The determination of zinc using flow injection and continuous flow analysis combined with a polymer inclusion film-coated column: Application to the determination of zinc in alloys and commercial lithium chloride.

A column coated with a polymer inclusion film (PIF) containing Aliquat 336 as carrier cast on glass beads packed in a glass tube is described for the separation, preconcentration, and determination of zinc(II) in flow injection analysis (FIA) and continuous flow analysis (CFA) systems. In the FIA method, 200 μL of a sample solution containing 2 mol/L lithium chloride is injected into a 2 mol/L lithium chloride stream. This converts zinc(II) ion into its anionic chlorocomplexes which are then extracted into the Aliquat 336-based PIF by anion exchange.

Microfluidic Fabrication of Micropolymer Inclusion Beads for the Recovery of Gold from Electronic Scrap.

A composite material, referred to as micropolymer inclusion beads (μPIBs), was fabricated for the first time using a microfluidic technique and applied successfully for the recovery of Au(III) from simulated digests of electronic scrap. Best results for the extraction of Au(III) were achieved with μPIBs consisting of 55% (m/m) poly(vinyl chloride) as the base polymer, 35% (m/m) Aliquat 336 as the extractant, and 10% (m/m) 1-tetradecanol as a modifier. The size and surface morphology of the μPIBs were examined using optical microscopy and scanning electron microscopy, respectively.

A cross-linked polymer inclusion membrane for enhanced gold recovery from electronic waste.

A cross-linked polymer inclusion membrane (CL-PIM) incorporating the extractant trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate (Cyphos® IL 104) was developed for the first time for the enhanced Au(III) recovery from aqua regia digests of electronic waste (discarded mobile phones). Cellulose triacetate (CTA), poly(vinyl chloride) (PVC) and poly(vinylidene fluoride-co-hexafluropropylene) (PVDF-HFP) were examined as base polymers. The suitability of poly(ethylene glycol) dimethylacrylate (PEGDMA), poly(ethylene glycol) divinyl ether (PEGDVE) and N-ethylmaleimide (NEM) as cross-linking agents, and the possibility of using triarylsulfonium hexafluorophosphate (TASHFP) and 2,2-dimethoxy-2-phenylacetophenone (DMPA) as initiators were investigated.

Automatic determination of arsenate in drinking water by flow analysis with dual membrane-based separation.

The sequential application of a polymer inclusion membrane (PIM), composed of poly(vinylidenefluoride-co-hexafluoropropylene) and the anionic extractant Aliquat 336, and a microporous polytetrafluoroethylene (PTFE) gas-permeable membrane was utilized for the first time to develop a flow analysis (FA) system, for the automatic determination of trace levels of arsenate (As(V)) in drinking water as arsine. The system incorporated a flow-through extraction cell for separation and preconcentration of arsenate and a gas-diffusion cell for the separation of arsine prior to its spectrophotometric determination based on the discoloration of a potassium permanganate solution. Under optimal conditions the FA system is characterized by a limit of detection of 3.

Flow injection spectrophotometric determination of V(V) involving on-line separation using a poly(vinylidene fluoride-co-hexafluoropropylene)-based polymer inclusion membrane.

A poly(vinylidene fluoride-co-hexafluoropropylene)-based polymer inclusion membrane (PIM) using Cyphos® IL 101 (i.e. trihexyl(tetradecyl)phosphonium chloride) as the carrier and 2-nitrophenyl octyl ether as a plasticizer in a mass ratio of 55/35/10 was employed for the on-line extractive separation of V(V) prior to its spectrophotometric determination in a flow injection analysis (FIA) system using xylenol orange as the colorimetric reagent.

The Effect of Surface Confined Gold Nanoparticles in Blocking the Extraction of Nitrate by PVC-Based Polymer Inclusion Membranes Containing Aliquat 336 as the Carrier.

Clusters of gold nanoparticles (AuNPs) formed on the surface of PVC-based polymer inclusion membranes (PIMs) with a liquid phase containing Aliquat 336 as the carrier and in some cases 1-dodecanol or 2-nitrophenol octyl ether as plasticizers were found to inhibit the extraction of nitrate by the PIMs. This observation was based on gradually increasing the mass of AuNPs on the membrane surface and testing the ability of the membrane to extract nitrate after each increase. In this way, it was possible to determine the so-called "critical AuNP masses" at which the studied membranes ceased to extract nitrate.

Fast and Environmentally Friendly Microfluidic Technique for the Fabrication of Polymer Microspheres.

This paper reports on a novel microfluidic technique for the fabrication of microspheres of synthetic polymers including poly(vinyl chloride) (PVC), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(lactic acid) (PLA), and polystyrene (PS). The polymers are dissolved in tetrahydrofuran (THF) and the method is based on the diminished solubility of THF in a 20% (w/v) NaCl solution which allows the formation of droplets of the polymer solution. These polymer solution droplets are generated in a microfluidic system and their desolvation is accomplished within seconds by allowing the droplets to rise by buoyancy through a NaCl solution with a concentration lower than 15%.

Polymer inclusion membranes (PIMs) in chemical analysis - A review.

This review highlights the increasing interest in polymer inclusion membranes (PIMs) in analytical chemistry as they are adapted to new and novel applications. PIMs are polymer-based liquid membranes and were first introduced 50 years ago as the sensing membranes in ion-selective electrodes and optodes. More recently however, PIMs have been used for other applications in analytical chemistry such as for sample separation, sample pre-concentration, electro-driven extraction, and passive sampling, and have also been incorporated into on-line and automated analysis systems.

A novel polymer inclusion membrane based method for continuous clean-up of thiocyanate from gold mine tailings water.

Thiocyanate is present in gold mine tailings waters in concentrations up to 1000mgL and this has a serious environmental impact by not allowing water reuse in the flotation of gold ore. This significantly increases the consumption of fresh water and the amount of wastewater discharged in tailings dams. At the same time thiocyanate in tailings waters often leads to groundwater contamination.

Improvement of Chromium(VI) Extraction from Acidic Solutions Using a Poly(vinyl chloride)-based Polymer Inclusion Membrane with Aliquat 336 as the Carrier.

An important reason for the inefficient extraction of Cr(VI) from its acidic solutions into polymer inclusion membranes (PIMs), consisting of poly(vinyl chloride) as the base-polymer and Aliquat 336 as the carrier, was found to be associated with the leaching of Aliquat 336 from the PIMs into the solutions, where it subsequently reduced the anionic Cr(VI) species to cationic Cr(III) species. The PIM extraction efficiency for Cr(VI) was significantly improved by the addition of NaNO to the solutions, which suppressed the leaching of Aliquat 336 and the reduction of Cr(VI) to Cr(III).

Colorimetric detection based on localised surface plasmon resonance of gold nanoparticles: Merits, inherent shortcomings and future prospects.

Localised surface plasmon resonance (LSPR) of gold nanoparticles (AuNPs) has been exploited for two decades in analytical science and has proven to be a powerful tool for the detection of various kinds of substances including small molecules, ions, macro biomolecules and microbes. Detection can be performed by visual colour change observations, photometry or resonance light scattering. A wide range of applications have been studied in the areas of environmental, pharmaceutical and biological analysis and clinical diagnosis.

Development of a passive sampler based on a polymer inclusion membrane for total ammonia monitoring in freshwaters.

A passive sampler for determining the time-weighted average total ammonia (i.e. molecular ammonia and the ammonium cation) concentration (C TWA) in freshwaters, which incorporated a polymer inclusion membrane (PIM) as a semi-permeable barrier separating the aqueous source solution from the receiving solution (i.

Extraction of Gold(III) from Hydrochloric Acid Solutions with a PVC-based Polymer Inclusion Membrane (PIM) Containing Cyphos(®) IL 104.

Poly(vinyl chloride) (PVC) based polymer inclusion membranes (PIMs), with different concentrations of Cyphos® IL 104 as the membrane extractant/carrier, were studied for their ability to extract Au(III) from hydrochloric acid solutions. Some of the PIMs also contained one of the following plasticizers or modifiers: 2-nitrophenyloctyl ether, dioctylphthalate, 1-dodecanol, 1-tetradecanol, or tri(2-ethylhexyl) phosphate. The best performance, in terms of extraction rate and amount of Au(III) extracted, was exhibited by a PIM consisting of 25 wt% Cyphos(®) IL 104, 5 wt% 1-dodecanol, and 70 wt% PVC.

The use of a polymer inclusion membrane as a sorbent for online preconcentration in the flow injection determination of thiocyanate impurity in ammonium sulfate fertilizer.

A polymer inclusion membrane (PIM) is used for the first time as a sorbent in the construction of a preconcentration column to enhance the sensitivity in flow injection analysis (FIA). The PIM-coated column is readily prepared by coating the PIM containing poly(vinyl chloride), Aliquat 336, and 1-tetradecanol onto glass beads packed in a glass tube. The determination of trace amounts of thiocyanate in ammonium sulfate fertilizer demonstrates the potential of the proposed PIM-coated column in FIA.

Development of a passive sampler for Zinc(II) in urban pond waters using a polymer inclusion membrane.

The use of a polymer inclusion membrane (PIM) in a novel passive sampler to measure the time-weighted average concentration of Zn(II) in urban waters is described. The passive sampler consists of a compartment containing an acidic receiving solution, which is separated from the external source solution by a PIM consisting of 40 wt% di-2-(ethylhexyl) phosphoric acid as the extractant, and 60 wt% poly-(vinyl chloride) as the base polymer. Two laboratory passive sampling techniques were tested.

Imaging chemical extraction by polymer inclusion membranes using fluorescence microscopy.

Polymer inclusion membranes (PIMs) transport chemicals between bodies of liquid by simultaneously performing chemical extraction and back-extraction. The internal chemical and physical mechanisms by which this transport occurs are, however, poorly understood. Also, some PIMs, which are otherwise optimal for their task, age and lose function after only days, limiting their feasibility for industrial upscaling.

The use of a polymer inclusion membrane in a paper-based sensor for the selective determination of Cu(II).

A disposable paper-based sensor (PBS) is described for the determination of Cu(II) in natural and waste waters at approximately 2 cents per measurement. The device makes use of a polymer inclusion membrane (PIM) to provide the selectivity for Cu(II). The PIM consists of 40 wt% di(2-ethlyhexyl) phosphoric acid (D2EHPA) as the carrier, 10 wt% dioctyl phthalate (DOP) as a plasticizer, 49.

The use of a polymer inclusion membrane for separation and preconcentration of orthophosphate in flow analysis.

A highly sensitive flow analysis system has been developed for the trace determination of reactive phosphate in natural waters, which uses a polymer inclusion membrane (PIM) with Aliquat 336 as the carrier for on-line analyte separation and preconcentration. The system operates under flow injection (FI) and continuous flow (CF) conditions. Under optimal FI conditions the system is characterised by a linear concentration range between 0.

On-line extractive separation in flow injection analysis based on polymer inclusion membranes: a study on membrane stability and approaches for improving membrane permeability.

The effect of temperature on the sensitivity and sampling rate is studied for a flow injection analysis (FIA) system that uses a membrane separation cell fitted with a polymer inclusion membrane (PIM) for the determination of Zn(II). A temperature of 50 °C for the flowing donor and acceptor solutions and the membrane separation cell improves the sensitivity and the sampling rate relative to 20 °C up to 10-fold and 2-fold, respectively. Studies on the stability of the PIM are reported that show a limited loss of the membrane liquid phase into the aqueous phases used in the FIA system but this has exhibited a negligible effect on the amount of Zn(II) transported across the membrane.

Solid-phase extraction of cobalt(II) from lithium chloride solutions using a poly(vinyl chloride)-based polymer inclusion membrane with Aliquat 336 as the carrier.

The extraction of cobalt(II) from solutions containing various concentrations of lithium chloride, hydrochloric acid, and mixtures of lithium chloride plus hydrochloric acid is reported using a poly(vinyl chloride) (PVC)-based polymer inclusion membrane (PIM) containing 40% (w/w) Aliquat 336 as a carrier. The extraction from lithium chloride solutions and mixtures with hydrochloric acid is shown to be more effective than extraction from hydrochloric acid solutions alone. The solution concentrations giving the highest amounts of extraction are 7 mol L(-1) for lithium chloride and 8 mol L(-1) lithium chloride plus 1 mol L(-1) hydrochloric acid for mixed solutions.

The use of a polymer inclusion membrane in flow injection analysis for the on-line separation and determination of zinc.

This paper reports the first use of a polymer inclusion membrane (PIM) for on-line separation in flow injection analysis (FIA) involving simultaneous extraction and back-extraction. The FIA system containing the PIM separation module was used for the determination of Zn(II) in aqueous samples in the presence of Mg(II), Ca(II), Cd(II), Co(II), Ni(II), Cu(II), and Fe(III). The Fe(III) and Cu(II) interferences were eliminated by off-line precipitation with phosphate and on-line complexation with chloride, respectively.

Mathematical modeling of a Nafion membrane based optode incorporating 1-(2'-pyridylazo)-2-naphthol under flow injection conditions.

A general mathematical model of a flow-through optical chemical sensor prepared by the immobilization of 1-(2'-pyridylazo)-2-naphthol (PAN) into a commercial Nafion membrane was developed. The model takes into account the preparation of the optode membrane and in our opinion the most important chemical and physical processes involved in the generation of the analytical signal. The following model parameters were determined separately from the experimental verification of the model: aqueous diffusion coefficient of CuSO(4) - 8.

Voltammetric ion-selective electrodes for the selective determination of cations and anions.

A general theory has been developed for voltammetric ion sensing of cations and anions based on the use of an electrode coated with a membrane containing an electroactive species, an ionophore, and a supporting electrolyte dissolved in a plasticizer. In experimental studies, a membrane coated electrode is fabricated by the drop coating method. In one configuration, a glassy carbon electrode is coated with a poly(vinyl chloride) based membrane, which contains the electroactive species, ionophore, plasticizer and supporting electrolyte.

Determination of arsenic in industrial samples by pervaporation flow injection with amperometric detection.

This paper describes a simple and inexpensive pervaporation flow injection (PFI) system for the on-line determination of arsenic in industrial samples based on amperometric detection. The PFI system uses on-line hydride generation for the separation of As(III) from the sample matrix thus substantially reducing matrix interferences associated with "dirty" industrial samples. A method for the speciation of As(III) and As(V) is also described.