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Rapid, low-cost and efficient assays for penicillinase activity and inhibition are of vital importance for therapeutics and diagnostics of bacterial resistance to antibiotics. Herein we report a novel approach for on-line enzyme assays for penicillinase utilizing capillary electrophoresis-integrated immobilized enzyme reactors (CE-IMERs). The CE-IMERs are fabricated based on penicillinase-mediated...
A tapered-capillary microextraction (tCap-μEx) combining with field-amplified stacking (FASI) method for CE analysis was developed. The tCap-μEx method is based on the construction of a micro solid phase extraction (SPE) column by narrowing the end of a silica capillary from 530µm (inner diameter) to 20µm, enabling the packing of 45µm sorbent particles without a frit. Various parameters that may affect...
Lycii Fructus is widely cultivated in the Northwest China. It is well-known for its antiaging effect in traditional Chinese medicines (TCMs), but the effective components are not clear. In this work, the ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was used to study the antioxidant components of Lycii Fructus through analyzing the spectrum-effect relationship, and...
Novel pyridine-ring containing twisttetraazaacene 9,14-diphenylpyreno[4,5-g]isoquinoline (1) and its full-carbon derivative 9,14-diphenyldibenzo[de,qr]tetracene (2) have been synthesized and fully characterized. Studies showed that compound 1 could identify picric acid (PA) over other common nitro compounds with high selectivity and sensitivity. Upon the addition of PA, the emission peak of compound...
A new, feasible procedure for high-precision bromine isotope analysis using multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is described. With a combination of HR mass resolution mode and accurate optimization of the Zoom Optics parameters (Focus Quad: −1.30; Zoom Quad: 0.00), the challenging problem of the isobaric interferences (40Ar38ArH+ and 40Ar40ArH+) in the measurement...
In order to eliminate boron loss and potential isotopic fractionation during chemical pretreatment of natural samples with complex matrices, a three-column ion-exchange separation/purification procedure has been modified, which ensures more than 98% recovery of boron from each step for a wide range of sample matrices, and is applicable for boron isotope analysis by both TIMS and MC-ICP-MS. The PTIMS-Cs...
β-cyclodextrin modified gold nanoparticles (CD-GNP) were employed as the stationary phase in monolith capillary electrochromatography (CEC) to facilitate enantioseparation. CD-GNP were covalently bound to the surface of the thiolated porous polymer monolithic column. The fabricated enantioselective monolithic column was characterized by a variety of spectroscopic methods. The column exhibited steady...
We have explored a novel dual-function stationary phase which combines both strong cation exchange (SCX) and hydrophobic interaction chromatography (HIC) characteristics. The novel dual-function stationary phase is based on porous and spherical silica gel functionalized with ligand containing sulfonic and benzyl groups capable of electrostatic and hydrophobic interaction functionalities, which displays...
A novel rhodamine-based fluorescent chemosensor (RND) was synthesized that contains two independent fluorophores and acts as a very sensitive, selective and reversible off–on probe for Hg(II). Importantly, this newly developed sensing system exhibited different fluorescent responses toward Hg(II) and Mg(II) at 589nm and 523nm, respectively. RND also displayed detectable color change upon treatment...
The influence of the bending-induced mechanical stress of flexible Nafion ® /GOx/carbon screen-printed electrodes (SPEs) upon the performance of such glucose biosensors has been examined. Surprisingly, such flexible enzyme/polymer-SPEs operate well following a severe bending-induced mechanical stress (including a 180° pinch), and actually display a substantial sensitivity enhancement following...
A method has been described for the direct determination of trace levels of germanium by graphite furnace atomic absorption spectrometry (GFAAS) using chemical matrix modification technique. The stabilization and the pyrolysis temperatures for germanium were investigated with various chemical modifiers including palladium, palladium-magnesium, palladium-strontium and palladium-zirconium. The highest...
A new sequential injection analysis (SIA) method of an electrokinetic flow analysis (EKFA) system for the determination of nitrite-nitrogen is presented in this paper. The proposed system mainly consisted of an electroosmotic pump, two solenoid valves and a spectrophotometer etc. All the pump and valves were controlled by a personal computer automatically. The determination method of nitrite-nitrogen...
An electrokinetic flow analysis system (EKFA) using an electroosmotic pump (Peo) and a bi-directional electrostacking (BDES) unit is introduced in this paper. Large flow range, moderate carrier pressure, low performance voltage and stable flow rate, especially in μlmin -1 level, are the main specialties of the Peo. Diethanolamine, 0.5 mM, is selected as its carrier to improve the pump...
The electrochemistry of l-tyrosine was studied by cyclic voltammetry at a glassy carbon electrode. Although l-tyrosine itself showed very poor electrochemical response, the response could be greatly enhanced by using 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy (HO-TEMPO) as a mediator that enables a sensitive determination of the substrate. An electrocatalytic EC' mechanism with the oxoammonium...
An electroosmotic pump flow injection system is introduced in this paper. According to electroosmotic theory, the pump's properties were described. A large flow range (μl min -1 -ml min -1 ), moderate carrier pressure (>0.15 MPa), reduced performance voltage (<500 V) and stable flow rate (RSD<3.0% in 4 h) are the main properties of the pump. NH 4 OH (0.35...
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