Simultaneous laser-induced fluorescence and contactless-conductivity detection for microfluidic chip

A combined detection system involving simultaneous LIF and contacfless-conductometric measurements at the same place of the microfluidic chip was described. The LIF measurement was designed according to the confocal principle and a moveable contactless-conduetivity detector was used in C^4D. Both measurements were mutually independent and advantageous in analyses of mixtures. Various experimental parameters affecting the response were examined and optimized. The performances were demonstrated by simultaneous detection of Rhodamine B. And the results showed that the combined detection system could be used sensitively and reliably.     

A novel electromagnetic induction detector with a coaxial coil for capillary electrophoresis

A novel electromagnetic induction detector with two inductors for CE was described here.The two inductors were used as signal detection and reference,respectively.The parameters affecting the detector performance(including coil turns,detection distance, excitation frequency,voltage,etc.) were optimized.Under the optimum condition,the feasibility of the detector was examined by analyzing inorganic ions.The fabricated detector showed good linear relationship between the response and the analytes concentrations,with a detection limit of 13μmol/L for Na~+(S/N = 3).A variety of advantages,such as simple construction, ease of operation,and considerably universal response,suggested this novel detector a promising application prospect in analytical area.     

气相色谱分析中是否一定要用质谱检测器？

The detector, as well as being an essential supporting device for the gas chromatography (GC) has also played a critical role in the development of the technique as a whole. The mass spectrometer (MS) is still the commonly praised detector as before. In fact, the information of fragmentation patterns is seldom used in practice, and the GC-MS instrument is even more expensive. For today’s analytical problems, it seems that element specific detectors can and should be used for many applications rather than GC-MS.     

A new anode material LiMoS_2 for use in rechargeable Lithium Ion Batteries

The novel applications of molybdenum disulfide in recent research were reviewed, such as in lubricant, catalyst and photoelectrochemical solar cells. Recently, we found that LiMoS2 is a good candidate for new anode materials for lithium ion batteries with high lithium storage capacity. Here, the anode material LiMoS2 was synthesized by a hydrothermal method at 150oC and the electrochemical characterization as an anode material for lithium ion batteries was examined. The preparation procedur…     

Simple and cost-effective determination of ciprofloxacin hydrochloride by electrical micro-titration

By employing an electrical micro-titration system, in which a capacitively coupled contactless conductivity detector(C4D) was used to monitor the reaction process in real time, herein a novel method for determining ciprofloxacin hydrochloride(CIPHCl) was developed for the first time. Mode 1: Standard CIPHCl solutions at different concentrations were loaded into reaction cells, respectively, and were titrated with standard Ag+. Upon the titration, the formation of a precipitate alters the number of ions in the solution, raising the change of conductivity, which was monitored by a special C~4 D to construct a titration curve. The endpoint of the titration was located from the peak of the curve. Between the elapsed time and the initial concentration of titrand, a linear relationship was established over the range of2.0–8.0 mmol/L. Mode 2: Standard Fe~(3+) took the place of Ag~+, and was used as titrant to recognize ciprofloxacin contributed to the formation of complexation, which also resulting a change of solution conductivity. Under optimized conditions, a working range of 1.0–5.0 mmol/L CIPHCl was found. Because the reaction solutions were isolated from the working electrodes, this pioneer work shows significant simplicity and cost-effectiveness, by eliminating the requirements for detector exchange/renewal between different measurements, and by involving no auxiliary chemicals. Both of the two approaches were applied successfully to determine CIPHCl in tablet samples. And the results were in good agreement with those obtained by reference method.     

Iodide analysis by ion chromatography on a new stationary phase of polystyrene-divinylbenzene agglomerated with polymerized-epichlorohydrin-dimethylamine

A new stationary phase for iodide ion analysis has been developed. The cationic polymerepichlorohydrin-dimethylamine(PEPI-DMA) was served as modifier in synthesizing polyelectrolyte sorbents and the macroporous polystyrene-divinylbenzene(PS-DVB) resin was used as support. The positively charged polymer(PEPI-DMA) was electrostatically bonded to a negatively charged particle(PS-DVB sulfonated). The new stationary phase was characterized by scanning electron microscopy(SEM), Fourier transform infrared(FTIR), elemental analysis, chemical adsorption and desorption measurements. The chromatographic evaluation of the new stationary phase was performed using various anions with a conductivity detector. The new stationary phase was also applied to the determination of iodide directly with a DC amperometric detector using a platinum working electrode and an Ag/Ag Cl reference electrode. The chromatographic conditions were optimized and the eluent solution contained 5 mmol/L HNO3 and 15 mmol/L Na NO3 at a flow rate of 1.0 m L/min and column temperature of 30 8C. The applied voltage of the DC amperometric detector was 0.9 V. Under the optimum conditions, the linear range of the method was 0.2–50 mg/L for iodide ion with a correlation coefficient of 0.9990. The detection limit was 0.05 mg/L(calculated at S/N = 3) and the relative standard deviations(RSD, n = 6) were all less than 1% for retention time, peak area and peak height. This method was also utilized for the determination of iodide ions in samples of povidone iodine solution and kelp samples with satisfactory results.     

安培检测芯片毛细管电泳及其初步应用

An end-channel amperometric detector with a guide tube for working electrode was designed and integrated on a home-made glass microchip. The guide tube was directly patterned and fabricated at the end of the detection reservoir, which made the fixation and alignment of working electrode relatively easy. The fabrication was carried out in a two-step etching process. A 30 μm carbon fiber microdisk electrode and Pt cathode were also integrated onto the amperometric detector. The baseline separation of dopamine (DA), catechol (CA) and epinephrine (EP) was achieved within 80 s. Relative standard deviations of not more than 5.2% were obtained for both peak currents and migration times of DA and CA (n=5). Using standard adding method, DA in tLrine and plasma samples was detected. The recoveries were in the range of 83%—103%.     

电荷耦合器件检测器在毛细管电泳中的应用进展

Charge-coupled device detector is a new multi-channel optics detector and the progress of its application in capillary electrophoresis has been reviewed with 49 references.     

Approaches to the liquid chromatographic determination of carboxylic acids using potentiometric detection with a metallic copper electrode

Summary A metallic copper electrode is evaluated as a potentiometric detector for carboxylic acids. The application of this device to ion-exchange chromatography is illustrated by the determination of oxalate in urine. Oxalate was selectively detected in the presence of a 100-fold excess of sulphate after separation on a low-capacity methacrylate anion-exchange column using 0.7mM potassium hydrogen phthalate at pH 7.1 as eluent. Calibration plots were linear up to 50ppm of oxalate. Potentiometric detection has also been applied to ion-exclusion chromatography using 0.005% phosphoric acid as eluent. With this method detection limits of 0.2, 2.1, 5.0 and 5.3μg were obtained for formic, acetic, propionic and iso-butyric acids, respectively.     

Combination of ionic liquid dispersive liquid-phase microextraction and high performance liquid chromatography for the determination of triazine herbicides in water samples

A temperature-controlled ionic liquid dispersive liquid-phase microextraction in combination with high performance liquid chromatography was developed for the enrichment and determination of triazine herbicides such as cyanazine,simazine,and atrazine in water samples.1-Octyl-3-methylimidazolium hexafluorophosphate([C8MIM][PF6]) was selected as the extraction solvent.Several experimental parameters were optimized.Under the optimal conditions,the linear range for cyanazine was in the concentration range of 0.5–80 mg/L and the linear range for simazine and atrazine was in the range of1.0–100 mg/L.The limit of detection(LOD,S/N = 3) was in the ranges of 0.05–0.06 mg/L,and the intra day and inter day precision(RSDs,n = 6) was in the ranges of 3.2%–6.6% and 4.8%–8.9%,respectively.Four real water samples were analyzed with the developed method,and the experimental results showed that the spiked recoveries were satisfactory.All these exhibited that the developed method was a valuable tool for monitoring such pollutants.     

水为洗脱剂的静电离子色谱-增强电导检测法测定常见的无机阴离子（英文）

To enhance the conductivity detection sensitivity of common anions(Na-anions) in electrostatic ion chromatography(EIC) by elution with water,a conductivity enhancement column packed with strong acid cation exchange resin in the H-form was inserted between an octadecyl silane(ODS)-silica separation column modified with zwitterionic surfactant(CHAPS: 3-{(3-cholamidopropyl)-dimethylammonio}propanesulfonate) and a conductivity detector.Specifically,the Na-anion pairing is converted to H-anion pairing after the EIC separation and then detected sensitively by the conductivity detector.The effects of conductivity enhancement and suppression in the EIC by the enhanced conductivity detection were characterized for the common strong acid anions such as SO2-4,Cl-,NO-3,I-and ClO-4 and weak acid anions such as F-,NO-2,HCOO-,CH3COO-and HCO-3.For the conductivity enhancement effect in the EIC,it is found that the conductivity of measured for all strong acid anions(Na-anions) was enhanced according to the theoretical conductivity predicted for H-anions and that of the measured for weak acid anions was suppressed depending on their pKa of H-anions.For the calibration linearity in the EIC,the strong acid anions were linear(r2=0.99-1.00) because the degree of dissociation is almost 1.0 over all the concentration range and that of the weak acid anions was non-linear because the degree of dissociation decreased by increasing the concentration of the weak acid anions.In conclusion,the EIC by enhanced conductivity detection was recognized to be useful only for the strong acid anions in terms of conductivity detection and calibration linearity.     

Comparative Analysis of Indoor Levels of Suspended Particulates and Nitrogen Dioxide a Few Hours later after an Asthmatic Attack

Suspended particulates （TSP） and nitrogen dioxide （NO2） are known respiratory irritants linked to asthma aggravation. This pilot study was designed to investigate the role of these pollutants on the frequency of asthmatic attack on two of the inhabitants of a household. The surveillance of TSP and NO2 in this household commenced a few hours later, after one of the occupants suffered an attack. The TSP load determination was done using a High Volume Gravimetric sampler and a light scattering method via a Haz-Dust 10 μm particulate monitor. Palmes Diffusion tubes for NO2 and a portable Crowcon Gasman toxic gas detector were utilized for NO2 screening. In the first day of monitoring in the living room, the in situ particulate sampler （Haz-Dust） recorded a mean TSP level of 26,000 μg·m^-3. A confirmatory test with the eight hour average Gravimetric sampler gave 25,833 μg·m^-3. With the use of the Gasman toxic gas detector for NO2, the NO2 concentration for the first few hours of sampling was lower than 188 μg·m^-3, the detection limit of this instrument. However, the exact NO2 concentrations for the 7 day monitoring after the attack were 27.50 μg·m^-3 （kitchen） and 12.03 μg·m^-3 （living room） as recorded by the Palmes diffusion tubes.     

Simple Method for Simultaneous Quantitation and Fingerprint Analysis of Ginkgo biloba Tablets by High Performance Liquid Chromatography-UV-Evaporative Light Scattering Detector

By optimizing the separation and analytical conditions, a reliable, simple and accurate high-performance liquid chromatography(HPLC) method coupled with ultraviolet(UV) and evaporative light scattering detector(ELSD) was developed for the simultaneous determination of lactones and flavonoid, that is, bilobalide, ginkgolide A, ginkgolide B, and rutin, in more than 10 batches of Ginkgo biloba tablets from different pharmaceutical companies. The method could also be applied to fingerprint research, for a more general evaluation of the quality of this preparation. The separation of the components was achieved on a Hanbon C18 column with gradient elution using water and methanol containing 0.1% trifluoroacetic acid(TFA). The column temperature was 30 ℃ and the flow-rate of the mobile phase was 0.6 mL/min. The drift tube temperature of the ELSD was set at 100 ℃, and the nitrogen flow-rate was 2 L/min. Good linear relationships were shown with correlation coefficients for analytes exceeding 0.9913. The limits of detection(LODs, S/N=3) and the limits of quantitation(LOQs, S/N=10) were 0.00887--0.0508 μg/μL and 0.0171-0.0636 μg/μL, respectively, on the column. The relative standard deviations(RSD) of the analytes were less than 3.61% for intraday and 3.70% for interday, respectively. The average recovery rates obtained were in the range of (97.3±4.3)% to (101.9±3.1)% for all the compounds. The results of quantitative and fingerprint analysis proved that the contents of the components were totally similar in the preparation of Ginkgo biloba tablets from the same pharmaceutical company; whereas, they varied significantly in the preparations of Ginkgo biloba tablets from different companies.     

A simple and convenient method for direct α-chlorination of ketones with ammonium chloride and Oxone~

When ketones were treated with ammonium chloride and Oxone~ in MeOH at room temperature,a directα-chlorination of ketones was occurred and a series of the corresponding a-chloroketones were obtained in moderate to good yields after 24 h.In this reaction,ammonium chloride was used as the source of chlorine and Oxone~ was used as an oxidant.This method was simple, convenient and providing a novel procedure for preparation of a-chloroketones.     

Determination of 15 polycyclic aromatic hydrocarbons in lotus root by QuEChERS-high performance liquid chromatographyEI北大核心CSCD

A method for the determination of 15 priority polycyclic aromatic hydrocarbonsPAHsin lotus root by QuEChERS technique combined with high performance liquid chromatography HPLC was established. Lotus root samples were extracted by acetonitrilefiltrated after salting out and purified by C18 and primary secondary aminePSAsorbent. Then the 15 kinds of PAHs were analyzed by HPLC with diode array detector or fluorescence detector after being separated by Athena PAHs column. When the 15 kinds of PAHs were analyzed by diode array detectorthe linear relationships were good between 0.02 and 1.0 mg/L with the correlation coefficients above 0.99 for all the 15 kinds of PAHs. The limits of quantitation were 0.02 mg/kg for allthe average recoveries of the 15 kinds of PAHs were 84.7%-117.1%and the relative standard deviations were 0.73%-11%. When the 14 kinds of PAHsexcept for acenaphthyleneanalyzed by fluorescence detectorthe linear relationships were good between 0.001 and 1.0 mg/L with the correlation coefficients above 0.99 for all the 14 kinds of PAHs except for acenaphthylene. The limits of quantitation were 5 μµg/kg for allthe average recoveries of the 14 kinds of PAHsexcept for acenaphthylenewere 69.1%-111.8%and the relative standard deviations were 0.18%-9.7%. Diode array detector and fluorescence detector are complementary. Diode array detector can analyze all the PAHsbut its sensitivity is relatively low. Fluorescence detector is not suitable for acenaphthylene with weak fluorescence signalbut its sensitivity is much higher than that of diode array detector. This method is suitable for simultaneously and quickly determination of 15 kinds of PAHs in lotus root. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

用对氨基苯酚改性的碳纳米管糊电极同时测定羟胺和苯酚(英文)

A carbon paste electrode that was chemically modified with multiwall carbon nanotubes and p-aminophenol was used as a selective electrochemical sensor for the simultaneous detection of hydroxylamine (HX) and phenol. Cyclic voltammetry, double potential-step chronoamperometry, square wave voltammetry (SWV), and electrochemical impedance spectroscopy were used to investigate the use of p-aminophenol in the carbon nanotubes paste matrixes as a mediator for the electrocatalytic oxidation of HX and phenol in aqueous solution. The coefficient of electron transfer and catalytic reaction rate constant were determined using the electrochemical methods. Under optimized conditions, the electrocatalytic oxidation current peaks for HX and phenol increased linearly with concentration in the range of 0.5-180.0 and 10.0-650.0 μmol/L for HX and phenol, respectively. The detection limits for HX and phenol were 0.15 and 7.1 μmol/L, respectively. The anodic potential peaks of HX and phenol were separated by 0.65 V in SWV. Because of good selectivity and sensitivity, the present method provides a simple method for the selective detection of HX and phenol in practical samples such as water samples.     

Preparation of a pH-sensitive pantoprazole-imprinted polymer and evaluation of its drug-binding and -releasing properties

The aim of this work was to synthesize a pantoprazole-imprinted polymer(MIPs)and study its binding and release properties in an aqueous media.Methacrylic acid(MAA),methacrylamide(MAAM),hydroxyethyl methacrylate(HEMA),and 4-vinyl pyridine(4VP)were tested as functional monomers.Different solvents were also applied as polymerization media under heat or UV radiation.The optimized MIP was prepared in chloroform as a solvent,4-vinyl pyridine as a functional monomer,and ethylene glycole dimethacrylate(EGDMA)as a crosslinker monomer under UV irradiation.Binding and release properties of MIP were studied in comparison with a non-imprinted polymer(NIP)in aqueous media,at different pH values.The protective effect of polymer for drugs against acidic conditions was evaluated at pH 2.Results indicated that the MIP had superior binding properties compared to NIP for pantoprazole.The percentage of drug released from MIP was significantly less than from NIP at all pH values,which was attributed to the presence of imprinted cavities in the MIP matrix.MIP also had a stronger protective effect for pantoprazole in acidic media,in comparison with NIP.     

Capillary Electrophoresis for the Simultaneous Determination of Metals by Using Ethylenediamine Tetraacetic Acid as Complexing Agent and Vancomycin as Complex Selector

A new separation system of capillary electrophoresis for the simultaneous determination of metals by using ethylenediamine tetraacetic acid （EDTA） as complexing agent and employing vancomycin as complex selector was described. The Z-shape cell capillary electrophoresis was used to enhance the sensitivity for the determination of the complexes of Cu（Ⅱ）, Ni（Ⅱ）, Co（Ⅱ） and Fe（Ⅲ） with EDTA. The partial filling method （co-current mode） was used in order to increase the selectivity of the electrophoretic method, meanwhile vancomycin was not present at the detector path during the detection of metal-EDTA complexes. The vancomycin concentration, phosphate concentration and pH of the buffer strongly influenced mobility, resolution and selectivity of the studied analytes. Under the optimal condition, the relative standard deviations （n=5） of the migration time and the peak area were less than 3.14% and 7.35%, respectively. Application of the Z-shape cell capillary electrophoresis method with UV detection and vancomycin loading led to the reliable determination of these metal ions in tap water and the recoveries were 97%-101%. The detection limits based on a signal to noise ratio of 3 ： 1 were found in the range of 2-10 μg·L^-1.     

Determination of metoprolol in rabbit blood using capillary electrophoresis with laser-induced fluorescence detection

This work described a sensitive method for determination of metoprolol in rabbit plasma.The method involved purification by ultrafiltration,derivatization with fluorescein isothiocyanate,determination by capillary electrophoresis(CE) coupled with laser-induced fluorescence(LIF) detector.Other components in plasma including a variety of amino acids and proteins did not interfere with the determination of metoprolol in experimental condition.The assay had a wide range(2.0-500 ng/mL) of linearity and a detection limit of 0.8 ng/mL.The intra- and inter-day precisions were satisfactory with relative standard deviation(RSD) less than 10.0%and accuracy within 10.0%.This method was successfully applied to pharmacokinetic study of metoprolol in rabbit blood.     

Parallel and serial dual electrode detectors for capillary electrophoresis

Application of parallel and serial dual electrode detectors for capillary electrophoresis was first described. In parallel dual electrode approach, two 100 μm-diameter Cu disks arranged side by side were used as the dual working electrode for the simultaneous determination of a mixture of carbohydrates and amino acids. In serial dual electrode approach, two working electrodes were arranged in a disk-ring manner for the simultaneous determination of both cysteine and cystine; the disk electrode was Hg/Au serving as the upstream electrode, the ring electrode was 5% CoPC carbon paste serving as the downstream electrode.