Solid Phase Extraction Studies Research Articles

On-line quantification of solid-phase metal extraction efficiencies using instrumented millifluidics platform

A semi-automated and fully integrated millifluidic platform has been developed for rapid development and study of Solid-phase extraction (SPE) processes. In this instrumented setup, the fluid coming out of the extraction mini-column is analysed directly using on-line X-ray fluorescence, enabling a real-time, fast and accurate measurement of the elemental concentrations within the flowing liquid. This platform aims at enhancing and facilitating the development of SPEs whose numerous experimental parameters make it time consuming to optimize and upscale. Hence, this approach solves the labour intensity issue and is as accurate as off-line Inductively Coupled Plasma, for instance. This is exemplified with a system, typical of the electronic wastes recycling industry, comprising of a mixture of Rare-Earth Elements (REEs) and Iron, whose separation is investigated as a function of various experimental parameters. It enabled us to study the performance of the newly released METALICAPT® commercial materials and to determine an optimized path towards the almost total separation of Iron from the initial mixture. Overall, the original SPE process reported herein demonstrates the platform’s reliability, performance and range of applicability.

Solid phase extraction studies on cellulose based chelating resin for separation, pre-concentration and estimation of Cu2+and Ni2+

Chelating resins based on biopolymers, specifically cellulose, offers a green analytical method for determination of metal ions at trace levels present in various samples. It offers a fast, accurate and simple method for separation and pre-concentration of metal ions at low concentrations, prior to their determination by instrumental method. Cellulose based chelating resin (CELL-GLY) has been synthesised by immobilising glycine on it. CELL-GLY was used for the determination of trace amounts of Cu2+ and Ni2+ from aqueous solutions before their determination by FAAS. The preparation of CELL-GLY involves simple steps, based on natural and easily available biopolymer cellulose, which makes its use as chelating resin is a green method. The Cu2+ and Ni2+ can be quantitatively recovered from the CELL-GLY in the pH range 4.8–6.9 and 6.9-7.8 respectively with a recovery of more than 95% for each of these metal ions. Recovery of these metal ions using CELL-GLY was quantitative up to 35 °C. The detection limits for copper and nickel by FAAS were 1.20 ppb and 1.40 ppb, respectively. The method was successfully employed for the determination of trace amounts of Cu2+ and Ni2+ in various samples.

Comparative solid phase extraction study on the U(VI) preconcentration by using immobilized thermotolerant Bacillus vallismortis and Bacillus mojavensis

Bacillus vallismortis and Bacillus mojavensis were loaded onto Amberlite XAD-4 resin and used for solid phase extraction (SPE) of uranium(VI). A quick and simple UV–Vis spectrophotometric method was used to determine U(VI) ion. The best experimental conditions were determined as being a pH of 5.0; a sample flow rate of 2.0 mL min−1; 200.0 mg of biosorbent; 800 mg of Amberlite XAD-4, and 5.0 mL of 1 mol L−1 HCl as desorption solution for both immobilized bacteria. The preconcentration factors were achieved as 80 for both solid phase extractor. The developed methods were validated by applying to reference water and tea samples.

A multivariate study of solid phase extraction of beryllium(II) using human hair as adsorbent prior to its spectrophotometric detection

A new solid phase extraction method using hair as a adsorbent has been developed for beryllium(II) prior to its spectrophotometric determination using chrome Azurol S. The effects of various variables such as pH, sample and eluent flow rates, eluent volume and concentration, sample volume, and interfering ions on the quantitative recoveries of beryllium(II) were investigated. The multivariate strategy was applied to screen out the multifactor and estimate the optimum values of experimental factors for the recovery of beryllium(II) using solid phase extraction. Calibration graph was linear in the range of 0.046–20 μg L−1 with correlation coefficient (r2 = 0.987). The sensitivity (limit of detection (LOD)) and selectivity (preconcentration factor) of the proposed methods were 0.028 and 50, respectively. Validity and accuracy of the developed solid phase extraction method were checked by analysis of a certified reference water for Trace Elements (TM-28.3) and a real water samples by standard addition method, the relative recoveries >96% were obtained. The method was successfully applied for the determination of beryllium(II) in natural water samples.

Hypercrosslinked strong anion‐exchange resin for extraction of acidic pharmaceuticals from environmental water

Two novel high-specific surface area polymeric sorbents (HXLPP-SAXa and HXLPP-SAXb) were synthesised and evaluated as solid-phase extraction sorbents. The novel sorbents under study are based on hypercrosslinked polymer microspheres and designed specifically to offer ion-exchange properties; the specific polymers of interest in the current work have been chemically modified in such a way as to impart a tuneable level of strong anion-exchange character onto the sorbents. The novel sorbents were applied as strong anion-exchange sorbents in solid-phase extraction studies, with the goal being to selectively extract a group of acidic compounds from complex environmental samples in an efficient manner. Out of two HXLPP-SAX resins evaluated in this study, it was found that the sorbent with the lower ion-exchange capacity (HXLPP-SAXa) gave rise to the best overall performance characteristics and, indeed, was found to compare favourably to the solid-phase extraction performance of commercial strong anion-exchange sorbents. When the HXLPP-SAXa sorbent was applied to the solid-phase extraction of environmental water samples, the result showed quantitative and selective extraction of low levels of acidic pharmaceuticals from 500 mL of river water and 100 mL of effluent wastewater.

XAD‐4/PAN Solid Phase Extraction System for Atomic Absorption Spectrometric Determinations of Some Trace Metals in Environmental Samples

A simple, fast, and sensitive column solid phase extraction study has been proposed for flame atomic absorption spectrometric determination of lead, cadmium, chromium, nickel, copper, and manganese ions on XAD‐4 as 1‐(2‐pyridylazo)2‐naphthol (PAN) complexes. The analytes were sorbed as PAN complexes on Amberlite XAD‐4 column at the pH range of 8.5–10, and then eluted with 1 M HNO3 in acetone. The effect of pH, reagent amount, sample volume, and matrix of the sample on the sorption of metal ions has also been investigated. The concentration of analytes after separation and preconcentration was in agreement with the added amount of ions. The present method was found to be applicable to the preconcentration of analyte ions in river water from Yesilirmak, lake water from Lake Van, bottled mineral waters, tap water, stream sediment, mushroom, tobacco, and black tea samples with good results (recoveries greater than 95%, relative standard deviations lower than 10%).

Solid-Phase Extraction Study and RP-HPLC Analysis of Lamotrigine in Human Biological Fluids and in Antiepileptic Tablet Formulations

Abstract An efficient off-line solid-phase extraction (SPE) of lamotrigine, 3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine (LTG), a new antiepileptic drug, from human serum and urine, prior to high-performance liquid chromatographic analysis, was tested and optimized. High extraction recoveries were achieved from C8 Bond Elut cartridges (200mg/3ml), using acidic acetonitrile for the elution of LTG and the internal standard, 3,5-diamino-6-(2-methoxyphenyl)-1,2,4-triazine. Isocratic reversed-phase high-performance liquid chromatographic (RP-HPLC) analysis on octylsilica, using a Lichrosorb RP-8, 5μm, 250x4.6 mm i.d. column and a mobile phase consisting of 0.05M acetate buffer pH5.6 and acetonitrile (72:28 v/v) proved to be sensitive and rapid. The identification of LTG was performed by UV detection at 306nm. The method detects approximately 0.9 ng of LTG on-column, using a 20-μl loop, and linearity holds from approximately 0.044 to 7.8 μg/ml in standard solutions. In plasma and urine, the limits of detec...

Muconaldehyde formation from 14C-benzene in a hydroxyl radical generating system

It has recently been proposed that muconaldehyde, a six carbon, α, β-unsaturated dialdehyde, may be a hematotoxic metabolite of benzene. The present studies indicate that trans-muconaldehyde is formed from benzene in vitro in a hydroxyl radical (·OH) generating system containing ascorbate, ferrous sulfate and EDTA in phosphate buffer, pH 6.7.Muconaldehyde formed from benzene in the ·OH generating system was identified by trapping it with thiobarbituric acid (TBA), which results in the formation of an adduct with a 495 nm absorption maximum and a 510 nm fluorescence emission maximum. These maxima were identical to those observed after reacting authentic trans, trans-muconaldehyde with TBA. This finding was supported by thin layer chromatography and solid phase extraction studies. In those studies benzene-derived muconaldehyde cochromatographed with the muconaldehyde/TBA standard. Analyses of the products from the ·OH generating system using high performance liquid chromatography (HPLC) confirm that trans,trans-muconaldehyde is a product of benzene ring fission. Regardledd of whether or not TBA was used for trapping, samples from the ·OH system incubated with benzene contained a peak which cochromatographed with the mucunaldehyde standard. The radioactivity profile of fractions collected during HPLC analysis demonstrates 14C-benzene to be the source of the trans,trans-muconaldehyde. The role of hydroxyl radicals in the formation of muconaldehyde was investigated by using dimethyl sulfoxide, mannitol, and ethanol as ·OH scavengers. These scavengers, at concentrations of 10 and 100 mM, were found to cause a dose-dependent decrease in the formation of muconaldehyde. This work indicates that benzene ring opening occurs in a chemical hydroxyl radical generating system, and results in the formation of a product which has the spectral and chromatographic characteristics of trans,trans-muconaldehyde.

Muconaldehyde formation from 14C-benzene in a hydroxyl radical generating system

It has recently been proposed that muconaldehyde, a six carbon, α, β-unsaturated dialdehyde, may be a hematotoxic metabolite of benzene. The present studies indicate that trans-muconaldehyde is formed from benzene in vitro in a hydroxyl radical (·OH) generating system containing ascorbate, ferrous sulfate and EDTA in phosphate buffer, pH 6.7.Muconaldehyde formed from benzene in the ·OH generating system was identified by trapping it with thiobarbituric acid (TBA), which results in the formation of an adduct with a 495 nm absorption maximum and a 510 nm fluorescence emission maximum. These maxima were identical to those observed after reacting authentic trans, trans-muconaldehyde with TBA. This finding was supported by thin layer chromatography and solid phase extraction studies. In those studies benzene-derived muconaldehyde cochromatographed with the muconaldehyde/TBA standard. Analyses of the products from the ·OH generating system using high performance liquid chromatography (HPLC) confirm that trans,trans-muconaldehyde is a product of benzene ring fission. Regardledd of whether or not TBA was used for trapping, samples from the ·OH system incubated with benzene contained a peak which cochromatographed with the mucunaldehyde standard. The radioactivity profile of fractions collected during HPLC analysis demonstrates 14C-benzene to be the source of the trans,trans-muconaldehyde. The role of hydroxyl radicals in the formation of muconaldehyde was investigated by using dimethyl sulfoxide, mannitol, and ethanol as ·OH scavengers. These scavengers, at concentrations of 10 and 100 mM, were found to cause a dose-dependent decrease in the formation of muconaldehyde. This work indicates that benzene ring opening occurs in a chemical hydroxyl radical generating system, and results in the formation of a product which has the spectral and chromatographic characteristics of trans,trans-muconaldehyde.