In this work, a flow injection analysis (FIA) method for the trace determination of lead, cadmium, nickel and cobalt in natural waters by formation of neutral chelates with ammonium pyrrolidine dithiocarbamate (APDC) ...In this work, a flow injection analysis (FIA) method for the trace determination of lead, cadmium, nickel and cobalt in natural waters by formation of neutral chelates with ammonium pyrrolidine dithiocarbamate (APDC) was developed. The neutral chelates formed was retained in a mini-column packed with Linde type A zeolite (LTA) and type Y Faujasite zeolite (FAU) and then eluted with methyl isobutyl ketone (MIBK) to flame atomic absorption spectrometry (EAA) for its detection. Physicochemical characterization of this zeolite was carried out by Fourier Transform infrared spectroscopy and attenuated total reflectance (FTIR and IR-ATR), scanning electron microscopy and energy dispersive X-ray microanalysis (SEM-EDX) and X-ray power diffraction (XRD). Then, a FIA configuration was used with a column preconcentration system coupled to the detection system at room temperature (22?C). The detection limit and the relative standard deviation for 5 determinations of different solutions of Pb2+, Co2+, Ni2+ and Cd2+ for FAU and LTA zeolite were calculated. The sampling frequency ranged from 18-35 h-1 and preconcentration factors from 21-250 were achieved, for a sample volume of 6 mL using 20 mg of sorbents, indicating a high retention of the analytes on the zeolites material. The recoveries obtained in natural waters samples were close to 100% for all ions metal using synthetic zeolites, confirming the applicability of the method. The isotherm models of Langmuir, Scatchard, Freundlich and Dubinin-Radushkevich were used to study the equilibrium data, indicating that successfully followed the Freundlich and Dubinin-Radushkevich (D-R) isotherms at low metal ion concentration. The Freundlich parameter n varied between 0.35-1.01, whereas D-R isotherm yields the sorption free energy E 8 kJ.mol-1 indicating psysisorption.展开更多
A simple, rapid and sensitive flow injection chemiluminescence （FI-CL） method has been developed for the determination of meloxicam. The method is based on the CL-emitting reaction between meloxicam and potassium pe...A simple, rapid and sensitive flow injection chemiluminescence （FI-CL） method has been developed for the determination of meloxicam. The method is based on the CL-emitting reaction between meloxicam and potassium permanganate in a hydrochloric acid medium, enhanced by formaldehyde （HCHO）. Under optimum conditions, calibration curve over the range of 1.0-20.0μg/mL was obtained. The proposed method was successfully applied to the determination of meloxicam in capsules with no evi- dence of interference from common excipients. The detection limit of this method was 25.6 ng/mL. The relative standard deviation was 2.1% for 10.0 μg/mL meloxicam. The sample throughput was found to be 120 samples/h.展开更多
BACKGROUND Although gastroscopy is a commonly used diagnostic and therapeutic technique,postoperative gastrointestinal dysfunction is prone to occur.Traditional Chinese medicine theory suggests that postoperative gast...BACKGROUND Although gastroscopy is a commonly used diagnostic and therapeutic technique,postoperative gastrointestinal dysfunction is prone to occur.Traditional Chinese medicine theory suggests that postoperative gastrointestinal disorders are related to spleen and stomach weakness.This study hypothesizes that the combination of acupoint application at the Ziwu Liuzhu acupoint and percutaneous acupoint electrical stimulation can promote postoperative gastrointestinal function recovery and alleviate stress reactions.AIM To investigate the effects of acupoint application of Ziwu Liuzhu combined with percutaneous acupoint electrical stimulation on postoperative gastrointestinal function recovery and stress response in patients undergoing gastrointestinal endoscopy surgery.METHODS A total of 120 patients who underwent gastroscopy surgery were selected and treated between October 2024 and January 2025.This study used a stratified block randomization method,and then allocated groups using computer-generated random number sequences(SAS 9.4 software).The groups were divided into two groups:A control group of 60 patients who received routine postoperative intervention measures,and an observation group of 60 patients who received acupuncture point application combined with transcutaneous acupoint electrical CONCLUSION The combination of percutaneous acupoint electrical stimulation in gastroscopy patients has been demonstrated to be both highly safe and effective.The benefits of this approach include the promotion of postoperative gastrointestinal function,the reduction of stress response,the attainment of optimal results,and the enhancement of patient satisfaction.展开更多
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 redu...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.展开更多
A novel flow injection chemiluminescence （CL） method for the determination of ciprofloxacin （CPLX） was reported. The proposed method is based on luminescence produced by KMnO4-Na2S2O4-Tb^3＋-CPLX chemiluminescence...A novel flow injection chemiluminescence （CL） method for the determination of ciprofloxacin （CPLX） was reported. The proposed method is based on luminescence produced by KMnO4-Na2S2O4-Tb^3＋-CPLX chemiluminescence （CL） system. The effects of some critical experimental conditions were discussed and the optimization of working conditions was investigated. The linear dynamic range is 3.00 × 10^-8 - 9.00 × 10^-7 mol ·L-1 and the detection limit for CPLX is 4.40 × 10^-9 mol·L^-1. This method was applied to the determination of CPLX in tablet, urine, and serum samples and the recoveries of real sample analyses were in the range from 110 ± 4 to 104 ± 4.展开更多
A new method for the determination of trace non-rare earth elements in high purity rare earth oxides by ICP-AES with preconcentration on an active carbon-silica gel microcolumn in a flow injection system is described ...A new method for the determination of trace non-rare earth elements in high purity rare earth oxides by ICP-AES with preconcentration on an active carbon-silica gel microcolumn in a flow injection system is described in this paper. Experimental parameters such as pH, flow rate,reagent concentration,length of reaction coil,eluent acidity,etc. were optimized. In the buffer solution of NH3. H2O/NH4Cl at pH 4. 6,Al,Cr,Cu,Fe, Pb, V and Zn can be preconcentrated and then eluted with 4. 5 mol/L nitric acid utilizing stop-flow technique. The enrichment factors were in range of 8. 1￣12. 6 with detection limits of μg/m level ,and the RSD with metals at μg/g level were 2. 3￣5. 0% (n= 7). The method proposed can reduce the matrix interference effectively , and has been applied to the determination of non-rare earth metals atμg/g level in high purity Eu2O3 with satisfactory results.展开更多
A simple flow injection spectrophotometric method is reported for the determination of cysteine,N-acetyl cysteine and glutathione based on the reduction of Fe（Ⅲ）/ferricyanide,the in situ reduced ions are reacted wi...A simple flow injection spectrophotometric method is reported for the determination of cysteine,N-acetyl cysteine and glutathione based on the reduction of Fe（Ⅲ）/ferricyanide,the in situ reduced ions are reacted with unreduced portion of ferricyanide/Fe（Ⅲ） to form soluble Prussian blue,which is monitored at 735 nm.The calibration graphs are linear in the concentration ranges of（1―100）×10-6 mol/L for cysteine and N-acetyl cysteine,and（1―50）×10-6 mol/L for glutathione.The relative standard deviations of 1.8%,2.5% and 1.9% were found for eleven replicate analyses of 5×10-6 mol/L cysteine,N-acetyl cysteine and glutathione.The limits of detection（3σ blank） at 5×10-7 mol/L for cysteine,and 3×10-7 mol/L for N-acetyl cysteine and glutathione were obtained.The proposed method allowed 60 injections/h.The effects of common substances present in pharmaceuticals and human physiological fluids were examined.The method was applied to determining cysteine in pharmaceutical formulations with the recoveries in a range of 97% to 106% and the results obtained are agreed well with labeled values.展开更多
A new chemiluminescence (CL) analytical method for determination of rare earth Ho(Ⅲ) ion is reported. It is based on the quenching effect of Ho(Ⅲ) ion on CL intensity of Luminol H 2O 2 Cr(Ⅲ) system. The detecti...A new chemiluminescence (CL) analytical method for determination of rare earth Ho(Ⅲ) ion is reported. It is based on the quenching effect of Ho(Ⅲ) ion on CL intensity of Luminol H 2O 2 Cr(Ⅲ) system. The detection limit is 3×10 -8 mol/L, the linear range is from 1×10 -7 to 1×10 -4 mol/L; the relative standard deviation is less than 3% (for 2×10 -7 mol/L Ho, n=11). The method was applied to determination of Ho(Ⅲ) in pure samples with satisfactory results.展开更多
A flow injection (FI) micro-column system coupled with high performance liquid chromatography (HPLC) was proposed for the pre-separation and determination of active organic component (ecdysterone) in traditional Chine...A flow injection (FI) micro-column system coupled with high performance liquid chromatography (HPLC) was proposed for the pre-separation and determination of active organic component (ecdysterone) in traditional Chinese medicine, Loulu. The factors influencing separation performance were investigated and optimized. Under the optimal conditions, the contents of ecdysterone in Loulu were determined by HPLC system using MeOH-H_2O (40: 60,V/V) as the mobile phase at a flow rate of 1. 0 mL/min. The calibration curve was linear in the range of 0. 5~ 100 mg/L of ecdysterone concentrations. The detection limit of the analyte was 0. 11mol/L(3) with a precision of 0. 38% RSD (n=7 f c= 10. 0 mg/L). The average recovery of the method was 98. 7%. The proposed method has been applied to determine ecdysterone in practical samples, and the determined values by both external standard method and standard addition method were in good agreement. Compared to the traditional solid extraction method, the system proposed has the advantages of simple procedure, good reproducibility, minimum volume requirement, reduction of matrix interference and low contamination risk.展开更多
A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The ...A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.展开更多
A novel flow-injection irreversible biamperometric method is described for the direct determination of iodide. The method is based on electrochemical oxidation of iodide at the gold electrode and the reduction of perm...A novel flow-injection irreversible biamperometric method is described for the direct determination of iodide. The method is based on electrochemical oxidation of iodide at the gold electrode and the reduction of permanganate at the platinum electrode to form an irreversible biamperometric detection system. Under the applied potential difference of 0 V, in the 0.05 mol/L sulfuric acid, iodidecan be determined over the range 4.00×10^-7-1.00×10^-5 mol/L with a sampling frequency of 120 samples per hour. The detection limit for I- is 3.0×10^-7 mol/L and the RSD for 40 replicate determinations of 4.0×10^-5 mol/L potassium iodide is 1.68%. The new method was applied to the analysis of iodide in table salt with satisfactory results.展开更多
This work reports the single-molecule detection of gossypol by flow injection analysis with chemiluminescence method. The method is based on the reaction of luminol with ferricyanid in sodium hydroxide medium sensitiz...This work reports the single-molecule detection of gossypol by flow injection analysis with chemiluminescence method. The method is based on the reaction of luminol with ferricyanid in sodium hydroxide medium sensitized by gossypol. Under the optimum conditions, the CL intensity is proportional to the concentration of gossypol over the range of 1.11×10^-17-2.78×10^-16 mol/L in acid solution and 8.00×10^-11-7.39×10^-8mol/L in neutral solution with correlation coefficients 0.9983 and 0.9905, respectively. The detection limits is 1.60×10^-18 mol/L （S/N=3）. The proposed method has been applied for the determination of the gossypol in cottonseeds and pharmaceutical formulations with satisfactory results.展开更多
A flow injection irreversible biamperometric method for the determination of chlorogenic acid is described. The proposed method is based on the electrochemical oxidation of chlorogenic acid at pretreated platinum elec...A flow injection irreversible biamperometric method for the determination of chlorogenic acid is described. The proposed method is based on the electrochemical oxidation of chlorogenic acid at pretreated platinum electrode and the reduction of permanganate at another electrode to form an irreversible biamperometric detection system. Under the external potential difference （z^v） of 0 V, in the 0.05 mol/L sulfuric acid, chlorogenic acid can be determined over the range 0.8-120 mg/L with a sample measurement frequency of 80 samples/h. The detection limit is 0.18 mg/L. The proposed method exhibits the satisfactory reproducibility with a relative standard derivation （R.S.D.） of 2.21% for 19 successive determinations of 40 mg/L.展开更多
A novel, simple, rapid, sensitive and highly selective flow injection procedure for the spectrophotometric determination of chlorine dioxide in the presence of other chlorine species, viz,free chlorine, chlorite, chlo...A novel, simple, rapid, sensitive and highly selective flow injection procedure for the spectrophotometric determination of chlorine dioxide in the presence of other chlorine species, viz,free chlorine, chlorite, chlorate and hypochlorite, is developed. The method is based on the discoloration reaction between chlorine dioxide and chlorophenol red and can overcome the shortcomings existed in direct spectrophotometric determination for chlorine dioxide owing to the serious interference of free and combined chlorine. The procedure gave a linear calibration graph over the range 0—0.71 mg/L of chlorine dioxide. With a detection limit of 0.024 mg/L and a sample throughput of 60 samples/h.展开更多
Poly（pheniothiazine） films were prepared on a porous carbon felt（CF） electrode surface by an electrooxidative polymerization of three phenothiazine derivatives（i.e.,Tthionine（TN）,Toluidine Blue（TB） and Methyl...Poly（pheniothiazine） films were prepared on a porous carbon felt（CF） electrode surface by an electrooxidative polymerization of three phenothiazine derivatives（i.e.,Tthionine（TN）,Toluidine Blue（TB） and Methylene Blue（MB）） from 0.1 mol/L phosphate buffer solution（pH 7.0）.Among the three phenothiazies,the poly（TB） film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form（NADH） at ＋0.2 V vs.Ag/AgCl.The poly（TB） film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH.The peak currents（peak heights） were almost unchanged,irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min,resulting in the measurement of NADH（ca.30 samples/hr） at 4.1 mL/min.The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 μmol/L（sensitivity：0.318 μA/（μmol/L）;correlation coefficient：0.997）.The lower detection limit was found to be 0.3 μmol/L（S/N = 3）.展开更多
The chemiluminescence reactions between lucigenin and reductants such as Mo(LII),V( II), U(III), W(III), Cr(II), Ti(III) and Fe( II), which were produced on-line by passing Mo(VI),V(V),U(VI), W(VI), Cr(VI,III),Ti(IV) ...The chemiluminescence reactions between lucigenin and reductants such as Mo(LII),V( II), U(III), W(III), Cr(II), Ti(III) and Fe( II), which were produced on-line by passing Mo(VI),V(V),U(VI), W(VI), Cr(VI,III),Ti(IV) and Fe(III) through a micro Jones column, are studied in detail. Results show that the reactions can be used directly for the determination of these substances. The mechanism of the reactions is also investigated.展开更多
An adsorbent calix[4]arene carboxylic acid was employed as the adsorption material for on-line flow in jection(FI)micro-column preconcentration coupled with flame atomic absorption spectrometry(FAAS)determination of t...An adsorbent calix[4]arene carboxylic acid was employed as the adsorption material for on-line flow in jection(FI)micro-column preconcentration coupled with flame atomic absorption spectrometry(FAAS)determination of trace heavy metals(Cu,Pb,Co,Ni and Cd).Parameters such as the pH,loading time and flow rate of sample,and the concentration,volume and flow rate of eluent were optimized.The enrichment factors are 50.0,56.5,11.6,12.1 and 19.1 for Cu,Pb,Co,Ni,and Cd,respectively,and a sample throughput of 20 h–1 was obtained.The limits of de tection for Cu,Pb,Co,Ni,and Cd were in a range of 1.56―3.91μg/L,and the relative standard deviations(RSDs)were less than 2.76%(n=7).Furthermore,the proposed method was successfully applied to the determination of Cu,Pb,Co,Ni,and Cd in certified reference materials and various water samples.展开更多
A simple and sensitive flow injection（FI） spectrophotometric method was reported for the determination of uric acid based on the reduction of Fe（III）/ferricyanide in the presence of uric acid. The in situ reduced ...A simple and sensitive flow injection（FI） spectrophotometric method was reported for the determination of uric acid based on the reduction of Fe（III）/ferricyanide in the presence of uric acid. The in situ reduced ions reacted with unreduced portion of ferricyanide/Fe（III） to form soluble Prussian blue, which was monitored at an absorption wavelength of 735 nm. The optimized conditions allow a linear calibration graph in a concentration range of 1―100 μmol/L. The relative standard deviation was in a range of 0.5%―2.5%, with a detection limit（3σ blank） of 0.3 μmol/L and a sampling frequency of 60 injection/h was obtained. The effect of common substances present in human physiological fluids on the determination of uric acid was examined. The method was applied to determining uric acid in human urine samples with the recoveries in a range of 96%―105%. The results agree well with those by spectrophotometric reference method at a confidence level of 95%. Spectrophotometric procedures for uric acid determination in clinical samples were reviewed briefly.展开更多
Combined with flow-injection (FI) technology, a simple chemiluminescence (CL) method was developed for hydrazine determination in this paper. It was found that hydrazine could greatly decrease the strong CL signal pro...Combined with flow-injection (FI) technology, a simple chemiluminescence (CL) method was developed for hydrazine determination in this paper. It was found that hydrazine could greatly decrease the strong CL signal produced by the reaction between luminol and hexacyanoferrate (III) in alkaline medium. The decreased CL intensity was linear with hydrazine concentration in the range of 5.0×10-9 g·mL-1 to 4.0×10-5 g·mL-1, and the limit of detection was 2.0×10-9 g·mL-1 (3σ) with a relative standard deviation of 2.4~4.1% (n=5).展开更多
基金The authors are grateful to the FondoNacional de Ciencia y Tecnología(FONACIT)and Consejo de Desarrol-loCientífico,Humanístico,Tecnológico y de lasArtes(CDCHTA)for financial support,Proyects S1-97001192 and C-133105-08B respectively,Laboratorio de Análisis Químico Estructural de Materiales(LAQUEM)and La-boratorio de Cristalografía of the Universidad de Los Andes(ULA)Mérida-Venezuela.
文摘In this work, a flow injection analysis (FIA) method for the trace determination of lead, cadmium, nickel and cobalt in natural waters by formation of neutral chelates with ammonium pyrrolidine dithiocarbamate (APDC) was developed. The neutral chelates formed was retained in a mini-column packed with Linde type A zeolite (LTA) and type Y Faujasite zeolite (FAU) and then eluted with methyl isobutyl ketone (MIBK) to flame atomic absorption spectrometry (EAA) for its detection. Physicochemical characterization of this zeolite was carried out by Fourier Transform infrared spectroscopy and attenuated total reflectance (FTIR and IR-ATR), scanning electron microscopy and energy dispersive X-ray microanalysis (SEM-EDX) and X-ray power diffraction (XRD). Then, a FIA configuration was used with a column preconcentration system coupled to the detection system at room temperature (22?C). The detection limit and the relative standard deviation for 5 determinations of different solutions of Pb2+, Co2+, Ni2+ and Cd2+ for FAU and LTA zeolite were calculated. The sampling frequency ranged from 18-35 h-1 and preconcentration factors from 21-250 were achieved, for a sample volume of 6 mL using 20 mg of sorbents, indicating a high retention of the analytes on the zeolites material. The recoveries obtained in natural waters samples were close to 100% for all ions metal using synthetic zeolites, confirming the applicability of the method. The isotherm models of Langmuir, Scatchard, Freundlich and Dubinin-Radushkevich were used to study the equilibrium data, indicating that successfully followed the Freundlich and Dubinin-Radushkevich (D-R) isotherms at low metal ion concentration. The Freundlich parameter n varied between 0.35-1.01, whereas D-R isotherm yields the sorption free energy E 8 kJ.mol-1 indicating psysisorption.
文摘A simple, rapid and sensitive flow injection chemiluminescence （FI-CL） method has been developed for the determination of meloxicam. The method is based on the CL-emitting reaction between meloxicam and potassium permanganate in a hydrochloric acid medium, enhanced by formaldehyde （HCHO）. Under optimum conditions, calibration curve over the range of 1.0-20.0μg/mL was obtained. The proposed method was successfully applied to the determination of meloxicam in capsules with no evi- dence of interference from common excipients. The detection limit of this method was 25.6 ng/mL. The relative standard deviation was 2.1% for 10.0 μg/mL meloxicam. The sample throughput was found to be 120 samples/h.
基金Supported by Zhejiang Province Traditional Chinese Medicine Science and Technology Plan Project,No.2023ZL230。
文摘BACKGROUND Although gastroscopy is a commonly used diagnostic and therapeutic technique,postoperative gastrointestinal dysfunction is prone to occur.Traditional Chinese medicine theory suggests that postoperative gastrointestinal disorders are related to spleen and stomach weakness.This study hypothesizes that the combination of acupoint application at the Ziwu Liuzhu acupoint and percutaneous acupoint electrical stimulation can promote postoperative gastrointestinal function recovery and alleviate stress reactions.AIM To investigate the effects of acupoint application of Ziwu Liuzhu combined with percutaneous acupoint electrical stimulation on postoperative gastrointestinal function recovery and stress response in patients undergoing gastrointestinal endoscopy surgery.METHODS A total of 120 patients who underwent gastroscopy surgery were selected and treated between October 2024 and January 2025.This study used a stratified block randomization method,and then allocated groups using computer-generated random number sequences(SAS 9.4 software).The groups were divided into two groups:A control group of 60 patients who received routine postoperative intervention measures,and an observation group of 60 patients who received acupuncture point application combined with transcutaneous acupoint electrical CONCLUSION The combination of percutaneous acupoint electrical stimulation in gastroscopy patients has been demonstrated to be both highly safe and effective.The benefits of this approach include the promotion of postoperative gastrointestinal function,the reduction of stress response,the attainment of optimal results,and the enhancement of patient satisfaction.
文摘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.
文摘A novel flow injection chemiluminescence （CL） method for the determination of ciprofloxacin （CPLX） was reported. The proposed method is based on luminescence produced by KMnO4-Na2S2O4-Tb^3＋-CPLX chemiluminescence （CL） system. The effects of some critical experimental conditions were discussed and the optimization of working conditions was investigated. The linear dynamic range is 3.00 × 10^-8 - 9.00 × 10^-7 mol ·L-1 and the detection limit for CPLX is 4.40 × 10^-9 mol·L^-1. This method was applied to the determination of CPLX in tablet, urine, and serum samples and the recoveries of real sample analyses were in the range from 110 ± 4 to 104 ± 4.
文摘A new method for the determination of trace non-rare earth elements in high purity rare earth oxides by ICP-AES with preconcentration on an active carbon-silica gel microcolumn in a flow injection system is described in this paper. Experimental parameters such as pH, flow rate,reagent concentration,length of reaction coil,eluent acidity,etc. were optimized. In the buffer solution of NH3. H2O/NH4Cl at pH 4. 6,Al,Cr,Cu,Fe, Pb, V and Zn can be preconcentrated and then eluted with 4. 5 mol/L nitric acid utilizing stop-flow technique. The enrichment factors were in range of 8. 1￣12. 6 with detection limits of μg/m level ,and the RSD with metals at μg/g level were 2. 3￣5. 0% (n= 7). The method proposed can reduce the matrix interference effectively , and has been applied to the determination of non-rare earth metals atμg/g level in high purity Eu2O3 with satisfactory results.
文摘A simple flow injection spectrophotometric method is reported for the determination of cysteine,N-acetyl cysteine and glutathione based on the reduction of Fe（Ⅲ）/ferricyanide,the in situ reduced ions are reacted with unreduced portion of ferricyanide/Fe（Ⅲ） to form soluble Prussian blue,which is monitored at 735 nm.The calibration graphs are linear in the concentration ranges of（1―100）×10-6 mol/L for cysteine and N-acetyl cysteine,and（1―50）×10-6 mol/L for glutathione.The relative standard deviations of 1.8%,2.5% and 1.9% were found for eleven replicate analyses of 5×10-6 mol/L cysteine,N-acetyl cysteine and glutathione.The limits of detection（3σ blank） at 5×10-7 mol/L for cysteine,and 3×10-7 mol/L for N-acetyl cysteine and glutathione were obtained.The proposed method allowed 60 injections/h.The effects of common substances present in pharmaceuticals and human physiological fluids were examined.The method was applied to determining cysteine in pharmaceutical formulations with the recoveries in a range of 97% to 106% and the results obtained are agreed well with labeled values.
文摘A new chemiluminescence (CL) analytical method for determination of rare earth Ho(Ⅲ) ion is reported. It is based on the quenching effect of Ho(Ⅲ) ion on CL intensity of Luminol H 2O 2 Cr(Ⅲ) system. The detection limit is 3×10 -8 mol/L, the linear range is from 1×10 -7 to 1×10 -4 mol/L; the relative standard deviation is less than 3% (for 2×10 -7 mol/L Ho, n=11). The method was applied to determination of Ho(Ⅲ) in pure samples with satisfactory results.
基金Education Ministy Foundation for Chinese Returned Scholars and Nature Science Foundation of Hubeiprovince!98J054
文摘A flow injection (FI) micro-column system coupled with high performance liquid chromatography (HPLC) was proposed for the pre-separation and determination of active organic component (ecdysterone) in traditional Chinese medicine, Loulu. The factors influencing separation performance were investigated and optimized. Under the optimal conditions, the contents of ecdysterone in Loulu were determined by HPLC system using MeOH-H_2O (40: 60,V/V) as the mobile phase at a flow rate of 1. 0 mL/min. The calibration curve was linear in the range of 0. 5~ 100 mg/L of ecdysterone concentrations. The detection limit of the analyte was 0. 11mol/L(3) with a precision of 0. 38% RSD (n=7 f c= 10. 0 mg/L). The average recovery of the method was 98. 7%. The proposed method has been applied to determine ecdysterone in practical samples, and the determined values by both external standard method and standard addition method were in good agreement. Compared to the traditional solid extraction method, the system proposed has the advantages of simple procedure, good reproducibility, minimum volume requirement, reduction of matrix interference and low contamination risk.
基金This study was supported by the National Natural Science Foundation of China
文摘A stopped-flow reversed flow injection method for the determination of free cyanide is proposed. Pyridine-barbituric acid mixture is injected in the flow system as reagent to form the colour species with cyanide. The flow is stopped when the reagent zone comes in the flow cell, where absorbance-time data are collected at 580nm wavelength. The linear range of the determination is 0.1 -10μg/ml CN-. The sampling rate is 60h-1 and the relative standard deviation is 1.6% (n=16) at 5.0 μg/ml CN-1 level. With satisfactory results, the proposed method was applied to the determination of free cyanide in wastewater without sample pretreatment.
基金support of the Guangxi Science Fund For Youth(No.0135003)Guangxi Universities One Hundred Young-middle Scholar Fund for the present work.
文摘A novel flow-injection irreversible biamperometric method is described for the direct determination of iodide. The method is based on electrochemical oxidation of iodide at the gold electrode and the reduction of permanganate at the platinum electrode to form an irreversible biamperometric detection system. Under the applied potential difference of 0 V, in the 0.05 mol/L sulfuric acid, iodidecan be determined over the range 4.00×10^-7-1.00×10^-5 mol/L with a sampling frequency of 120 samples per hour. The detection limit for I- is 3.0×10^-7 mol/L and the RSD for 40 replicate determinations of 4.0×10^-5 mol/L potassium iodide is 1.68%. The new method was applied to the analysis of iodide in table salt with satisfactory results.
基金financial support from the National Natural Science Foundation of China(Grant No.20075017)and from Tianjin Normal University.
文摘This work reports the single-molecule detection of gossypol by flow injection analysis with chemiluminescence method. The method is based on the reaction of luminol with ferricyanid in sodium hydroxide medium sensitized by gossypol. Under the optimum conditions, the CL intensity is proportional to the concentration of gossypol over the range of 1.11×10^-17-2.78×10^-16 mol/L in acid solution and 8.00×10^-11-7.39×10^-8mol/L in neutral solution with correlation coefficients 0.9983 and 0.9905, respectively. The detection limits is 1.60×10^-18 mol/L （S/N=3）. The proposed method has been applied for the determination of the gossypol in cottonseeds and pharmaceutical formulations with satisfactory results.
基金the National Natural Science Foundation of China （No. 20665001） Guangxi Science Fund （No. 0640029） Innovation Project of Guangxi Graduate Education （No. 2006105930502m33）.
文摘A flow injection irreversible biamperometric method for the determination of chlorogenic acid is described. The proposed method is based on the electrochemical oxidation of chlorogenic acid at pretreated platinum electrode and the reduction of permanganate at another electrode to form an irreversible biamperometric detection system. Under the external potential difference （z^v） of 0 V, in the 0.05 mol/L sulfuric acid, chlorogenic acid can be determined over the range 0.8-120 mg/L with a sample measurement frequency of 80 samples/h. The detection limit is 0.18 mg/L. The proposed method exhibits the satisfactory reproducibility with a relative standard derivation （R.S.D.） of 2.21% for 19 successive determinations of 40 mg/L.
文摘A novel, simple, rapid, sensitive and highly selective flow injection procedure for the spectrophotometric determination of chlorine dioxide in the presence of other chlorine species, viz,free chlorine, chlorite, chlorate and hypochlorite, is developed. The method is based on the discoloration reaction between chlorine dioxide and chlorophenol red and can overcome the shortcomings existed in direct spectrophotometric determination for chlorine dioxide owing to the serious interference of free and combined chlorine. The procedure gave a linear calibration graph over the range 0—0.71 mg/L of chlorine dioxide. With a detection limit of 0.024 mg/L and a sample throughput of 60 samples/h.
基金financially supported in part by the Open Research Center Project of the Ministry of Education,Science and Culture of Japan
文摘Poly（pheniothiazine） films were prepared on a porous carbon felt（CF） electrode surface by an electrooxidative polymerization of three phenothiazine derivatives（i.e.,Tthionine（TN）,Toluidine Blue（TB） and Methylene Blue（MB）） from 0.1 mol/L phosphate buffer solution（pH 7.0）.Among the three phenothiazies,the poly（TB） film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form（NADH） at ＋0.2 V vs.Ag/AgCl.The poly（TB） film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH.The peak currents（peak heights） were almost unchanged,irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min,resulting in the measurement of NADH（ca.30 samples/hr） at 4.1 mL/min.The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 μmol/L（sensitivity：0.318 μA/（μmol/L）;correlation coefficient：0.997）.The lower detection limit was found to be 0.3 μmol/L（S/N = 3）.
文摘The chemiluminescence reactions between lucigenin and reductants such as Mo(LII),V( II), U(III), W(III), Cr(II), Ti(III) and Fe( II), which were produced on-line by passing Mo(VI),V(V),U(VI), W(VI), Cr(VI,III),Ti(IV) and Fe(III) through a micro Jones column, are studied in detail. Results show that the reactions can be used directly for the determination of these substances. The mechanism of the reactions is also investigated.
基金Supported by the Fund of State Key Laboratory of Rare Earth Resource Utilization,Changchun Institute of Applied Chemi-stry,Chinese Academy of Sciences(No.RERU2011006)
文摘An adsorbent calix[4]arene carboxylic acid was employed as the adsorption material for on-line flow in jection(FI)micro-column preconcentration coupled with flame atomic absorption spectrometry(FAAS)determination of trace heavy metals(Cu,Pb,Co,Ni and Cd).Parameters such as the pH,loading time and flow rate of sample,and the concentration,volume and flow rate of eluent were optimized.The enrichment factors are 50.0,56.5,11.6,12.1 and 19.1 for Cu,Pb,Co,Ni,and Cd,respectively,and a sample throughput of 20 h–1 was obtained.The limits of de tection for Cu,Pb,Co,Ni,and Cd were in a range of 1.56―3.91μg/L,and the relative standard deviations(RSDs)were less than 2.76%(n=7).Furthermore,the proposed method was successfully applied to the determination of Cu,Pb,Co,Ni,and Cd in certified reference materials and various water samples.
基金Supported by the CIIT-Project Funded by COMSATS Institute of Information Technology,Pakistan
文摘A simple and sensitive flow injection（FI） spectrophotometric method was reported for the determination of uric acid based on the reduction of Fe（III）/ferricyanide in the presence of uric acid. The in situ reduced ions reacted with unreduced portion of ferricyanide/Fe（III） to form soluble Prussian blue, which was monitored at an absorption wavelength of 735 nm. The optimized conditions allow a linear calibration graph in a concentration range of 1―100 μmol/L. The relative standard deviation was in a range of 0.5%―2.5%, with a detection limit（3σ blank） of 0.3 μmol/L and a sampling frequency of 60 injection/h was obtained. The effect of common substances present in human physiological fluids on the determination of uric acid was examined. The method was applied to determining uric acid in human urine samples with the recoveries in a range of 96%―105%. The results agree well with those by spectrophotometric reference method at a confidence level of 95%. Spectrophotometric procedures for uric acid determination in clinical samples were reviewed briefly.
文摘Combined with flow-injection (FI) technology, a simple chemiluminescence (CL) method was developed for hydrazine determination in this paper. It was found that hydrazine could greatly decrease the strong CL signal produced by the reaction between luminol and hexacyanoferrate (III) in alkaline medium. The decreased CL intensity was linear with hydrazine concentration in the range of 5.0×10-9 g·mL-1 to 4.0×10-5 g·mL-1, and the limit of detection was 2.0×10-9 g·mL-1 (3σ) with a relative standard deviation of 2.4~4.1% (n=5).
