Imidazolium-based ionic liquid derivative/Cu<Superscript>II</Superscript> complexes as efficient catalysts of the lucigenin chemiluminescence system and its application to H<Subscript>2</Subscript>O<Subscript>2</Subscript> and glucose detection

The effects of six synthetic imidazolium-based ionic liquids (ILs) on the Cu^II-catalyzed chemiluminescence of lucigenin (Luc-CL) in the pH range 6.0–11 were investigated. Preliminary experiments found that the CL emission was strongly enhanced or inhibited in the presence of the ILs. The degree of enhancement or inhibition of the CL intensity in the presence of each IL was related to the molecular structure of the IL, the medium used, and the pH. The maximum enhancement of the CL intensity was observed at pH 9.0 (amplification factor?=?443). This decrease in the pH at which maximum CL enhancement occurred and the substantial signal amplification of the Luc-CL may be related to a strong interaction between Cu^II and the imidazolium ring of superior ILs at this pH. Additionally, the formation of IL microdomains in semi-aqueous media permitted more solubility of the product yielded by the Luc-CL reaction (N-methylacridone), which could increase the CL intensity. To obtain consistent data on the catalytic efficiency of Cu^II in the presence of various ILs as well as the corresponding CL emission intensities, fluorescence quantum yields (Φ _F) of lucigenin were measured under the same conditions. Comparison of the data pointed to the mechanism that controls the properties of Luc-CL in the presence of the Cu^II/IL complexes. Based on the catalytic effect of the Cu^II/IL complex and the measurement of the enzymatically generated H₂O₂, a novel, simple, and sensitive CL method for determining glucose with a detection limit (LoD) of 6.5 μM was developed. Moreover, this method was satisfactorily applied to the determination of glucose in human serum and urine samples.

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Graphical Abstract The lucigenin chemiluminescence assay for H₂O₂ and glucose using imidazolium–based ionic liquid derivatives/Cu^II complexes as efficient catalysts at pH 9.0

     

Dispersive Liquid‐Liquid Microextraction of Cu(II) Using a Novel Dioxime for Its Highly Sensitive Determination by Graphite Furnace Atomic Absorption Spectrometry

A dispersive liquid‐liquid microextraction (DLLME) technique was proposed for the enrichment and graphite furnace atomic absorption spectrometric (GFAAS) determination of Cu²⁺ in water samples. In this method a mixture of 480 μL acetone (disperser solvent) containing 26 μg S,S‐bis(2‐aminobenzyl)‐dithioglyoxime (BAT) ligand and 20 μL carbon tetrachloride (extraction solvent) was rapidly injected by a syringe into 5 mL aqueous sample containing copper ions (analyte). Thereby, a cloudy solution formed. After centrifugation, the fine droplets containing the extracted copper complex were sedimented at the bottom of the conical test tube. This phase was collected by a microsyring and after dilution by methanol, 20 μL of it was injected into the graphite tube of the instrument for analysis. Effects of some parameters on the extraction, such as extraction and disperser solvent type and volume, extraction time, salt concentration, pH and concentration of the chelating agent were optimized. The response surface method was used for optimization of the effective parameters on the extraction recovery. Under these conditions, an enrichment factor of 312 was obtained. The calibration graph was linear in the rage of 2–50 μ L⁻¹ Cu²⁺ with a detection limit of 0.03 μg L⁻¹ and a relative standard deviation (RSD) for five replicate measurements of 3.4% at 20 μg L⁻¹ Cu²⁺. The method was successfully applied to the determination of Cu²⁺ in some spring water samples.     

Selective homogeneous liquid-liquid extraction and preconcentration of copper(II) into a micro droplet using a benzo-substituted macrocyclic diamide, and its determination by electrothermal atomic absorption spectrometry

A fast and reliable method was developed for the selective separation and preconcentration of Cu²⁺ ions using homogeneous liquid-liquid extraction using a novel benzo-substituted macrocyclic diamide, 5,6,7,8,9,10-hexahydro-2H-1,13,4,7,10-benzodioatriazacyclo-pentadecine-3,11(4 H,12 H)-dione, as a selective complexing agent. An aqueous solution of Zonyl FSA (FSA) was used as a phase-separation agent at pH 4.5. Electrothermal atomic absorption spectrometry was used for Cu²⁺ determination after preconcentration. The influences of pH, type and volume of the water-miscible organic solvent, concentration of FSA, concentration of the ligand and the effect of diverse ions were investigated. Factorial design and response surface methods were used for the optimization purposes. Under the optimum experimental conditions, 50 ng of Cu²⁺ in 5 mL aqueous sample could be extracted quantitatively into 76 µL of the sediment phase. The maximum preconcentration factor was 65. The calibration curve was linear in the concentration range 0.2 to 4.0 µg L^?1. The detection limit and relative standard deviation were 4 ng L^?1 and 4.6%, respectively. The method was successfully applied to the extraction and determination of Cu²⁺ in natural water samples.     

Effect of temperature on weldline integrity of injection moulded short glass fibre and glass bead filled ABS hybrids

The present study investigated the effect of temperature on weldline strength of injection moulded ABS polymer reinforced with both short glass fibres (GF) and spherical glass beads (GB) over the temperature range 25 to 100 °C. It was noted that weld and non-weld tensile strength of ABS/GF/GB hybrids increased as the concentration of total glass in the hybrids increased. A linear increase in both weld and non-weld tensile strength was found with increasing the hybrid ratio of the glass fibre, χ. Results indicated that weld and non-weld tensile strength for the hybrid at a given temperature can be estimated from the rule of hybrid mixtures. Weld and non-weld tensile strength of the hybrid system decreased with increasing temperature in a linear manner. The rate at which weld and non-weld tensile strengths decreased with temperature was dependent upon the hybrid ratio of the glass fibre, χ, and the total concentration of glass in the hybrids. Weldline integrity factor for the hybrids decreased non-linearly with increasing χ, but increased linearly with increasing temperature.     

Oxidation of Alcohols with 4-Aminopyridinium Chlorochromate Supported on Silica Gel

4-Aminopyridinium chlorochromate supported on silica gel was found to be an efficient reagent for the oxidation of primary and secondary alcohols to the corresponding carbonyl compounds.     

Properties of a high capacity iminodiacetate-agarose adsorbent and its application in a flow system with on-line buffering of acidified samples for accumulation of metal ions in natural waters

Adsorption properties of a fast iminodiacetate-agarose adsorbent, IDA-Novarose, with a capacity of 120-140 mumol/ml were studied for preconcentration of eight transition elements. A FIA-ICP-AES system was used in the study. It was shown that 0.3 ml of the adsorbent, packed in a column, can quantitatively accumulate Cr(3+), Mn(2+), Fe(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+) and Cd(2+) from standard solutions in the pH range between 4 and 8 at high loading flow rates (10-80 ml/min). The rate of adsorption was studied in batch experiments and found to be fast and equal for the divalent metal ions but relatively slow for accumulation of Cr(3+) and Fe(3+). On-line buffering of acidified samples improved the accumulation of metal ions from synthetic samples spiked with humic acid. Quantitative uptakes were observed for most of the studied metals. The accumulation of Cr(3+) was found to be quite sensitive to the ionic strength and some loss of inert complexes of Fe(3+) was also observed. The method was applied to the analysis of certified riverine water (SLRS-3), a tap water and a lake water. With few exceptions the results obtained by ICP-AES after preconcentration agreed well with the certified concentrations and results found by ICP-MS.     

Transport Properties of Simple Fluids from the Soft‐Core Double Yukawa Potential

The present work is concerned with checking a new and simple pair potential function (soft‐core double Yukawa potential) for noble gases by calculation of the transport properties. The viscosity, thermal conductivity and self diffusion coefficient in dilute gas limit in the temperature range of 298‐1400 K are calculated and agreement with the measurements is, in general, within the experimental error. A comparison of the calculated and experimental values of the viscosity, thermal conductivity and the diffusion coefficients yields an average absolute deviation of 0.5%, 1.5% and 1.2%, respectively. Also, the calculated transport properties from this potential have been compared with those calculations via the accurate experimental potential and also the corresponding state.     

Highly Sensitive and Selective Determination of Manganese in Tea Leaves by a Catalytic Kinetic Spectrophotometric Method

The catalytic effect of manganese(II) on the oxidation of barium diphenylamine sulfonate (BDAS) with potassium bromate in sulfuric acid was studied. Progress of the reaction was monitored, spectrophotometrically, by measuring absorbance changes at 547.5 nm. A highly sensitive, selective and simple method was accordingly developed for the determination of trace amounts of Mn(II), with no need for a separation or pre‐concentration step. Effects of reaction time, concentration of reagents, temperature and ionic strength on the reaction rate were studied. In the optimized conditions, manganese could be determined in a range of 1 to 60 ng mL^?1 with a detection limit of 0.2 ng mL^?1. The proposed method was successfully applied to the determination of manganese in tea leaves.     

Analysis of particle contact using frustrated total internal reflection

Meccanica - Within the field of soil mechanics a continuum assumption is generally adopted in order to avoid the complications of modelling micro-mechanical behaviour. However, certain constitutive...