Molecularly imprinted polymers based enrichment and separation for trace analysis in capillary electrophoresis.

Capillary electrophoresis (CE) is well known for its high resolution, rapidity, low sample and reagent consumption, and ability to simply change separation modes, and has been widely used for separation and detection of various analytes important for many fields. One major limitation is the concentration limits of detection, which can be further worsened in complex samples with a significant matrix component. Molecularly imprinted polymers (MIPs) based solid-phase extraction (SPE) and stationary phases (SPs) enjoy great popularity in CE, owing to the recognition specificity, physical robustness, thermal stability, as well as low cost and easy preparation of MIPs.

On-line preconcentration and analysis of neutral propiconazole and atrazine in wheat flour by micelle to cyclodextrin stacking-micellar electrokinetic chromatography.

Online micelle to cyclodextrin stacking (MCDS) was demonstrated to preconcentrate neutral propiconazole enantiomers and atrazine, followed by separation under suppressed EOF MEKC. Stacking occurred at the boundary between SDS micelle-bound analytes and neutral alpha-cyclodextrin (α-CD), where the analytes were released upon formation of inclusion complexes between SDS micelles and α-CD. The SDS concentration in the sample matrix, the ratio of α-CD and sample solution injection time, and the electrokinetic sample injection voltage during MCDS were optimized.

Closed-loop peristaltic micro-pump for flow-through sample injection in capillary electrophoresis.

Capillary electrophoresis (CE) is increasingly used in distributed field environmental monitoring, teaching, and citizen science. Consequently, the development of low-cost CE instruments using inexpensive components and do-it-yourself approaches has gained significant attention. Peristaltic micro-pumps (PMPs), with dimensions as small as 15 × 17 × 34 mm, offer advantages such as low cost, compact size, and energy efficiency, making them highly suitable for miniaturized CE instruments with automated flow-through injection.

Advancements in Multiple-Step On-Line Preconcentration Techniques for Enhanced Sensitivity in Capillary Electrophoresis.

Multiple-step on-line preconcentration, a combination of at least two stacking techniques has been developed to increase the sensitivity in capillary electrophoresis (CE) for analytes in various samples. It is usually conducted sequentially, or in some cases, synergistically, where different stacking modes occur simultaneously. Multiple-step techniques allow simultaneous preconcentration and separation of various kinds of analytes in different complex samples in a single CE run.

Tailoring molecularly imprinted polymer on titanium-multiwalled carbon nanotube functionalized gold electrode for enhanced chlorophyll determination in microalgae health assessment.

A unique method for determining chlorophyll content in microalgae is devised employing a gold interdigitated electrode (G-IDE) with a 10-µm gap, augmented by a nano-molecularly imprinted polymer (nano-MIP) and a titanium dioxide/multiwalled carbon nanotube (TiO/MWCNT) nanocomposite. The nano-MIP, produced using chlorophyll template voids, successfully trapped chlorophyll, while the TiO/MWCNT nanocomposite, synthesized by the sol-gel technique, exhibited a consistent distribution and anatase crystalline structure. The rebinding of procured chlorophyll powder, which was used as a template for nano-MIP synthesis, was identified with a high determination coefficient (R = 0.

Nanoplastic Sample Cleanup by Micro-Electromembrane Extraction across Free Liquid Membranes.

Sample preparation techniques enabling the separation and cleanup of nanoplastics removing other components present in complex sample matrices are scarce. Herein, micro-electromembrane extraction (μ-EME) has been explored for this purpose based on the extraction of nanoplastic particles across a free liquid membrane (FLM). The extraction unit is based on a perfluoroalkoxy tube sequentially filled with the acceptor solution (20 μL 5 mM phosphate buffer, pH 10.

Methamphetamine detection using portable capillary electrophoresis coupled with a swab-based extraction device.

Methamphetamine (MA) is one of the most virulent illicit drugs that can be synthesized from household materials leading to its prevalent trafficking and local manufacturing in clandestine drug laboratories (clan labs). The significant problems of tracing MA in clan labs and monitoring drug abusers lie in the lag time between sample collection and analysis and the number of tests done. Capillary electrophoresis (CE) is a rapid separation technique amenable to miniaturization and field testing.

Isotachophoretic quantification of total viable bacteria on meat and surfaces.

Background: The quantification of microbes, particularly live bacteria, is of utmost importance in assessing the quality of meat products. In the context of meat processing facilities, prompt identification and removal of contaminated carcasses or surfaces is crucial to ensuring the continuous production of safe meat for human consumption. The plate count method and other traditional detection methods are not only labour-intensive but also time-consuming taking 24-48 h.

Bidimensional Dynamic Magnetic Levitation: Sequential Separation of Microplastics by Density and Size.

There is a current gap in sample preparation techniques integrating the separation of microplastics according to their different material types and particle sizes. We describe herein the Bidimensional Dynamic Magnetic Levitation (2D-MagLev) technique, enabling the resolution of mixtures of microplastics sorting them by plastic type and particle size. Separations are carried out in a bespoke flow cell sandwiched between two ring magnets and connected to programmable pumps for flow control.

Isolation and Identification of the High-Affinity DNA Aptamer Target to the Brain-Derived Neurotrophic Factor (BDNF).

Aptamers are functional oligonucleotide ligands used for the molecular recognition of various targets. The natural characteristics of aptamers make them an excellent alternative to antibodies in diagnostics, therapeutics, and biosensing. DNA aptamers are mainly single-stranded oligonucleotides (ssDNA) that possess a definite binding to targets.

Chemical vapour deposition in narrow capillaries: Electro-osmotic flow control in capillary electrophoresis.

Background: In capillary electrophoresis (CE), the inner surface of fused-silica capillaries is commonly covalently modified with liquid silanes to control electroosmotic flow (EOF). This liquid phase deposition (LPD) approach is challenging for long and narrow-diameter capillaries (≥1 m, ≤25 μm ID) inhibiting commercial production. Here, we use chemical vapour deposition (CVD) to covalently modify capillaries with different silanes.

Electrokinetic Extraction of Doxorubicin from Biological Fluids by Polymer Inclusion Membrane Sampling Probe.

A polymer inclusion membrane (PIM) based sampling probe was developed for electrokinetic extraction of drugs from biological fluids. The probe was fabricated by dip-coating a nonconductive glass capillary tube in a homogeneous PIM solution for three cycles. The PIM solution comprised cellulose triacetate (CTA), 2-nitrophenyl octyl ether (NPOE), and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [EMIM][NTf] in a ratio of 5:4:2.

Portable capillary electrophoresis coupled with swab-based extraction device for cleaning validation in pharmaceutical facilities.

All pharmaceutical manufacturers are required to verify that their production equipment is free from contaminants. Here, we report the capability of a fully automated portable capillary electrophoresis instrument with an integrated sample swab extraction - the Grey Scan ETD-100 - for the detection of pharmaceutical residues on surfaces of manufacturing equipment. Lidocaine was used as a model compound and could be recovered from a surface by swabbing, extracted from the swab, and analysed within 1 min.

Magnetism-Assisted Density Gradient Separation of Microplastics.

A versatile method for the efficient separation of different types of microplastics from particle mixtures is presented. Magnetism-assisted density gradient separation (Mag-DG-Sep) relies on a bespoke separation cell connected to a gradient pump and located between two like-pole-facing neodymium magnets. In Mag-DG-Sep, particle mixtures initially sunk in water are subjected to a gradient of increasing concentration of MnCl, enabling the sequential suspension and collection of particles with different densities.

Development of dispersive inclusion complex microextraction for the analysis of nitrosamines in medicinal products.

A new dispersive inclusion complex microextraction (DICM) approach coupled with ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for the determination of n-nitrosamine impurities in different medicinal products is demonstrated for the first time. The proposed DICM procedures consist of a dispersive liquid phase microextraction steps employing cyclodextrin as an inclusion complex agent to extract n-nitrosamines namely N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodiisopropylamine (NDIPA), N-ethyl-N-nitrosoisopropylamine (NEIPA) and N-nitroso-di-n-butylamine (NDBA) present in the medicinal products. The sample solutions were prepared by mixing 5% (m/v) NaCl solution with 1.

Biphasic Magnetic Levitation to Detect Organic Pollutants on Microplastics.

Microplastics have the potential to adsorb organic pollutants due to their lipophilic nature. Evaluating the distribution of multiple organic pollutants in different types of microplastics coexisting in a sample is a strenuous and challenging analytical task. Here, we report position-dependent microplastic trapping in a biphasic medium comprising a paramagnetic aqueous donor phase containing the mixed microplastics and a diamagnetic organic acceptor phase.

Miniaturized 3D printed solid-phase extraction cartridges with integrated porous frits.

Here we have studied the effect of the thickness and printing orientation using PolyJet 3D printing to fabricate single-material cartridges with built-in porous frits enabling solid-phase extraction (SPE) by packing commercial sorbents. This is achieved by tuning the degree of interpenetration of the building material and the water-soluble support material used in PolyJet 3D printing by modifying the orientation of the print head respective to the frit. SPE cartridges printed at an orientation of 30° with a 150 μm thick integrated frit were selected for the SPE experiments in a compromise between frit permeability to flow and stability to retain commercial sorbents for SPE.

Inexpensive portable capillary electrophoresis instrument for Monitoring Zinc(II) in remote areas.

A compact, inexpensive capillary electrophoresis instrument was developed for monitoring metal ions and evaluated for Zn(II) in remote contaminated locations in western Tasmania, Australia. The portable instrument, measuring 21 cm x 10 cm x 7 cm, was powered from the USB port of a laptop computer and built from off-the-shelf components costing ∼$1200 USD. Electrophoretic separations were conducted using a fused silica capillary (10-50 µm I.

Isotachophoresis for rapid transformation of Escherichia coli.

A frequent limitation of electroporation (EP) and chemical transformation (CT) are the need of tedious and time-consuming procedures for inducing transformation competence, the substantial number of cells required, and the low transformation yields typically achieved. Here, we show a new and rapid electrokinetic method for transformation of small number of noncompetent Escherichia coli TOP10 cells (2-3 × 10 ) at room temperature. Escherichia coli TOP10 cells and plasmid DNA are sequentially injected into a 50 μm ID capillary and focused into 11.

Porphyrin-based colorimetric sensing of perfluorooctanoic acid as proof of concept for perfluoroalkyl substance detection.

A functionalized porphyrin receptor was prepared to bind perfluorooctanoic acid. UV-Vis spectroscopic analysis showed the receptor gave a rapid colorimetric response that could also be detected visually at environmentally relevant concentrations. Spiked soil samples were used to demonstrate detection of perfluorooctanoic acid without intensive sample pre-treatment or laboratory instrument analysis.

Hyphenated sample preparation-electrospray and nano-electrospray ionization mass spectrometry for biofluid analysis.

Stand-alone electrospray ionization mass spectrometry (ESI-MS) has been advancing through enhancements in throughput, selectivity and sensitivity of mass spectrometers. Unlike traditional MS techniques which usually require extensive offline sample preparation and chromatographic separation, many sample preparation techniques are now directly coupled with stand-alone MS to enable outstanding throughput for bioanalysis. In this review, we summarize the different sample clean-up and/or analyte enrichment strategies that can be directly coupled with ESI-MS and nano-ESI-MS for the analysis of biological fluids.

Automated liquid-liquid extraction of organic compounds from aqueous samples using a multifunction autosampler syringe.

Liquid-liquid extraction is one of the most widely used and simplest sample preparation techniques. However, consumption of large volumes of organic solvent and manual handling are two major drawbacks of this technique. A multifunction autosampler syringe is introduced which permits automated liquid-liquid extraction in an enclosed operating environment, with low consumption of organic solvents.

Scalable 3D printing method for the manufacture of single-material fluidic devices with integrated filter for point of collection colourimetric analysis.

Assembly and bonding are major obstacles in manufacturing of functionally integrated fluidic devices. Here we demonstrate a single-material 3D printed device with an integrated porous structure capable of filtering particulate matter for the colourimetric detection of iron from soil and natural waters. Selecting a PolyJet 3D printer for its throughput, integrated filters were created exploiting a phenomenon occurring at the interface between the commercially available build material (Veroclear-RGD810) and water-soluble support material (SUP707).

An electrophoretic ion analyzer for on-site autonomous water monitoring.

An on-site ion analyzer based on capillary electrophoresis with pressure-driven flow through injection and capacitively coupled contactless conductivity detection has been developed for field monitoring of cations and anions in environmental waters. Automated time-pressure based hydrodynamic injection provides stable pL-nL scale injection (RSD = 1.96%, n = 30).