SPE. The new SiO2-NPs-CNPrTEOS exhibits high potential as a bipolar sorbent for the simultaneous extraction of polar and non-polar OPPs. Keywords Sol-gel, Solid phase extraction, Nanoparticles sorbent, Cyanopropyltriethoxysilane, Tetraethoxysilane, Organophosphorus pesticides, Liquid chromatography-UV detection

Microextraction of Xenobiotics and Biomolecules from Different Matrices on Nano Structures

Sample preparation is the backbone of any analytical procedure; it involves extraction and pre-concentration of the desired analytes; often at trace levels. The present article describes the applications of nanomaterials (carbon based inorganic and polymeric materials) in miniaturized extraction such as solid phase micro-extraction, stir-bar sorptive extraction, liquid phase micro-extraction, and dispersive liquid phase micro-extraction in the analyses of aqueous samples. The nanoparticles used for micro-extractions are discussed on the basis of their chemical natures. The synthetic route and the preparation of nanomaterials are described along with the optimization strategies for micro-extraction. A comparison between the conventional materials and nanomaterials for micro-extraction is proposed. The key roles of the nanomaterials for the micro-extraction of different analytes such as drugs, pesticides, polycyclic aromatic hydrocarbons, proteins and peptides from aqueous samples are reported. The use of nanomaterials, combined with miniaturized micro-extraction techniques, proved to be highly promising for sample preparation of various matrices with analytes at trace levels

High temperature liquid chromatography of triazole fungicides on polybutadiene-coated zirconia stationary phase

High temperature liquid chromatography using water-rich and superheated water eluent is evaluated as a new approach for the separation of selected triazole fungicides, hexaconazole, tebuconazole, propiconazole, and difenoconazole. Using a polybutadiene-coated zirconia column at temperatures of 100–150 oC, clear separations were achieved when 100% purified water was utilized as organic-free eluent. Excellent limits of detection down to pg level were obtained for the separation of the triazole fungicides under optimum conditions. Van’t Hoff plots for the separations were linear suggesting that no changes occurred in the retention mechanism over the temperature range studied