Cu-nanoparticles@ graphene nanocomposite: A robust and efficient nanocomposite for micro-solid phase extraction of trace aflatoxins in different foodstuffs.

Cu-nanoparticles-immobilized graphene (Cu@G) nanocomposite was fabricated in this study by reducing Cu(II) ions in the presence of graphene oxide using a simple chemical reduction step. Cu@G nanocomposite was applied as a sorbent for the SPE of four aflatoxins (AFs). A reusable syringe was filled with the fabricated nanocomposite and used as a sorbent for the micro-solid phase extraction of four AFs (AFB1, AFB2, AFG1, AFG2). The impact of different analytical factors was fully investigated and optimized. Excellent recoveries, ranging from 92.0 to 108.5 %, were detected when evaluating target AFs in samples of rice, maize, and pistachio. The LOD, LOQ, and linear ranges were attained under optimal circumstances in the ranges of 0.0062 µg kg-1, 0.0192 µg kg-1, and 0.0-20 µg kg-1, respectively. The discovered approach provided the dual benefits of a high enrichment capability of Cu-nanoparticles via AFs complexation and a huge porosity of graphene sheets.

Facile adsorption-electroflotation method for the removal of heavy metal ions from water using carbon nanomaterials.

Due to the none-biodegradable and carcinogenic nature of toxic metal ions, a novel sorption-electroflotation method was developed using carbon nanomaterials. The metal ions removed were Ni(II), Co(II), Zn(II), Fe(II), and Cu(II) using carbon nanotubes (CNTs) and carbon nanoshells (CNSs). The porous structure, morphology, composition, and surface properties of carbon nanomaterials, viz. the presence and number of functional groups are characterized by methods of low-temperature nitrogen adsorption, scanning electron microscopy, Boem, X-ray photoelectron spectroscopy. The surface of the materials was rough with varied particle sizes. Regardless of the sorbed ion and the nature of the nanomaterial, the Langmuir, Temkin, Dubinin-Radushkevich, and Flory-Higgins models were applied to the data. The maximum sorption removal on CNTs were 15.0-69.0, 36.0-75.0, 33.0-72.0, 18.0-70.0, 29.0-69.0% for Fe(II), Zn(II), Co(II), Cu(II), and Ni(II) while these values on CNSs were 19.0-53, 23.0-58.0, 30.0-79.0, 12.0-46.0, and 41.0-86%. But after simultaneous sorption-electroflotation, the percentage removal was 99.0, 97.0, 95.0, 99.0, and 52% for these metal ions, indicating an excellent combination of sorption-electro flotation. The method is highly beneficial to work in varied pH ranges as sorption and electroflotation gave the best results in acidic and basic mediums. The method is very effective, efficient, and inexpensive and can be used for the removal of the reported metal ions in water.

Seawater Splitting for Hydrogen Generation Using Zirconium and Its Niobium Alloy under Gamma Radiation.

Hydrogen production is produced for future green energy. The radiation-chemical yield for seawater without a catalyst, with Zr, and with Zr1%Nb (Zr = 99% Nb = 1%) were (G(H2) = 0.81, 307.1, and 437.4 molecules/100 eV, respectively. The radiation-thermal water decomposition increased in γ-radiation of the Zr1%Nb + SW system with increasing temperature. At T = 1273 K, it prevails over radiation processes. During the radiation and heat radiation heterogeneous procedures in the Zr1% Nb + SW system, the production of surface energetic sites and secondary electrons accelerated the accumulation of molecular hydrogen and Zr1%Nb oxidation. Thermal radiation and thermal processes caused the metal phase to collect thermal surface energetic sites for water breakdown and Zr 1%Nb oxidation starting at T = 573 K.

An Ionic-Liquid-Imprinted Nanocomposite Adsorbent: Simulation, Kinetics and Thermodynamic Studies of Triclosan Endocrine Disturbing Water Contaminant Removal.

The presence of triclosan in water is toxic to human beings, hazardous to the environment and creates side effects and problems because this is an endocrine-disturbing water pollutant. Therefore, there is a great need for the separation of this notorious water pollutant at an effective, economic and eco-friendly level. The interface sorption was achieved on synthesized ionic liquid-based nanocomposites. An N-methyl butyl imidazolium bromide ionic liquid copper oxide nanocomposite was prepared using green methods and characterized by using proper spectroscopic methods. The nanocomposite was used to remove triclosan in water with the best conditions of time 30 min, concentration 100 µg/L, pH 8.0, dose 1.0 g/L and temperature 25 °C, with 90.2 µg/g removal capacity. The results obeyed Langmuir, Temkin and D-Rs isotherms with a first-order kinetic and liquid-film-diffusion kinetic model. The positive entropy value was 0.47 kJ/mol K, while the negative value of enthalpy was -0.11 kJ/mol. The negative values of free energy were -53.18, -74.17 and -76.14 kJ/mol at 20, 25 and 30 °C. These values confirmed exothermic and spontaneous sorption of triclosan. The combined effects of 3D parameters were also discussed. The supramolecular model was developed by simulation and chemical studies and suggested electrovalent bonding between triclosan and N-methyl butyl imidazolium bromide ionic liquid. Finally, this method is assumed as valuable for the elimination of triclosan in water.

Polyaniline Modified CNTs and Graphene Nanocomposite for Removal of Lead and Zinc Metal Ions: Kinetics, Thermodynamics and Desorption Studies.

A novel polyaniline-modified CNT and graphene-based nanocomposite (2.32-7.34 nm) was prepared and characterized by spectroscopic methods. The specific surface area was 176 m2/g with 0.232 cm3/g as the specific pore volume. The nanocomposite was used to remove zinc and lead metal ions from water; showing a high removal capacity of 346 and 581 mg/g at pH 6.5. The data followed pseudo-second-order, intraparticle diffusion and Elovich models. Besides this, the experimental values obeyed Langmuir and Temkin isotherms. The results confirmed that the removal of lead and zinc ions occurred in a mixed mode, that is, diffusion absorption and ion exchange between the heterogeneous surface of the sorbent containing active adsorption centers and the solution containing metal ions. The enthalpy values were 149.9 and 158.6 J.mol-1K-1 for zinc and lead metal ions. The negative values of free energies were in the range of -4.97 to -26.3 kJ/mol. These values indicated an endothermic spontaneous removal of metal ions from water. The reported method is useful to remove the zinc and lead metal ions in any water body due to the high removal capacity of nanocomposite at natural pH of 6.5. Moreover, a low dose of 0.005 g per 30 mL made this method economical. Furthermore, a low contact time of 15 min made this method applicable to the removal of the reported metal ions from water in a short time. Briefly, the reported method is highly economical, nature-friendly and fast and can be used to remove the reported metal ions from any water resource.

Cyclodextrin-Modified Micellar UPLC for Direct, Sensitive and Selective Determination of Water Soluble Vitamins in Milk.

Cyclodextrin-modified micellar ultra pressure liquid chromatography (CD-MUPLC) was firstly developed and directly applied to the simultaneous determination of water-soluble vitamins thiamine hydrochloride (VB1), pyridoxine hydrochloride (VB6) and ascorbic acid (VC) in milk samples. A hybrid isocratic mobile phase consisting of ß-cyclodextrin (ß-CD, 5.0 mmol L-1) and cetyltrimethylammonium bromide (CTAB, 0.1 mol L-1) in the presence of acetic acid (0.1 mol L-1) at pH 2.9 on a RP-C18 column at 25.0°C was successfully used. The separation of vitamins was achieved in less than 10 min at a 0.2 mL min-1 flow rate showing adequate linearity at 245 nm in the ranges of 5.0-500.0 µg L-1 for VB1, 5.0-1000.0 µg L-1 for VB6 and 5.0-10000.0 µg L-1 for VC with coefficients of variation (r2) of 0.9999, 0.9987 and 0.9971, respectively. In addition, limits of detection obtained were 0.885, 1.352 and 1.358 µg L-1 and limits of quantification were 2.681, 4.096 and 4.115 µg L-1 for VB1, VB6 and VC, respectively. The high sensitivity of the proposed CD-MUPLC-UV method permitted its applications to the determination of water-soluble vitamins VB1 (32-488 µg L-1), VB6 (82-95 µg L-1) and VC (790-45000 µg L-1) in breast and bovine milk samples. The relative standard deviations and recoveries ranged between 0.07 and 2.14% and between 85.27 and 114.8%, respectively, indicating the accurate and precise measurements without any negative impact of matrix. The current analytical method illustrated several advantages including direct, sensitive, selective and non-consuming organic solvents over the hitherto published methods. These features could be attributed to the four-point competitive interactions among analytes, pseudostationary phases and modified C18 stationary phases.

Hyphenation of enzyme/graphene oxide-ionic liquid/glassy carbon biosensors with anodic differential pulse stripping voltammetry for reliable determination of choline and acetylcholine in human serum.

Acetylcholine (ACh) and its precursor choline (Ch) play important roles in many biological processes. It is expected that Alzheimer's disease is occurred due to the reduction in synthesis of ACh. On the other hand, the increase in the level of ACh results in a depression of heart rate and over production of saliva. Therefore, the quantitative determination of Ch and ACh is very important in biological media. In the current work, sensitive and selective biosensors composed of choline oxidase (ChO) and/or acetylcholine esterase (AChE) on graphene oxide-ionic liquid (GO-IL)/ glassy carbon electrode (GCE) hyphenated with anodic differential pulse stripping voltammetry (ADPSV) were firstly established for the determination of ACh and Ch in human serum samples. The molecular bond of ionic liquid 1-allyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (AMIM TFSI) with GO was investigated by FT-IR and UV-Vis techniques. Furthermore, the surface topography of ChO/GO-IL and AChE-ChO/GO-IL composites was investigated by SEM and XRD. Then, the electron transfer features of biosensors ChO/GO-IL/GCE and AChE-ChO/GO-IL/GCE were characterized by the electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The ADPSV was further used for the determination of Ch and ACh. The experimental parameters such as differential pulse working potential, differential pulse scan rate, equilibrium time and long-term stability were further optimized. Detection limits of 0.885 and 1.352 nmol L-1 with excellent linearity (R2 = 0.9996) over the range of 5-1000 nmol L-1 were obtained for Ch and ACh, respectively. The developed analytical methods showed excellent accuracy and precision for the determination of Ch and ACh in human serum samples avoiding their pretreatment or purification.

Temperature controlled ionic liquid aqueous two phase system combined with affinity capillary electrophoresis for rapid and precise pharmaceutical-protein binding measurements.

Temperature controlled ionic liquid aqueous two phase system (ILATPS) was used to improve the precision of pharmaceutical-AGP (human alpha (α1)-acid glycoprotein) binding measurements by affinity capillary electrophoresis (ACE). The effect of different types of short-chain alkyl imidazolium ILs within the concentration range of 10.0-1000.0 µmol L-1 on a propranolol (PRO)-AGP model was firstly investigated by ILATPS/ACE system. Use of 100.0 µmol L-1 1-butyl-3-methylimidazolium chloride (BMImCl) in 67.0 mmol L-1 potassium phosphate buffer (pH 7.4) containing low concentrations of AGP (5.0-100.0 µmol L-1) gave the highest precision value (2.98 ±â€¯0.14 × 105 L/mol) which is in concord with the reported one (3.00 × 105) under similar experimental conditions. The proposed BMImCl/phosphate solution was a unique temperature controlled system to preserve AGP activity during the pre-analysis and within ACE measurements under lab conditions for about 30 days. This period could be prolonged by converting the one-phase solution into biphasic solution at 4 °C storage temperature and again it could get rapidly back into one-phase by raising the temperature with gentle shaking. This behavior could be attributed to the electrostatic interaction and π-π interaction between BMIm cations and negatively charged AGP ions (pI = 2.7). Moreover, the compatibility of ILATPS with ACE has been the critical factor to avoid precipitation of salts formed by anion exchange in the running buffer. The current ILATPS/ACE system was further used to rapidly and precisely estimate the binding constants of anticancer drugs methotrexate (MTX) and vinblastine (VBL) with human AGP. The obtained binding values have been in good agreements with their findings by high performance affinity chromatography (HPAC). This ILATP/ACE system could similarly be applied to improve the precision of other proteins binding measurements with consuming a small amount of protein and with shortening ACE analysis time.

Ultrasound-assisted temperature-controlled ionic liquid dispersive liquid-phase microextraction combined with reversed-phase liquid chromatography for determination of organophosphorus pesticides in water samples.

A rapid and sensitive ultrasound-assisted temperature-controlled ionic liquid (IL) dispersive liquid-phase microextraction (UTILDLPME) combined with reversed-phase liquid chromatography-ultraviolet (RPLC-UV) was developed for the determination of five organophosphorus pesticides (OPPs; azinphos-methyl, chloropyriphos, parathion-methyl, diazinon, and phosalone) in water samples. Parameters including IL type, IL volume, ionic strength, sonication time, heating/cooling temperature, centrifugal time, and speed were investigated. The extraction procedure was induced by the formation of cloudy solution, which was composed of 75 µL of 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM]PF6 ) dispersed entirely into 5 mL sample solution with the assistance of ultrasound for 3 min and temperature at 40°C. Under optimal conditions, linearity of the five OPPs was obtained in the range of 0.09-200 ng/mL with correlation coefficients of 0.998 or more. Limits of detection and limits of quantitation ranged from 0.01 to 0.1 ng/mL and from 0.05 to 0.4 ng/mL, respectively. Compared with conventional microextraction techniques, the proposed UTILDLPME exhibited the highest extraction efficiency ranging between 90 and 98% for targeted OPPs. Furthermore, the proposed UTILDLPME/RPLC was successfully applied to different water samples (tap, well, and lake water) showing relative recoveries ranging from 96.9 to 103.2%. Therefore, UTILDLPME/RPLC-UV could be a simple, rapid, sensitive, and efficient routine technique for determination of OPPs in water.

Ionic liquids in enhancing the sensitivity of capillary electrophoresis: Off-line and on-line sample preconcentration techniques.

The popularity of ionic liquids (ILs) has grown during the last decade in enhancing the sensitivity of CE through different off-line or on-line sample preconcentration techniques. Water-insoluble ILs were commonly used in IL-based liquid phase microextraction, in all its variants, as off-line sample preconcentration techniques combined with CE. Water-soluble ILs were rarely used in IL-based aqueous two phase system (IL-ATPS) as an off-line sample preconcentration approach combined with CE in spite of IL-ATPS predicted features such as more compatibility with CE sample injection due to its relatively low viscosity and more compatibility with CE running buffers avoid, in some cases, anion exchange precipitation. Therefore, the attentions for the key parameters affecting the performance of IL-ATPSs were generally presented and discussed. On-line CE preconcentration techniques containing IL-based surfactants at nonmicellar or micellar concentrations have become another interesting area to improve CE sensitivity and it is likely to remain a focus of the field in the endeavor because of their numerous to create rapid, simple and sensitive systems. In this article, significant contributions of ILs in enhancing the sensitivity of CE are described, and a specific overview of the relevant examples of their applications is also given.

Stabilizing proteins for affinity capillary electrophoresis using ionic liquid aqueous two phase systems: Pharmaceuticals and human serum albumin.

Recently, ionic liquids (ILs) are finding ever broader scope within pharmaceutical and bioanalytical applications. In the current work, ACE binding measurements of tryptophan (Try)-HSA, chlorambucil (CHL)-HSA, and dacarbazine (DTIC)-HSA complexes were estimated in the absence or presence of several short chain imidazolium ILs within the range of concentrations of 10.0-1000.0 µmol/L that are far below the critical micelle concentrations of ILs. Results indicated that the value of binding constant of Trp-HSA was dramatically deviated in the presence of 1000.0 µmol/L 1-decyl-3-methylimidazolium bromide (DMIMBr) IL. However, interestingly, there is no any deviation for the Trp-HSA binding constant with 100.0 µmol/L 1-butyl-3-methylimidazolium bromide (BMIMBr) IL as an adjuvant additive in 67.0 mmol/L phosphate buffer at pH 7.4. This finding was further used to estimate the binding constants of important but weakly binding substances of CHL and DTIC antitumors with HSA; their binding constants were also estimated by HPAC giving data in good agreement with that revealed by ACE. These achievements were attributed to the significant improvement of HSA stability by combination with BMIMBr IL through hydrogen bond, electrostatic, and π-π forces. In addition, the use of 100.0 µmol/L BMIMBr extended the stability of native HSA solution stored under the ambient lab conditions up to 25 days with significant improvements in the precision of ACE binding data.

Optimization of affinity capillary electrophoresis for routine investigations of protein-metal ion interactions.

To facilitate the implementation of affinity capillary electrophoresis into routine binding screening studies of proteins with metal ions, method acceleration, transfer and precision improvement were investigated. Affinity capillary electrophoresis was accelerated by using shorter capillaries, employing lower sample concentrations and smaller injection volumes. Intra- and inter-instrument method transfers were investigated considering the temperature setting of the capillary cooling system. For intra-instrument method transfer, similar results were obtained when transferring a method from a long (62 cm) to a short (31 cm) capillary. The analysis time was reduced from 9 to 4 min. In case of inter-instrument method transfer, interaction results showed small variation on the capillary electrophoresis instrument with inefficient capillary cooling system. Binding measurement precision was enhanced by slightly pushing the sample above the beginning of the capillary. Changing the buffer vials after each 30 runs and employing extra flushing after each 60 subsequent runs further enhanced the precision. The use of 0.1 molar ethylenediaminetetraacetic acid in the rinsing solution successfully desorbs the remaining metal ions from the capillary wall. Excellent precision for apparent mobility ratio measurements was achieved for different protein-metal ion interactions (relative standard deviation of 0.16-0.89%, 15 series, 12 runs for each).

Simultaneous determination of acrylamide, asparagine and glucose in food using short chain methyl imidazolium ionic liquid based ultrasonic assisted extraction coupled with analyte focusing by ionic liquid micelle collapse capillary electrophoresis.

Acrylamide (AA) is a known lethal neurotoxin and carcinogen. AA is formed in foods during the browning process by the Maillard reaction of glucose (GL) with asparagine (AS). For the first time, the simultaneous online preconcentration and separation of AA, AS and GL using analyte focusing by ionic liquid micelle collapse capillary electrophoresis (AFILMC) was presented. Samples were prepared in a 1-butyl-3-methylimidazolium bromide (BMIMBr) micellar matrix with a conductivity 4 times greater than that of the running buffer (12.5 mmol L(-1) phosphate buffer at pH 8.5). Samples were hydrodynamically injected into a fused silica capillary at 25.0 mbar for 25.0 s. Separations were performed by applying a voltage of 25.0 kV and a detection at 200.0 nm. To sufficiently reduce BMIMBr adsorption on the interior surface of capillary, an appropriate rinsing procedure by hydrochloric acid and water was optimized. AFILMC measurements of analytes within the concentration range of 0.05-10.0 µmol L(-1) achieved adequate reproducibility and accuracy with RSD 1.14-3.42% (n=15) and recovery 98.0-110.0%, respectively. Limits of detections were 0.71 ng g(-1) AA, 1.06 ng g(-1) AS and 27.02 ng g(-1) GL with linearity ranged between 2.2 and 1800 ng g(-1). The coupling of AFILMC with IL based ultrasonic assisted extraction (ILUAE) was successfully applied to the efficient extraction and determination of AA, AS and GL in bread samples. The structure of ILs has significant effects on the extraction efficiency of analytes. The optimal extraction efficiency (97.8%) was achieved by an aqueous extraction with 4:14 ratio of sample: 3.0 mol L(-1) BMIMBr followed by sonication at 35 °C. The proposed combination of ILUAE and AFILMC was simple, ecofriendly, reliable and inexpensive to analyze a toxic compound and its precursors in bread which is applicable to food safety.

Data quality in drug discovery: the role of analytical performance in ligand binding assays.

Despite its importance and all the considerable efforts made, the progress in drug discovery is limited. One main reason for this is the partly questionable data quality. Models relating biological activity and structures and in silico predictions rely on precisely and accurately measured binding data. However, these data vary so strongly, such that only variations by orders of magnitude are considered as unreliable. This can certainly be improved considering the high analytical performance in pharmaceutical quality control. Thus the principles, properties and performances of biochemical and cell-based assays are revisited and evaluated. In the part of biochemical assays immunoassays, fluorescence assays, surface plasmon resonance, isothermal calorimetry, nuclear magnetic resonance and affinity capillary electrophoresis are discussed in details, in addition radiation-based ligand binding assays, mass spectrometry, atomic force microscopy and microscale thermophoresis are briefly evaluated. In addition, general sources of error, such as solvent, dilution, sample pretreatment and the quality of reagents and reference materials are discussed. Biochemical assays can be optimized to provide good accuracy and precision (e.g. percental relative standard deviation <10 %). Cell-based assays are often considered superior related to the biological significance, however, typically they cannot still be considered as really quantitative, in particular when results are compared over longer periods of time or between laboratories. A very careful choice of assays is therefore recommended. Strategies to further optimize assays are outlined, considering the evaluation and the decrease of the relevant error sources. Analytical performance and data quality are still advancing and will further advance the progress in drug development.

A comprehensive platform to investigate protein-metal ion interactions by affinity capillary electrophoresis.

In this work, the behavior of several metal ions with different globular proteins was investigated by affinity capillary electrophoresis. Screening was conducted by applying a proper rinsing protocol developed by our group. The use of 0.1M EDTA in the rinsing solution successfully desorbs metal ions from the capillary wall. The mobility ratio was used to evaluate the precision of the method. Excellent precision for repeated runs was achieved for different protein metal ion interactions (RSD% of 0.05-1.0%). Run times were less than 6 min for all of the investigated interactions. The method has been successfully applied for the interaction study of Li(+), Na(+), Mg(2+), Ca(2+), Ba(2+), Al(3+), Ga(3+), La(3+), Pd(2+), Ir(3+), Ru(3+), Rh(3+), Pt(2+), Pt(4+), Os(3+), Au(3+), Au(+), Ag(+), Cu(1+), Cu(2+), Fe(2+), Fe(3+), Co(2+), Ni(2+), Cr(3+), V(3+), MoO4(2-) and SeO3(2-) with bovine serum albumin, ovalbumin, ß-lactoglobulin and myoglobin. Different interaction values were obtained for most of the tested metal ions even for that in the same metal group. Results were discussed and compared in view of metal and semimetal group's interaction behavior with the tested proteins. The calculated normalized difference of mobility ratios for each protein-metal ion interaction and its sign (positive and negative) has been successfully used to detect the interaction and estimate further coordination of the bound metal ion, respectively. The comprehensive platform summarizes all the obtained interaction results, and is valuable for any future protein-metal ion investigation.

Eco-friendly ionic liquid assisted capillary electrophoresis and α-acid glycoprotein-assisted liquid chromatography for simultaneous determination of anticancer drugs in human fluids.

In the current work, two eco-friendly analytical methods based on capillary electrophoresis (CE) and reversed phase liquid chromatography (RPLC) were developed for simultaneous determination of the most commonly used anticancer drugs for Hodgkin's disease: methotrexate (MTX), vinblastine, chlorambucil and dacarbazine. A background electrolyte (BGE) of 12.5 mmol/L phosphate buffer at pH 7.4 and 0.1 µmol/L 1-butyl-3-methyl imidazolium bromide (BMImBr) ionic liquid (IL) was used for CE measurements at 250 nm detection wavelength, 20 kV applied voltage and 25 °C. The rinsing protocol was significantly improved to reduce the adsorption of IL on the interior surface of capillary. Moreover, RPLC method was developed on α-1-acid glycoprotein (AGP) column. Mobile phase was 10 mmol/L phosphate buffer at pH 6.0 (100% v/v) and flow rate at 0.1 mL/min. As AGP is a chiral column, it was successfully separated l-MTX from its enantiomer impurity d-MTX. Good linearity of quantitative analysis was achieved with coefficients of determinations (r(2) ) >0.995. The stability of drugs measurements was investigated with adequate recoveries up to 24 h storage time under ambient temperature. The limits of detection were <50 and 90 ng/mL by CE and RPLC, respectively. The using of short-chain IL as an additive in BGE achieved 600-fold sensitivity enhancement compared with conventional Capillary Zone Electrophoresis (CZE). Therefore, for the first time, the proposed methods were successfully applied to determine simultaneously the analytes in human plasma and urine samples at clinically relevant concentrations with fast and simple pretreatments. Developed IL-assisted CE and RPLC methods were also applied to measure MTX levels in patients' samples over time.

Cyclodextrin Micellar LC for Direct Selective Analysis of Combined Dosage Drugs in Urine.

Two cyclodextrin micellar liquid chromatographic methods were developed and applied to the simultaneous determination of bisoprolol/hydrochlorothiazide and atenolol/chlorthalidone combinations in urine matrices without sample pretreatment. These combined ß-blockers and diuretics chemotherapies are commonly used in the treatment of hypertension and cardiovascular diseases. Hybrid isocratic mobile phases containing hydroxypropyl-ß-cyclodextrin, sodium dodecyl sulfate, phosphate buffer and methanol on a Luna C18 column with 0.5 mL min(-1) flow rate and 25.0°C column temperature were used. The methods were sensitive enough for the determination of analytes at the therapeutic urine levels with limits of detections down to 1.0 µg mL(-1); relative standard deviations and recoveries were ranged between 1.5-4.4% and 98.00-109.52%, respectively. Urinary excretion studies showed that the detection of drugs is possible up to 24 h after their ingestion. The selective proposed separations with less consumption of organic solvents over the hitherto ones could be attributed to the four point competitive interactions among analysts, pseudostationary phases and a real stationary phase.

Recent advances in affinity capillary electrophoresis for binding studies.

The present review covers recent advances and important applications of affinity capillary electrophoresis (ACE). It provides an overview about various ACE types, including ACE-MS, the multiple injection mode, the use of microchips and field-amplified sample injection-ACE. The most common scenarios of the studied affinity interactions are protein-drug, protein-metal ion, protein-protein, protein-DNA, protein-carbohydrate, carbohydrate-drug, peptide-peptide, DNA-drug and antigen-antibody. Approaches for the improvements of ACE in term of precision, rinsing protocols and sensitivity are discussed. The combined use of computer simulation programs to support data evaluation is presented. In conclusion, the performance of ACE is compared with other techniques such as equilibrium dialysis, parallel artificial membrane permeability assay, high-performance affinity chromatography as well as surface plasmon resonance, ultraviolet, circular dichroism, nuclear magnetic resonance, Fourier transform infrared, fluorescence, MS and isothermal titration calorimetry.

Synthesis-microstructure-performance relationship of layered transition metal oxides as cathode for rechargeable sodium batteries prepared by high-temperature calcination.

Research on sodium batteries has made a comeback because of concern regarding the limited resources and cost of lithium for Li-ion batteries. From the standpoint of electrochemistry and economics, Mn- or Fe-based layered transition metal oxides should be the most suitable cathode candidates for affordable sodium batteries. Herein, this paper reports a novel cathode material, layered Na1+x(Fey/2Niy/2Mn1-y)1-xO2 (x = 0.1-0.5), synthesized through a facile coprecipitation process combined with subsequent calcination. For such cathode material calcined at 800 °C for 20 h, the Na/Na1+x(Fey/2Niy/2Mn1-y)1-xO2 (x = 0.4) electrode exhibited a good capacity of 99.1 mAh g(-1) (cycled at 1.5-4.0 V) and capacity retention over 87% after 50 cycles. Optimization of this material would make layered transition metal oxides a strong candidate for the Na-ion battery cathode.

Alkyl imidazolium ionic liquid based sweeping-micellar electrokinetic chromatography for simultaneous determination of seven tea catechins in human plasma.

Determination of tea catechins in human plasma might provide a means of better evaluation of their benefits. The main difficulty in their analysis is the low catechins concentrations in plasma and their susceptible to oxidation during sample pretreatment. In the current work, a sweeping-micellar electrokinetic chromatography (sweeping-MEKC) by long alkyl chain ionic liquid was investigated for the simultaneous determination of seven principal naturally-occurring tea catechins in human plasma under acidic conditions after the intake of green tea beverage. The effects of type and concentration of three 1-tetradecyl-3-methylimidazolium ionic liquids, namely bromide, acetate and hydrogen sulfate salts were studied. The seven catechins were successfully separated within 5min by micellar running buffer of 5mmolL(-1) 1-tetradecyl-3-methylimidazolium bromide and 15mmolL(-1) phosphate buffer at pH 4.5 under optimal parameters of 50mbar injection for 150s, 10kV, 25°C and 200nm. To prevent the possibility of IL adsorption, an appropriate rinsing protocol was established. The method has analytical ranges from 0.5, 1, 0.5, 1, 2, 1 and 1 to 500ngmL(-1) for GC, C, EC, EGCG, GCG, ECG and EGC, respectively (r ranged from 0.995 to 0.999). The intraday precision and accuracy were 0.1-0.9% RSD (n=10) and 97-106% recovery, respectively. Limits of detections of analytes were ranged from 0.2 to 1.2ngmL(-1). The current sweeping-MEKC achieved sensitivity enhancement factor (SEF) up to 183-fold of analytes concentrations compared to other hitherto published CE reports that is suitable to find out the trace amounts of catechins in plasma.