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Abstract: Portable and field deployable analytical instruments are attractive in many fields including medical diagnostics, where point of care and on-site diagnostics systems capable of providing rapid quantitative results have the potential to vastly improve the productivity and the quality of medical care. Isotachophoresis (ITP) is a well known electrophoretic separation technique previously demonstrated as suitable for miniaturization in microfluidic chip format (chip-ITP). In this work, a purpose-designed ITP chip compatible with a commercial end-used targeted microfluidic system was used to study different injection protocols and to evaluate the effect of the length of the separation channel on the analytical performance. The in-house ITP chips were made from Corning glass and compared to the commercial DNA chip for the ITP separation of anions from the hydrodynamic injection of human serum. Using the in-house ITP chip the isotachophoretic step of lactate from human serum was approximately two times longer. The results of this research suggested that microfluidic ITP with indirect fluorescence detection is a viable technique for separation of organic acids in human serum samples, especially when a chip with suitable design is used. [Copyright &y& Elsevier]

A new 3D printable resin formulation is developed and optimized from commercially available thiol (pentaerythritol tetrakis(3‐mercaptopropionate); PETMP) and alkyne (3‐butyn‐1‐ol; BA) monomers. Printed objects are characterized by Fourier‐transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The extraction efficiency of the printed thiol‐yne device is then investigated using a model dye – malachite green (MG). The results displayed excellent dye removal efficiency with > 95% MG removed within 5 min. The 3D‐printed devices are reusable and show 100% removal over six cycles after washing with deionized water and methanol. The presence of surface hydroxyl groups derived from the BA monomer is shown to enhance dye adsorption in comparison to control materials. The printing procedure and resin formulation are robust and consistent when devices from different resin batches are compared for MG dye removal. The thiol‐yne 3D printed devices demonstrated excellent dye removal (> 99%) from water samples collected from a tap and a nearby river source. The successful development of this resin provides a new thiol‐yne‐based resin system for stereolithography (SLA) 3D printing for the removal of organic dyes from wastewater and presents a potential for broad applications in water treatment. [ABSTRACT FROM AUTHOR]

Abstract: Capillary electrophoresis (CE) has long been regarded as a powerful analytical separation technique that is an alternative to more traditional methods such as gel electrophoresis (GE) and liquid chromatography (LC). It is often touted as having a number of advantages over both of these, such as speed, flexibility, portability, sample and reagent requirements and cost, but also a number of disadvantages such as reproducibility and sensitivity. Microchip electrophoresis (ME), the next evolutionary step, miniaturised CE further providing improvements in speed and sample requirements as well as the possibility to perform more complex and highly integrated analyses. CE and ME are seen as a viable alternative to GE, but are often considered to be inferior to LC. This review will consider the strengths and weaknesses of both CE and ME and will challenge the common conceptions held about these. [Copyright &y& Elsevier]

Online sample concentration or stacking of basic drugs by transient isotachophoresis with the injection of an acid in co-electroosmotic flow capillary zone electrophoresis was studied experimentally and with computer simulation. The acid stacking strategy afforded an order of magnitude improvement in concentration sensitivity for model tricyclic antidepressant and β blocker drugs. [ABSTRACT FROM AUTHOR]

Abstract: Liquid–liquid microextraction using the water immiscible ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, EMIM NtfO2, for the concentration and cleanup of basic compounds for analysis by CE has been investigated. Using an electrolyte comprising 1mol/L alanine and 3mol/L acetic acid, EMIM NtfO2 could be directly injected into the capillary after liquid phase extraction. Using the basic dye chryisoidine, sensitivity enhancements approaching 1000-fold were obtained by mixing 20μL of EMIM NtfO2 with 1500μL of aqueous sample, leaving only 5μL of the undissolved ionic liquid which was used for injection into the CE. Lower more repeatable enhancement factors of 200-fold were obtained with slightly larger initial 25μL volumes of EMIM NtfO2 due to the larger residual volume of ionic liquid which made handling easier. This could be extended to basic pharmaceuticals, and the extraction of clozapine and its two active metabolites, nor-clozapine and clozapine-N-oxide, was demonstrated from urine with enrichment factors greater than 100 obtained. Handling of potentially more dangerous samples, such as serum, through in-vial extraction of clozapine and its metabolites and direct injection of the ionic liquid layer was also demonstrated with enhancements in sensitivity of 80. Limits of detection from 3 to 11μg/L and 6 to 55μg/L were obtained from urine and serum, respectively, which are sufficiently low to be useful for the determination of these pharmaceuticals clinically for therapeutic drug monitoring and for forensic toxicology. [Copyright &y& Elsevier]

Abstract: Electrokinetic supercharging (EKS), a new and powerful on-line preconcentration method for capillary electrophoresis, was utilized in non-aqueous capillary electrophoresis (NACE) to enhance the sensitivity of phenolic acids. The buffer acidity and concentration, leader and terminator length and electrokinetic injection time were optimised, with the optimum conditions being: a background electrolyte of 40mM Tris–acetic acid (pH 7.9), hydrodynamic injection of 50mM ammonium chloride (22s, 0.5psi) as leader, electrokinetic injection of the sample (180s, −10kV), hydrodynamic injection of 20mM CHES (32s, 0.5psi) as terminator, before application of the separation voltage (−25kV). Under these conditions the sensitivity was enhanced between 1333 and 3440 times when compared to a normal hydrodynamic injection with the sample volume <3% of the capillary volume. Detection limits for the seven phenolic acids were in the range of 0.22–0.51ng/mL and EKS was found to be 3.6–7.9 times more sensitive than large-volume sample stacking and anion selective exhaustive injection for the same seven phenolic acids. [Copyright &y& Elsevier]

Abstract: In this work, two significant advances in photolithographic patterning of polyaniline (PANI) films are reported. Firstly, flash welding was enhanced through the use of polymeric substrates, enabling complete penetration of the welding of PANI films with thicknesses ranging from 5 to over 14μm, significantly thicker than reported previously. Masking of parts of the PANI films during flash welding enabled the formation of adjacent conducting and insulating regions as the welding changes the electrical properties of the film. Raman spectroscopy was used to determine the sharpness of these edges, and indicated that the interface between the flash welded and masked regions of the PANI films was typically less than 15μm wide. Secondly, using longpass filters, light with a wavelength less than 570nm was found not to contribute to the welding process. This was confirmed by the use of a 635nm laser diode for welding the PANI films. This novel approach enabled patterning of PANI films using a direct writing technique with a narrow wavelength light source. [Copyright &y& Elsevier]

Abstract: An EOF counter-balanced ITP boundary has been used to stack anions from high conductivity samples during continuous electrokinetic injection of the sample. In a polystyrenesulfonate/poly(diallyldimethylammonium chloride) polyelectrolyte coated capillary, the time at which the ITP boundary exited the capillary could be prolonged by balancing the movement of the boundary with the EOF. Using a bis-tris-propane electrolyte, the ITP boundary was removed from the capillary within 7min, while when using triethanolamine the ITP boundary was still at 30% of the capillary after 2h of injection. Using these systems, the sensitivity of a mixture of simple organic acids in 100mM Cl− was improved by 700–800-fold using bis-tris-propane with a whole-capillary injection of the sample and 5min of electrokinetic injection at +28kV, and 1100–1300-fold using triethanolamine and 60min of electrokinetic injection under the same conditions. The potential of the method to be applicable to high conductivity samples was demonstrated by stacking a whole capillary filled with urine spiked with naphthalenedisulfonic acid, with limits of detection 450 times lower than those achievable with a normal hydrodynamic injection. [Copyright &y& Elsevier]

Abstract: Three strategies were investigated for the simultaneous separation and on-line preconcentration of charged and neutral hypolipidaemic drugs in micellar electrokinetic chromatography (MEKC). A background electrolyte (BGE) consisting of 20mM ammonium bicarbonate buffer (pH 8.50) and 50mM sodium dodecyl sulfate (SDS) was used for the separation and on-line preconcentration of the drugs. The efficiencies of sweeping, analyte focusing by micelle collapse (AFMC), and simultaneous field-amplified sample stacking (FASS) and sweeping, were compared for the preconcentration of eight hypolipidaemic drugs in different conductivity sample matrices. When compared with a hydrodynamic injection (5s at 50mbar, 0.51% of capillary volume to detection window) of drug mixture prepared in the separation BGE, improvements of detection sensitivity of 60-, 83-, and 80-fold were obtained with sweeping, AFMC and simultaneous FASS and sweeping, respectively, giving limits of detection (LODs) of 50, 36, and 38μg/L, respectively. The studied techniques showed suitability for focusing different types of analytes having different values of retention factor (k). This is the first report for the separation of different types of hypolipidaemic drugs by capillary electrophoresis (CE). The three methods were validated then applied for the analysis of target analytes in wastewater samples from Hobart city. [Copyright &y& Elsevier]

Abstract: Polymeric ion-exchange monoliths typically exhibit low capacities due to the limited surface area on the globules of the monoliths. The ion-exchange binding of protonated weakly basic analytes on deprotonated carboxylate sites on methacrylate polymer monoliths has been increased by templating the monoliths with silica nanoparticles. The templating method is achieved by adding the nanoparticles as a suspension to the polymerisation mixture. After polymerisation, the nanoparticles are removed by washing the monolith with strong base. Monolithic columns prepared using this procedure have exhibited a 33-fold increase in ion-exchange capacity when compared to untemplated monoliths prepared and treated under similar conditions. The templating procedure does not alter the macroporous properties of the polymer monolith, confirmed through scanning electron microscopy and BET surface area analysis, but provides increased capacity predominantly through the re-orientation of more carboxylic acid groups. The resulting increase in ion-exchange capacity has proven to be useful for the preconcentration and separation of neurotransmitters by in-line solid-phase extraction–capillary electrophoresis. The increased capacity of the templated monolith allowed the injection time to be increased 10 times over that of an untemplated monolith, allowing 10 times more sample to be injected with the efficiencies and recoveries remaining unaffected. The enhancement in sensitivity for the test mixture of neurotransmitter (dopamine, norepinephrine and metanephrine) ranged 1500–1900 compared to a normal hydrodynamic injection in capillary electrophoresis. Efficiencies obtained for the neurotransmitters were 100000–260000 plates, typical of those obtained in capillary zone electrophoresis. The applicability of the increased capacity silica nano-templated polymer monolith was demonstrated by analysing trace levels of caffeine in biological, food and environmental samples. [Copyright &y& Elsevier]

Abstract: Electrokinetic supercharging (EKS) has been used in the last few years as a powerful tool for separation and on-line preconcentration of different types of analytes. We have developed a valuable modification for EKS system, namely counter-flow EKS (CF-EKS) and applied it for the separation and on-line preconcentration of seven non-steroidal anti-inflammatory drugs (NSAIDs) in water samples. In CF-EKS, a hydrodynamic counter-flow is applied during electrokinetic injection of the analytes within the EKS system. This counter-flow minimises the introduction of the sample matrix into the capillary, allowing longer injections to be performed. Careful choice of the optimum counter-flow as well as the optimum injection voltage allowed the sensitivity to be enhanced by 11,800-fold, giving limits of detection (LODs) of 10.7–47.0ng/L for the selected NSAIDs. The developed method was validated and then applied for the determination of the studied NSAIDs in drinking water as well as wastewater samples from Hobart city. [Copyright &y& Elsevier]

Abstract: A commercially available array of light emitting diodes (LEDs), namely a UV Shark series LED high flux array, was evaluated as a light source for photolithographic patterning of SU-8 photoresist for the fabrication of templates suitable to make poly(dimethylsiloxane) (PDMS) microchips for electrophoresis. At a distance of 15cm from the substrate, a relatively even intensity of 0.76±0.05mW/cm2 was obtained over an area sufficient for patterning a 10cm (4in.) silicon wafer. The exposure source was evaluated using a spiral mask design covering a 10cm wafer. PDMS replicates of this template made in a 25μm thick layer of SU-8 3025 showed little variation in width over the surface of the substrate, with a variation of 3.2% RSD (n =36) and a maximum range in widths of 7.8% of the mean channel width. The use of the optional metal reflector available with the LED array provided partial collimation of the light allowing near vertical structures to be produced across the entire wafer, something which was not possible without the reflector. SU-8 masters prepared using the LED array were compared to masters made using an alternative cheap lithographic source, namely a gel crosslinker. The SU-8 features were much narrower with the LED array than the crosslinker due to the multiple light sources in the crosslinker. A PDMS microchip made using a SU-8 template created using the Shark UV LED array was used for the electrophoretic separation of three anionic fluorescent dyes, with efficiencies up to 32000 plates. Given that the LED array can be purchased and assembled for less than US$ 500, the Shark UV LED array is a promising alternative to more expensive lithographic light sources and will have significant appeal to many researchers wishing to undertake research in microfluidics around the world. [Copyright &y& Elsevier]

An electroosmotic flow (EOF) controlled counterflow isotachophoretic stacking boundary (cf-ITPSB) system under field amplified conditions has been examined as a way to improve the sensitivity of anions separated by capillary zone electrophoresis. The system comprised a high concentration of a high-mobility leading ion (100 mM chloride) and a low concentration of low-mobility terminating ion (1-3 mM MES or CHES) added to the sample in an unmodified fused-silica capillary at pH 8.05, buffered with Tris. Computer simulation studies using the software GENTRANS showed an increase in sensitivity of at least 10-fold over the previous cf-ITPSB system for simple inorganic ions, nitrite and nitrate. The simulations also suggested that the cf-ITPSB became stationary within the capillary and that its stationary position was not adversely affected by the concentration of MES. This was in contrast to experimental results that showed a slow and continual movement of the cf-ITPSB. This was more pronounced at lower concentrations of terminator (i.e., <3 mM) and resulted in a loss of resolution due to the cf-ITPSB being closer to the detector upon separation. This discrepancy was attributed to the change in pH across the capillary due to electrolysis and low buffering capacity in the sample, a phenomenon that cannot be simulated by the GENTRANS software. Replacement of MES with CHES as a lower mobility ion with increased buffer capacity failed to reduce the movement of the cf-ITPSB but did provide a further 3-fold improvement in sensitivity. The potential of this approach for sensitivity enhancement was demonstrated for the co-EOF separation of a mixture of six inorganic and small organic ions, with detection limits at the single-figure nanogram per liter level. These detection limits are 100 000 times better than can be achieved by normal hydrodynamic injection (ions prepared in water) and 250 times better than has been achieved by other online preconcentration approaches. The application of the EOF-controlled cf-1TPSB with counter-EOF separation of two pharmaceutical pollutants, naproxen and diflunisal, was also demonstrated with an improvement in sensitivity of 1000 giving detection limits of 350 ng/L in sewage treatment wastewater without any offline pretreatment. [ABSTRACT FROM AUTHOR]

Abstract: The development of new sensitive methods for the analysis of non-steroidal anti-inflammatory drugs (NSAIDs) in water samples is of great importance. In this work, seven NSAIDs were separated within 9min using 15mM sodium tetraborate (pH 9.2) containing 0.1% (w/v) hexadimethrine bromide (HDMB) and 10% (v/v) methanol. Field-amplified sample injection (FASI) was examined and found to improve the detection limits by 200-fold providing detection limits of 0.6–2.0μg/L, but these are insufficient for the determination of NSAIDs as environmental pollutants in water samples. To improve the sensitivity further, electrokinetic supercharging (EKS) was examined. The optimum EKS method involved hydrodynamic injection leading electrolyte (100mM NaCl, 30s, 50mbar), electrokinetic injection of the sample (200s, −10kV) and finally injection of the terminating electrolyte (100mM 2-(cyclohexylamino) ethanesulphonic acid, CHES, 40s, 50mbar). With this method, the sensitivity was improved by 2400-fold giving detection limits of 50–180ng/L. The developed method was validated and then applied to the analysis of wastewater samples from a local sewage treatment plant. The detection limits were found to increase by approximately 10-fold, however, this is still lower than levels previously found in wastewater samples from European and Mediterranean cities. The proposed method has the advantage of simplicity and achieving sensitivity through high-preconcentration power without the use of off-line chromatographic sample cleanup. [Copyright &y& Elsevier]

Abstract: A novel approach for in-line solid-phase extraction capillary electrophoresis (SPE-CE) for basic analytes was developed. The method is based on the use of a weak cation-exchange monolith synthesised in situ in the front end of the CE capillary via photoinitiated polymerization to form poly(methacrylic acid-co-ethylene glycol dimethacrylate), which was used to create the SPE phase in-line with the CE separation capillary. The monolithic SPE material exhibited a surface area of 23.1m2/g and a capacity of 403nM for dopamine. Adsorption of the analytes as protonated, cationic species onto the SPE phase was achieved using an electrolyte of 6mM phosphate and 12mM sodium ion, buffered at pH 7.0, which is above the pK a of the monolith but below the pK a of the analytes. Elution of the analytes from the SPE phase was achieved using an electrolyte with a pH below that of the pK a of the monolith, namely 12mM phosphate and 12mM sodium ion, buffered at pH 3.0. Due to the discontinuous electrolyte combination, analytes were simultaneously eluted and focused as the electrophoretically mobilised pH step boundary moved through the SPE monolith, after which the analytes were separated by conventional CZE in the remainder of the capillary. Quantitative extraction from a solution of 0.5μg/ml dopamine and epinephrine was achieved when flushing up to 15 column volumes of sample through the capillary. The limits of detection (S/N =3) for dopamine and epinephrine were 3.7 and 4.3ng/ml, and this method provided a sensitivity enhancement for dopamine of 462 times compared to CZE using hydrodynamic injection. The developed method was used to preconcentrate a test mixture of neurotransmitters comprising dopamine, epinephrine, 5-hydroxytryptamine, metanephrine and also histamine. The applicability of this approach to real life samples was demonstrated by using a urine sample from a healthy person to detect dopamine at sub-ppm levels. [Copyright &y& Elsevier]

Abstract: Non-aqueous capillary electrophoresis was evaluated for the separation of five hydrophobic basic blue dyes for application in forensic dye analysis. The use of a red light emitting diode as a high intensity, low-noise light source provided sensitive detection of the blue dyes while also allowing the evaluation of solvents that absorb strongly in the UV region. Excellent peak shapes and separation selectivity were obtained in methanol, ethanol, acetonitrile and dimethylsulfoxide, however water, tetrahydrofuran, dimethylformamide and acetone were unsuitable as solvents due to poor peak shapes and a lack of sensitivity, most likely due to adsorption onto the capillary wall. Due to the known compatibility of methanol with capillary electrophoresis–mass spectrometry, this solvent was examined further with the relative acidity/basicity of the electrolyte being optimised with an artificial neural network. The optimised method was examined for the separation of ink samples from 6 fibre tip and 2 ball point blue or black pens and showed that a unique migration time for the main dye component in seven of the eight pens could be obtained. [Copyright &y& Elsevier]

Abstract: A new frontal electroelution approach that can be used for the preconcentration of amino acids in in-line solid-phase extraction–capillary electrophoresis (SPE–CE) has been developed. A single capillary was employed featuring a short monolithic SPE column created inside the capillary via photo-initiated, free-radical polymerisation of 3-sulfopropyl methacrylate and butyl methacrylate monomers. A weak electrolyte of dilute H2SO4, pH 2.9, was found to promote adsorption of the amino acids onto the SPE column. Elution of the amino acids was achieved using a dual solvation/ion-exchange transient boundary mobilised via EOF by using a strong electrolyte containing 62.5mM ethylenediamine, pH 2.9 with H2SO4 and 40% (v/v) acetonitrile. Using these two electrolytes, tryptophan was adsorbed onto the SPE column in weak electrolyte and eluted via a frontal electroelution mechanism in the strong electrolyte. Injections up to 20min, corresponding to over 14 column volumes (or 1400% of the capillary volume) of sample provided quantitative extraction of tryptophan from the weak electrolyte and were eluted without any loss in efficiency. This represents a practical increase of approximately 300-fold when compared to a typical hydrodynamic injection occupying 5% of the capillary volume. [Copyright &y& Elsevier]

The dynamics of focusing weak bases using a transient pH boundary was examined via high-resolution computer simulation software. Emphasis was placed on the mechanism and impact that the presence of salt, namely, NaCl, has on the ability to focus weak bases. A series of weak bases with mobilities ranging from 5 × 10-9 to 30 × 10-9 m²/V·s and pKa values between 3.0 and 7.5 were examined using a combination of 65.6 mM formic acid, pH 2.85, for the separation electrolyte, and 65.6 mM formic acid, pH 8.60, for the sample matrix. Simulation data show that it is possible to focus weak bases with a pKa value similar to that of the separation electrolyte, but it is restricted to weak bases having an electrophoretic mobility of 20 × 10-9 m²/V·s or quicker. This mobility range can be extended by the addition of NaCl, with 50 mM NaCl allowing stacking of weak bases down to a mobility of 15 × 10-9 m²/V·s and 100 mM extending the range to 10 × 10-9 m²/V·s. The addition of NaCl does not adversely influence focusing of more mobile bases, but does prolong the existence of the transient pH boundary. This allows analytes to migrate extensively through the capillary as a single focused band around the transient pH boundary until the boundary is dissipated. This reduces the length of capillary that is available for separation and, in extreme cases, causes multiple analytes to be detected as a single highly efficient peak. [ABSTRACT FROM AUTHOR]

Abstract: Silica aerogels were prepared via the sol–gel process using tetramethoxysilane (TMOS) as the precursor and polyethylene oxide (PEO) of molecular weights 10,000 and 100,000 to provide a polymeric template for gelation. The experiments included eleven different formulations ranging from 100% 10,000MW PEO to 100% 100,000MW PEO in 10% increments. The total concentration of PEO was kept constant throughout the experiment. The gelation time of the wet-gel prepared using 10,000 MW PEO was 15.3 (±0.1)×103 s, while gelation occurred almost 30 times faster by using long-chain 100,000MW PEO. The surface area of aerogels prepared with 10,000MW PEO was 40m2 g−1 and that of 100,000MW PEO aerogels was more than an order of magnitude larger. The Young’s modulus of 10,000MW PEO aerogels was 1.2 (±0.3)MPa while that for 100,000MW PEO aerogels was almost four times larger. Estimated pore sizes for all types of gels were in the macroporous region. The estimated pore sizes for 10,000MW PEO were an order of magnitude greater than those estimated for 100,000MW PEO. The physical properties of silica aerogels such as gelation time, pore size, surface area, and Young’s modulus can be tailored to make them suitable for application as separation media in HPLC and CEC. [Copyright &y& Elsevier]

The electrokinetic separation of the hydrophobic antimycotic drug itraconazole (ITC) and its major metabolite, hydroxyitraconazole (HITC), by a binary aqueous–organic solvent medium containing sodium dodecylsulfate, by microemulsion electrokinetic chromatography (MEEKC) and by micellar electrokinetic chromatography (MEKC) was studied. The results suggest that the first approach is difficult to apply and that there is no substantial difference between separations performed using MEEKC and MEKC modified with n-butanol. The simpler MEKC method is more than adequate and was thus employed for the analysis of ITC and HITC in human serum and plasma. Separation was achieved in plain fused-silica capillaries having a low-pH buffer (pH 2.2) with sodium dodecyl sulfate micelles and reversed polarity. The addition of 2-propanol and n-butanol enhanced analyte solubility and altered the selectivity of the separation by influencing the magnitude of the electrophoretic component in the separation mechanism. Under optimised conditions and using head-column field-amplified sample stacking, an internal standard, ITC and two forms of HITC could be separated in under 9 min, with detection limits less than 0.01 μg/mL. Analysis of samples from patients currently prescribed ITC revealed a different HITC peak area ratio to that of the standards, suggesting a stereoselective component of ITC metabolisation. Comparison of MEKC data with those of a HPLC method employed on a routine basis showed excellent agreement, indicating the potential of this approach for therapeutic drug monitoring of ITC. [Copyright &y& Elsevier]

Demonstrates a microchip solid-phase extraction method for purification of DNA from biological samples. Optimization of load pH and flow rate; Purification of bacterial; Electropherograms of polymerase chain reaction product microchip separations after amplification of beta-globin gene in human genomic DNA.

Describes the optimization and utilization of a novel buffer system for fast DNA separations by capillary and microchip electrophoresis. Elimination of the need for surface preconditioning procedures; Promotion of hydrogen bonding of hydroxypropyl cellulose; Utility of the artificial neural network-optimized system for molecular diagnostic.

Examines the on-column ion-exchange preconcentration of inorganic anions with open tubular capillary electrophoresis and elution. Mechanisms of ion-exchange retention; Adsorption of cationic polymer; Optimization of electrolyte concentrations.

One of the problems with capillary electrophoresis is a lack of versatility regarding manipulation of the separation selectivity. A new and potentially universal concept is to introduce an ion-exchange component into a separation so that the migration of analyte ions is influenced by both their electrophoretic mobilities and their chromatographic properties. This may be accomplished by use of capillaries filled with or coated with solid ion-exchange polymers, or by addition of a soluble ionic polymer to the background electrolyte to create a pseudo-stationary phase. While each of these methods achieves the same result, they are not competitive, but rather complementary as the problems associated by one approach are overcome by the others. Recent highlights in the field are used to illustrate the flexibility that this approach provides to electrophoretic separation of ions. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

On-site therapeutic drug monitoring (TDM) is important for providing a quick and accurate dosing to patients in order to improve efficacy and minimize toxicity. Aminoglycosides such as amikacin, gentamicin, and tobramycin are important antibiotics that have been commonly used to treat infections of chronic bacterial infections in the urinary tract, lung, and heart. However, these aminoglycosides can lead to vestibular and auditory dysfunction. Therefore, TDM of aminoglycosides is important due to their ototoxicity and nephrotoxicity. Here, we have developed a hot embossed poly (methyl methacrylate) (PMMA) microfluidic device featuring an electrokinetic size and mobility trap (SMT) to purify, concentrate, and separate the aminoglycoside antibiotic drugs amikacin, gentamicin, and tobramycin. These drugs were separated successfully from whole blood within 3 min, with 30-fold lower detection limits compared to a standard pinched injection. The limit of detections (LOD) were 3.75 µg/mL for gentamicin, 8.53 µg/mL for amikacin, and 6.00 µg/mL for tobramycin. These are sufficient to cover the therapeutic range for treating sepsis of 6–10 μg/mL gentamicin and tobramycin and 12–20 μg/mL of amikacin. The device is simple and could be mass produced via embossing or injection molding approaches. [ABSTRACT FROM AUTHOR]

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. In this report, we present a novel isotachophoretic quantification method utilizing two nucleic acid stains, SYTO9 and propionic iodide, for the detection of total viable bacteria. The study employed E. coli M23 bacteria as a model organism, with an analysis time of only 30 min. The method demonstrated a limit of detection (LOD) of 184 CFU mL−1 and 14 cells mL−1 for total viable count and total cell count, respectively. Furthermore, this new approach is capable of detecting the microbial quality standard limits for food contacting surfaces (10 CFU cm−2) and meat (1.99 × 104 CFU cm−2) by swabbing an area of 10 × 10 cm2. In contrast to the culture-based methods usually employed in food processing facilities, this isotachophoretic technique enables easy and rapid detection (<30 min) of microorganisms, facilitating crucial decision-making essential for maintaining product quality and safety. [Display omitted] • This paper reports an ITP method to detect viable bacteria, with the potential to replace traditional plate count method. • The method identifies contaminated surfaces within 30 minutes, mitigating the risk of foodborne illness outbreaks. • The method can be adapted to various settings with modifications to detect total viable count. [ABSTRACT FROM AUTHOR]

The authors would like to call the reader’s attention to the following: The instrument they used to measure the volumetric precision of the dispensing devices is not called “VMS” but “PCS®”. [ABSTRACT FROM AUTHOR]

Magnetic particles (MPs) and magnetic nanoparticles (MNPs) are appealing candidates for biomedical and analytical applications due to their unique physical and chemical properties. Given that magnetic fields can be readily used to control the motion and properties of M(N)Ps, their integration in analytical methods opens new avenues for sensing and quantitative analysis. There is a large body of literature related to their synthesis, with a relatively small number of methods reporting the analysis of M(N)Ps using separation methods, which provide information on their purity and monodispersity. This review discusses analytical separation methods of M(N)Ps published between 2013 and June 2018. The analytical separation methods evaluated in this work include (i) field flow fractionation, (ii) capillary electrophoresis, (iii) macroscale magnetophoresis and (iv) microchip magnetophoresis. Among the trends in analytical separations of M(N)Ps an inclination towards miniaturization is moving from conventional benchtop methods to rapid and low-cost methods based on microfluidic devices. • The importance of analytical separations of magnetic (nano)particles is highlighted. • Analytical separations of magnetic (nano)particles during the period between 2013 and 2018 include field flow fractionation, macroscale magnetophoresis, capillary electrophoresis and microchip magnetophoresis. • Challenges and successes of different approaches on magnetic (nano)particle analytical separations are discussed and the future trends are explored. [ABSTRACT FROM AUTHOR]

Preconcentration is the aspect of analytical method development covering the need to improve detection sensitivity. This review collects the advances in a diversity of approaches to achieve preconcentration by solvent removal. Evaporation in microfluidic and paper-based devices is reported in a variety of forms and later compared to membrane-assisted evaporation. Sample partitioning in an immiscible fluid is also described. The reported methodologies highlight the need to achieve good control of the gas-liquid interface to obtain accurate results. A comprehensive comparison of different strategies is presented here discussing their benefits and drawbacks as well as the research needs in this area. Graphical abstract ᅟ [ABSTRACT FROM AUTHOR]

Front cover of the magazine "Angewandte Chemie" is presented.

An accurate and precise 3 μL blood collection and dispensing system is presented for the preparation of dried blood spot (DBS) samples. Using end-to-end glass capillaries in conjugation with pre-punched DBS pads, a blood micro collection system was developed to eliminate the haematocrit dispersion, widely associated with DBS technology, while providing better levels of accuracy and precision during sample preparation. This methodology is compared to traditional micro-volume blood collection systems, such as a pipette and a digitally controlled analytical syringe. Results showed that % of recovery for the capillary methodology was closer to 100% across the three haematocrit (HCT) levels tested and when prepared by two users (98 to 100% for capillaries, 78 to 104% for pipette and 93 to 97% for digital syringe) attesting a higher accuracy. Additionally, by taking advantage of the capillary action mechanism to collect and dispense autonomously the desired volume of blood onto the DBS pad, coefficients of variation between two individuals were significantly lower than with standard methodologies (capillaries—0.05 to 0.77%, pipette—12.71 to 18.53% and digital syringe—0.72 to 1.77%). This alternate aspiration and dispensing methodology could be used by different users without compromising accuracy or precision when handling low volumes of blood during the pre-analytical steps.Comparison of novel capillary dispensing methodology for dried blood spot sample preparation with pipette and digital syringe methodologies through accuracy and precision measurements of caffeine [ABSTRACT FROM AUTHOR]

Described as intrinsically powerful building blocks for two-dimensional separations by Giddings [Anal. Chem., 56 (1984) 1258A–1270A], the coupling of chromatography and electrophoresis has been proven to enhance the resolution of a wide array of molecules in complex biological, environmental and food samples. This review provides a comprehensive overview of multidimensional chromato-electrophoretic (LC - E) and electrophero-chromatographic (E - LC) separation systems from inception to the most recent published examples. LC separation modes include reversed phase, ion exchange, and size exclusion. Electromigration separation modes include capillary, microchip or free flow electrophoresis; micellar electrokinetic chromatography; electrochromatography; and isoelectric focusing. The advantages and disadvantages of various non-gel based off-line and on-line hyphenation technologies of LC - E and E - LC are discussed, with conditions and system characteristics also provided. [ABSTRACT FROM AUTHOR]

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. Herein, we developed a simple transient isotachophoretic (tITP)-CE method to detect MA and its precursor pseudoephedrine (PSE) in clan labs and non-invasive biological fluids. The method was implemented on the ETD-100, a commercial fully automated portable CE instrument with an integrated swab-based extraction system. Within 2 min of insertion of the swab, MA and PSE were automatically extracted with a leading electrolyte (LE) and then separated on covalently modified capillaries. The ETD-100 showed a limit of detection (LOD) and quantification (LOQ) of MA 0.02 and 0.05 μg/swab and 0.02 and 0.06 μg/swab of PSE, with an enhancement factor of 118 and 328, respectively, when compared to a normal non-tITP injection. The intra and inter-day relative standard deviation in terms of migration time were in the range of 0.75–1.93 % for both MA and PSE and were 2.0–2.4 % for both MA and PSE peak height. The method was demonstrated with the detection of spiked MA and PSE on different household materials as well as in non-invasive biological fluids with a recovery above 60 %. [Display omitted] • A tITP method was developed to detect Methamphetamine (MA) and pseudoephedrine (PSE). • A newly developed polymeric covalent coating was used to reduce electroosmotic flow. • The method was applied on a portable CE coupled with a swab-based sampler (ETD-100). • MA and PSE were detected on surfaces and non-invasive biological fluids using swabs. [ABSTRACT FROM AUTHOR]

Highlights: [•] Automated sequential injection capillary electrophoresis for bioprocess monitoring. [•] Determination of lactate in media with intraday electrophoretic mobility RSD 0.07%. [•] Requires only 1.99mL of sample for 228 analyses (every 20min over 3 days). [•] Special sampling interface for sampling of cell-free media from adherent cell cultures. [•] Provides a unique insight in changes in metabolism and cell health over time. [ABSTRACT FROM AUTHOR]

Abstract: Microfluidic chip electrophoresis (chip-CE) is a separation method that is compatible with portable and on-site analysis, however, only few commercial chip-CE systems with laser-induced fluorescence (LIF) and light emitting diode (LED) fluorescence detection are available. They are established for several application tailored methods limited to specific biopolymers (DNA, RNA and proteins), and correspondingly the range of their applications has been limited. In this work we address the lack of commercially available research-type flexible chip-CE platforms by exploring the limits of using an application-tailored system equipped with chips and methods designed for DNA separations as a generic chip-CE platform – this is a very significant issue that has not been widely studied. In the investigated Agilent Bioanalyzer chip-CE system, the fixed components are the Agilent chips and the detection (LIF at 635nm and LEDIF at 470nm), while the chemistry (electrolyte) and the programming of all the high voltages are flexible. Using standard DNA chips, we show that a generic CE function of the system is easily possible and we demonstrate an extension of the applicability to non-aqueous CE (NACE). We studied the chip compatibility with organic solvents (i.e. MeOH, ACN, DMF and DMSO) and demonstrated the chip compatibility with DMSO as a non-volatile and non-hazardous solvent with satisfactory stability of migration times over 50h. The generic CE capability is illustrated with separations of fluorescent basic blue dyes methylene blue (MB), toluidine blue (TB), nile blue (NB) and brilliant cresyl blue (BC). Further, the effects of the composition of the background electrolyte (BGE) on the separation were studied, including the contents of water (0–30%) and buffer composition. In background electrolytes containing typically 80mmol/L ammonium acetate and 870mmol/L acetic acid in 100% DMSO baseline separation of the dyes were achieved in 40s. Linearity was documented in the range of 5–28μmol/L, 10–100μmol/L, 1.56–50nmol/L and 5–75nmol/L (r 2 values in the range 0.974–0.999), and limit of detection (LOD) values were 90nmol/L, 1μmol/L 1.4nmol/L, and 2nmol/L for MB, TB, NB and BC, respectively. [Copyright &y& Elsevier]

Abstract: Over the past two decades, capillary electrophoresis (CE) has been the subject of extensive development and progress in various DNA based sieving electrophoresis applications, namely Sanger sequencing, forensic short tandem repeat (STR) analysis, clinical genotype screening (SNP), and phylogenetic fingerprinting. Yet, this trend has not been emulated in the RNA field. This review will highlight the development and key analysis parameters of RNA electrophoresis by CE and provide possible explanations for the low research interest in this area. [Copyright &y& Elsevier]

Abstract: Flavonoids are bioactive compounds found in plants. Studies indicate consumption of food containing these compounds may reduce the incidences of cancer and cardiovascular diseases. In broccoli, the flavonoids are present at variable concentrations and so far have mainly been determined using high performance liquid chromatography (HPLC). This paper describes a rapid capillary electrophoresis method, involving large volume sample stacking (LVSS), suitable for the analysis of flavonoids in broccoli. Following acid hydrolysis, the two key flavonoids (kaempferol and quercetin) in a broccoli extract were concentrated on-line by LVSS prior to separation by capillary zone electrophoresis (CZE). Using an optimised method, the extract was injected for 50s into a 50μm (internal diameter)×85cm (total length) capillary followed by stacking/matrix removal at −5kV for 83s. The two analytes were then separated in less than 8min by CZE using a 10mM sodium borate buffer (pH 8.40) and a separation voltage of +30kV at 30°C. A linear relationship in the range 1–20ppm was observed for the method (r 2 =0.9991–0.9995) with detection limits of 0.9 and 0.6mg/kg of broccoli for kaempferol and quercetin, respectively. This method demonstrated good repeatability for the standard and extract with relative standard deviations of less than 5% for both peak area and migration time measured over five different days (n =5). The method was successfully applied to quantitatively determine kaempferol and quercetin contents in a commercial broccoli sample as 11.8 and 14.6mg/kg fresh weight, respectively. This result was validated by HPLC analysis and is within the ranges reported in the literature. [Copyright &y& Elsevier]

Abstract: Glucoraphanin, a glucosinolate, is found naturally in plants and is present in relatively high concentrations in broccoli. Glucosinolates have received much attention as studies have indicated that a diet rich in them may provide some protection from certain cancers. A micellar electrokinetic chromatography (MEKC) method using sodium cholate as the micellar phase has been developed to quantify for glucoraphanin in broccoli (seeds and florets) and Brussels sprouts. The glucoraphanin peak elutes just under 5min with a theoretical plate number of 380,000 per metre of capillary. The method is suitable for crude extracts of broccoli and Brussels sprouts. Glucoraphanin in broccoli seeds (1330mg/100g) broccoli florets (89mg/100g) and Brussels sprouts (3mg/100g) was determined and agreed with the data obtained by high performance liquid chromatography. The LODs were 10–100 times below the levels typically found in broccoli seeds (4mg/100g), broccoli florets (0.9mg/100g) and Brussels sprouts (0.1mg/100g). [Copyright &y& Elsevier]

Abstract: This study explores the use of pH stacking in conjunction with 5-aminofluorescein as a derivatization agent for the sensitive analysis of simple sugars such as glucose, lactose and maltotriose by capillary electrophoresis (CE). The derivatization agent was selected on the basis of its extremely high molar absorptivity, its compatibility with a 488nm light-emitting diode (LED) and the fact that it has two ionizable groups making it compatible with on-line stacking using a dynamic pH junction. The influence of both acetic and formic acids at concentrations of 0.19, 0.019 and 0.0019molL−1 were investigated with regard to both derivatization efficiency and the ability to stack using a dynamic pH junction. Superior sensitivity and resolution was obtained in formic acid over acetic acid. Substantially lower peaks were obtained with 0.19molL−1 formic acid when compared to 0.019 and 0.0019molL−1 concentrations, which was confirmed by computer simulation studies to be due to the inadequate movement of the pH boundary for stacking. Further simulation studies combined with experimental data showed the separation with the best resolution and greatest sensitivity when the carbohydrates were derivatized with the 0.095molL−1 formic acid. Utilisation of stacking via dynamic pH junction mode in conjunction with LED detection enabled efficiencies of 150,000 plates and detection limits in the order of 8.5×10−8 molL−1 for simple sugars such as glucose, lactose and maltotriose hydrate. The current system also demonstrates a 515 times improvement in sensitivity when compared to using a normal deuterium lamp, and 16 times improvement over other systems using LEDs. [Copyright &y& Elsevier]

High solids content complicates in situ analysis of chemical processing, biological suspensions, and environmental streams. In most cases, analytical methods require at least one pre‐treatment step of a small volume of sample before a particle‐free fluid can be analyzed. We have developed a continuous in situ sampler that can "sip" particle‐free solution from a turbulent high solids content stream (a slurry). An open microfluidic chip with an extended slit opening shields the internal laminar flow from the turbulence outside. Unlike other open chips, our chip does not require close proximity to a solid surface and operates in turbulent environments for hours without maintenance. Two applications are demonstrated: monitoring FeIII in a stirred slurry of mixed ore particles at high solids loading (4 %wt) and paracetamol tablet dissolution profiles for two different formulations. [ABSTRACT FROM AUTHOR]

Here, an electrokinetic extraction (EkE) syringe is presented allowing for on‐line electrokinetic removal of serum proteins before ESI‐MS. The proposed concept is demonstrated by the determination of pharmaceuticals from human serum within minutes, with sample preparation limited to a 5× dilution of the sample in the background electrolyte (BGE) and application of voltage, both of which can be performed in‐syringe. Signal enhancements of 3.6–32 fold relative to direct infusion of diluted serum and up to 10.8 fold enhancement, were obtained for basic and acidic pharmaceuticals, respectively. Linear correlations for the basic drugs by EkE‐ESI‐MS/MS were achieved, covering the necessary clinical range with LOQs of 5.3, 7.8, 6.1, and 17.8 ng mL−1 for clomipramine, chlorphenamine, pindolol, and atenolol, respectively. For the acidic drugs, the EkE‐ESI‐MS LOQs were 3.1 μg mL−1 and 2.9 μg mL−1 for naproxen and paracetamol, respectively. The EkE‐ESI‐MS and EkE‐ESI‐MS/MS methods showed good accuracy (%found of 81 % to 120 %), precision (≤20 %), and linearity (r>0.997) for all the studied drugs in spiked serum samples. [ABSTRACT FROM AUTHOR]