Flow injection spectrophotometric determination of vitamin E in pharmaceuticals,milk powder and blood serum using potassium ferricyanide-Fe(Ⅲ) detection system

<正>A simple and sensitive flow injection spectrophotometric method is reported for the determination of vitamin E using potassium ferricyanide-Fe(Ⅲ) detection system.In the presence of vitamin E,Fe(Ⅲ)/ferricyanide reduces.The in situ reduced ions are then reacted with unreduced portion of ferricyanide/Fe(Ⅲ) to make soluble Prussian blue,which is monitored at absorption wavelength of 735 nm.Linear calibration graph was obtained in the concentration range of 0.1-40μg mL~(-1).The relative standard deviations (n=4) were in the range of 1.1-3.6%,with limits of detection(3 s blank) of 0.04μg mL~(-1).The proposed method allowed 12 injections h~(-1).The method is applied to determine vitamin E in pharmaceuticals,infant milk and blood serum samples using hexane extraction with the recoveries in the range of 93±3 to 97.5±4%.The method is validated using certified reference materials SRM 968c for blood serum samples.     

Application of potassium ferricyanide in the spectrophotometric determination of captopril

A novel method for the determination of captopril by speetrophotometer is described in this paper. The experiment is based on the fact that Fe(Ⅲ) is reduced to Fe(Ⅱ) by captopril, then the in situ formed Fe(Ⅱ) reacts with potassium ferricyanide to give the soluble prussian blue at pH 4.00, and its maximal adsorption wavelength (λmax) is 735 nm. Good linear relationship is obtained between the absorbance and the concentration of captopril in the wide range of 0.05-20 μg/mL. The linear regression equation is A = -0.04314 + 0.11423C (μg/mL) with a correlation coefficient R = 0.9998. The detection limit (3a/k) is 0.04 μg/mL, the molar absorption coefficient is 2.5×104 L/mol cm. By mensurating the absorbance of soluble prussian blue, the indirect determination of eaptopril can be obtained. This method has been successfully applied to determination of captopril in pharmaceutical samples.Analytical results obtained are satisfactory.     

Determination of Protein via Resonance Light Scattering Technique with （NH4）2SO4

Be able to form large particles with protein via electrostatic force to enhance the intensity of resonance light scattering(RLS),(NH4)2SO4 was used as a RLS probe to determine bovine serum albumin(BSA),human serum albumin(HSA) and ovum albumin(OVA).The experimental conditions were investigated,including the acidity and saturation degree of (NH4)2SO4.Under the optimum conditions,the enhanced RLS intensity is proportional to the concentration of BSA,HSA and OVA in the ranges of 5×10-8―1×10-6,2.5×10-8―8×10-7 and 5×10-8―1.5×10-6 mol/L,respectively.The detection limits for BSA,HAS and OVA are 6.6×10-9,3.8×10-9 and 7.4×10-9 mol/L,respectively.The effects of foreign substances were also examined.The practical and synthetic samples were analyzed with satisfactory results.     

Capillary electrophoresis with electrochemiluminescence detection for the analysis of quinolone drugs and pharmacokinetics study

A novel method for the determination of two quinolone drugs norfloxacin （NOR） and levofloxacin （LVX） was described by capillary electrophoresis with electrochemiluminescence detection. The good relationship （r ≥ 0.9991） between peak area and concentration of analytes was established over two orders of magnitude. The limits of detection （LOD, S/N = 3） in standard solution are 4.8 × 10^-7 mol/L for NOR and 6.4 × 10^-7 mol/L for LVX, respectively. The limits of quantitation （LOQ, S/N = 10） in real human urine samples are 1.2 × 10^-6 mol/L for NOR and 1.4 × 10^-6 mol/L for LVX, respectively. The present method was successfully applied to the determination of NOR and LVX in human urine and the studv of oharmacokinetics of NOR.     

Determination of diastereoisomeric alkaloids in urine by capillary electrophoresis with electrochemiluminescence detection

A new and simple capillary electrophoresis with electrochemiluminescence detection was developed for the separation and the quantification of a pair of diastereoisomenc alkaloids（ephedrine and pseudoephedrine）.The limits of detection（S/N = 3） were 4.5×10^-8 mol/L for ephedrine and 5.2×10^-8 mol/L for pseudoephedrine,respectively.The RSDs of migration time and peak area were less than 1.3 and 2.5%（n = 5）,respectively.The applicability of the propose method was illustrated in the determination of ephedrine and pseudoephedrine in human urine,ephedrine in nasal drops,and the monitoring of pharmacokinetics for pseudoephedrine.     

Simultaneous Determination of Epinephrine, Noradrenaline and Dopamine in Human Serum Samples by High Performance Liquid Chromatography with Chemiluminescence Detection

A simple, rapid and accurate high performance liquid chromatographic （HPLC） technique coupled with chemiluminescence （CL） detection was developed for the simultaneous determination of epinephrine （E）, noradrenaline （NA） and dopamine （DA）. It was based on the analyte enhancement effect on the CL reaction between luminol and potassium ferricyanide. The effects of various parameters, such as potassium ferricyanide concentration, luminol concentration, pH value and component of the mobile phase on chromatographic behaviors of the analytes （E, NA and DA） were investigated. The separation was carded out on C18 column using the mobile phase of 0.01 mol/L potassium hydrogen phthalate solution and methanol （92 ： 8, V/V）. Under the optimum condi- tions, E, NA and DA showed good linear relationships in the range of 1 × 10^-8 -5 × 10^-6, 5.0× 10^-9 -1.0× 10^-6 and 5.0×10^-9-1.0× 10^-6 g]mL respectively. The detection limits for E, NA and DA were 4.0×10^-9, 1.0× 10^-9 and 8.0 × 10^-10 g/mL. The proposed method has been applied successfully to the analysis of E, NA and DA in human serum samples.     

高效液相色谱法测定马吲哚片含量

The present paper deals with the HPLC method used for the determination of mazindoI tablets,The op-timum conditions were as follows:ZORBAX CN column(4.6mn× 25cm);methanol/0.0l mol/L ammoniumdibasic phosphate buffer(8:2)as mobile phase and UV-254 detection. The proposed method is simple andrapid without the need of any preliminary separation,The results obtained are satisfactory both in recovery and precision.     

Simultaneous determination of flavonoids and anthraquinones in chrysanthemum by capillary electrophoresis with amperometry detection

<正>A high-performance capillary electrophoresis with amperometry detection method(CE-AD) has been developed for the analysis of flavonoids and anthraquinones(emodin,kaempferol,apigenin,luteolin and rhein) in chrysanthemum.Under optimum conditions,these five analytes were base-line separated within 17 min using a borate-phosphate running buffer(1.5×10~(-2) mol/L borate-3×10~(-2) mol/L phosphate running buffer,pH 9.0) at a working potential of +0.90 V(vs.SCE) and a separation voltage of 19 kV.The linear relationship between concentration and current response was obtained with detection limits(S/N = 3) ranging from 1.0×10~(-7) to 2.1×10~(-7) g/mL for all analytes.This proposed method was successfully used in the analysis of four kinds of chrysanthemum with relatively simple extraction procedures,the assay results were satisfactory.     

异丙肾上腺素在硅酸铋离子交换薄层上的选择性分离与测定（英文）

A simple and sensitive method for the separation and determination of isoproterenol from other doping drugs has been developed on thin layers of bismuth silicate,a synthetic inorganic ion exchanger as adsorbent in thin layer chromatography(TLC).A mixture of methanol and 0.1 mol/L formic acid(3∶7,v/v)was employed as the mobile phase.The development time was 32 min.The quantitative measurement were performed with a Camag TLC Scanner-3 at wavelength(λ)of 410 nm.The isoproterenol recovery in this procedure was 98.9%.The linear correlation coefficient was greater than 0.987 1 and the relative standard deviation(RSD)was less than 0.94.The limit of detection(LOD)and limit of quantification(LOQ)were 7.7×10-7mol/L and 3.85×10-6mol/L,respectively.This method has been applied in the determination of isoproterenol in dosage forms and in biological fluids.     

Analysis of Vitamin K3 by a Fluorescent Spectroelectrochemistry Method

A simple and sensitive spectroelectrochemistry method for the determination of vitamin K 3 was developed by combining electrolysis and fluoremetry. This method was based on that vitamin K 3 was reduced at a glassy carbon electrode, and its product with characteristic fluorescence at 420 nm was determined with excitation wavelength at 309 nm. Under optimized electrochemical reaction conditions and fluorescent experiment parameters, the fluores-cence intensity was proportional to the concentration of vitamin K 3 in a range from 3.50×10 ?7 to 1.05×10 ?5 mol/L with a correlation coefficient of 0.9991, and detection limit was estimated to be 7.50×10 ?8 mol/L at a signal/noise ra-tio of 3. The relative standard deviation was less than 4.3%(n=5) and the recovery was in a range of 97%―105% for the determination of vitamin K 3 in pharmaceutical preparations. The result is satisfactory for the determination of vi-tamin K 3 as comparison to that from HPLC method.     

Chromatographic separation of cerium(Ⅲ) in L-valine medium using poly[dibenzo-18-crown-6]

A column chromatographic method has been developed for the separation and determination of cerium(Ⅲ) using poly[dibenzo-18-crown-6]. The separation was carried out in L-valine medium. The adsorption of cerium(Ⅲ) was quantitative from 1×10-1 to 1×10-4 mol/L L-valine. Amongst the various eluents, 1.0-8.0 mol/L hydrochloric acid, 1.0-8.0 mol/L hydrobromic acid, 1.0-8.0 mol/L perchloric acid, 1.0-2.0 mol/L sulfuric acid and 4.0-5.0 mol/L acetic acid, were found to be the efficient eluents for cerium(Ⅲ). The capacity of poly[dibenzo-18-crown-6] for cerium(Ⅲ) was (0.428±0.01) mmol/g. The method was applied to the separation of cerium(Ⅲ) from associated elements link uranium(Ⅵ) and thorium(Ⅳ). It was also applied for the determination of cerium(Ⅲ) in geological samples. The method is simple, rapid and selective with good reproducibility (approximately±2% ).     

Determination of zidovudine using anion exchange chromatography with integrated pulsed amperometric detection

A rapid and practical method for direct detection of zidovudine in high performance anion exchange chromatography(HPAEC) has been developed with integrated pulsed amperometric detection(IPAD).Dionex AS 18(250 mm×2 mm) and AG 18 (50 mm x 2 mm) columns and 11 mmol/L NaOH solution were used for separation.Multi-step potential waveform parameters were optimized to maximize the signal-to-noise ratio(S/N).Utilizing an optimized waveform,the repeatability(intra-day) precision and intermediate(inter-day) precision are obtained with relative standard deviation(RSD) of 1.88,2.27,respectively.The limit of quantification(LOQ) and limit of detection(LOD) were found to be 9.70,3.0 ng/mL,respectively,with correlation coefficients of 0.9992 over concentration range 0.01-10μg/mL.The present method was successfully applied to the determination of zidovudine in human plasma.The recoveries of plasma sample spiked by 0.7μg/mL,2.7μg/mL obtained were 95.3-101.5%, with relative standard deviation(RSD) of 2.54%,2.21%,respectively.     

Determination of Metamizole Sodium by Cyclic Voltammetry Under Microwave Activation

<正>Microwave radiation was applied to the detection of metamizoie sodium by cyclic voltammetry.The electrochemical characteristics of metamizoie sodium were studied by cyclic voltammetry at GC electrode under microwave radiation and a considerable current enhancement was observed for metamizoie sodium in aqueous 0.05 mol/L H_2SO_4.Under the optional conditions,metamizoie sodium was determined in the absence and presence of microwave activation.In the absence of microwave activation cyclic voltammogram of metamizoie sodium shows good linear relationship in a concentration range of 8.0×10~(-5)—1.0×10~(-3) mol/L in aqueous 0.05 mol/L H_2SO_4 with a detection limit of 6.75×10~(-6) mol/L(S/N=3) and the equation of linear regression is I_p=12.973c-0.1905(R~2=0.9996,n=6);in the presence of 80 W microwave activation cyclic voltammogram of metamizoie sodiumin shows good linear relationship in a concentration range of 4.0×10~(-5)—1.0×10~(-3) mol/L in aqueous 0.05 mol/L H_2SO_4 with a detection limit of 4.41×10~(-6)mol/L(S/N=3) and the equation of linear regression is I_p=25.107c-0.1193(R~2=0.9973,n=7).The current in the presence of 80 W microwave activation increases to about 2 orders of magnitude compared with that in the absence of microwave activation.The proposed method in the presence of microwave activation showed high selectivity and sensitivity,and the sampling of the disposal method is simple.The method was verified by the determination of Metamizoie Sodium tablet with satisfactory results.     

Electrochemical Behavior of Mitoxantrone and Its Determination at a Pt／C Implanted Modified Microelectrode

In a 0.02 mol/L Na2HPO4-KH2PO4(PBS) buffer solution(pH=6.82), the electrochemical behavior of mitoxantrone was studied by linear-sweep voltammetry and cyclic voltammetry at a Pt/C ion implantation modified microelectrode. A sensitive reduction peak was observed. The peak potential was -0.72 V(vs.SCE), the peak current was proportional to the concentration of mitoxantrone within the ranges of 7.0×10-8-9.0×10-7 mol/L and 1.0×10-6-2.4×10-5 mol/L, with a detection limit of 4.0×10-8 mol/L. The linear correlation coefficients were 0.9994 and 0.9992, respectively. This method has been applied to the direct determination of mitoxantrone in simulated urine. The recoveries were in the range from 96.2% to 105.9%. The reduction process was a quasi-reversible one with adsorptive characteristics at the Pt/C microelectrode. The electrode reaction rate constant ks and the electron transfer coefficient α of the system were determined to be 4.5 and 0.65 s-1, respectively. The experiments showed that Pt element had surely been implanted into the surface of the carbon fiber, and the atomic Pt improved the electrocatalytic activity. The Pt/C microelectrode had a good stability and reproducibility.     

高效液相色谱法测定人血清中α－细辛醚的方法

The HPLC method for analysis of α-Asaricin in human serum is simple, sensitive and accurate,A goodlinear correlation between α-Asaricin peak height and its concentration was obtained when α-Asaricin content liein the range of 4. 81×10￣(-9)～9. 61×10￣(-7) mmol/L.The lowest detection limit was 4.81×10￣(-9) mmol/L for serumsample.The recovery was 99.2±1.15%.The within day and day-to-day CVs were all less than 5.3%.Themethod is adequate for the pharmacokinetic study of α-Asaricin in human body.     

环丙沙星-钨硅多金属氧酸盐的制备及热分解动力学

A new polyoxometalate （CPFX·HCl）3H4SiW12O40·10H2O was prepared from ciprofloxacin hydrochloride and H4SiW12O40·nH2O in aqueous solution, and characterized by elemental analysis, IR spectra and DTA-TG-DTG techniques. The IR spectrum confirmed the presence of Keggin structure and the characteristic functional group for ciprofloxacin in the compound. The TG-DTA-DTG curves showed that its thermal decomposition was a four-step process consisting of simultaneous collapse of Keggin type structure. The residue of decomposition was the mixture of WO3 and SiO2, confirmed by X-ray diffraction and IR spectroscopy. The decomposition mechanism and nonisothermal kinetic parameters of the polyoxometalate were obtained from an analysis to the TG-DTG curves by the single scanning methods （the Achar method and Coats-Redfern method） and the multiple scanning methods （the Kissinger method, Flynn-Wall-Ozawa method and Starink method）. The results indicate that the kinetic equationswith parameters describing the thermal decomposition reaction are dα/dt=6.65×10^6[3（1-α）^2/3]e^-10495.5/T with E=87.26 kJ/mol and A=6.65×10^6 s^-1 for the second step,dα/dt=7.01×10^9（1-α）e^-18770.7/T with E=156.06 kJ/mol and A=7.01×10^9 s^-1 for the third step,dα/dt=9.77×10^43[（1-α）^2]e^-88980.0/T with E=739.78 kJ/mol and A=9.77×10^43 s^-1 for the fourth step.     

Determination of resveratrol in red wine by solid phase extraction-flow injection chemiluminescence method

A sensitive flow injection chemiluminescence method has been developed for the detection of resveratrol in red wine based on the fact that resveratrol can greatly enhance chemiluminescence reaction between KMnO_4 and HCHO in sulfuric acid medium. Analytes were pre-concentrated on solid sorbents (C_(18) solid-phase extraction cartridges).Under the optimum conditions,the proposed method allows the measurement of resveratrol over the range of 1.32×10~(-8) to 1.32×10~(-5) mol/L with a detection limit of 3.30×10~(-9) mol/L,and the relative standard deviation for 1.32×10~(-5) mol/L resveratrol (n=11) is 3.8%.This method has been successfully applied for the determination of the resveratrol in red wine.Furthermore,the possible reaction mechanism was also discussed.     

Cobalt Determination by Means of Flow Injection On-line Sorbent Preconcentration-Flame Atomic Absorption Spectrometry with 1-Nitroso-2-naphthol as a Complexing Reagent

The suitability of 1-nitroso-2-naphthol(NN) as a complexing agent for on-line preconcentration of cobalt eluted on the C_(18) microcolumn by means of the FI-FAAS system was tested. Various parameters affecting the complex formation and its elution were optimized. A 2.3×10~(-3) mol/L reagent solution and the aqueous sample solution acidified with 0.1％ (volume fraction) nitric acid were on-line mixed (6.4 mL/min) on a reaction coil set at (65±1)℃ and flowed through the microcolumn for 30 s. The pH of the mixed solution was adjusted to 3—4 with HNO_3(1 mol/L) or NaOH(1 mol/L). The adsorbed complexes in the microcolumn were eluted into the nebulizer of FAAS in 10 s with ethanol acidified with 1％ HNO_3(3.0 mL/min). A good precision(1.6％ for 100μg/L Co(Ⅱ), n=10), a high enrichment factor 17.2, with detection limit (3σ) 3.2μg/L, and sample throughput (90 h~(-1)) were obtained. The method was applied to the certified reference materials(CRMs), NBS-362 and NBS-364, for the determination of cobalt and the results were in good agreement with the certified values.     

以3,4-二羟基肉桂酸为介质的多壁碳纳米管糊电极用于检测药物和尿液样品中的谷胱甘肽(英文)

A sensitive and selective electrochemical sensor for the determination of glutathione(GSH) was developed using a modified multiwall carbon nanotube paste electrode with 3,4 dihydroxy cinnamic acid as a mediator.This modified electrode showed very high electrocatalytic activity for the anodic oxidation of GSH.Under the optimized conditions,the electrocatalytic peak current showed a linear relationship with GSH concentration in the range of 0.5-400.0 μmol/L with a detection limit of 0.1 μmol/L GSH.The relative standard deviations for seven successive assays of 5.0 and 25.0 μmol/L GSH were 2.2% and 2.7%,respectively.The modified electrode was used for the determination of GSH compounds in real urine samples.     

A novel method for Co(Ⅱ) and Cu(Ⅱ) analysis by capillary electrophoresis with chemiluminescence detection

Based on the fact that some metal ions can catalyze the chemiluminescence(CL)reaction of luminol with K_3Fe(CN)_6,a novel capillary electrophoresis CL method was developed for the determination of Co(Ⅱ)and Cu(Ⅱ).The separation was carried out with a 10 mmol/L sodium acetate solution containing 0.8 mmol/L luminol and 2.0 mmol/Lα-HIBA(adjusted to pH 4.8 by HAc solution).The post-capillary reagent was 2.0 mmol/L K_3Fe(CN)_6 which was adjusted to pH 13.0 by NaOH solution.Under the optimum conditions,the detection limits(S/N=3)for Co(Ⅱ)and Cu(Ⅱ)were 7.5×10~(-11)mol/L and 7.5×10~(-9)mol/L,with the linear range of 7.5×10~(-9)mol/L to 1.0×10~(-6)mol/L and 7.5×10~(-8)mol/L to 5.0×10~(-5)mol/L, respectively.