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% ).     

Extraction chromatographic study of aluminium(III) and mutual separation of aluminium(III), gallium(III), indium(III) and thallium(III) with N-n-octylaniline

A selective method has been developed for extraction chromatographic studies of aluminium(III) and its separation from several metal ions with a chromatographic column containing N-n-octylaniline (liquid anion exchanger) coated on silanized silica gel as a stationary phase. The aluminium(III) was quantitatively extracted with the 0.065 mol/L N-n-octylaninine from 0.013 to 0.05 mol/L sodium succinate at a flow rate of 1.0 mL/min. The extracted metal ion has been recovered by eluting with 25.0 mL of 0.05 mol/L hydrochloric acid and estimated spectrophotometrically with aurintricarboxylic acid. The effects of the acid concentration, the reagent concentration, the flow rate and the eluting agents have been investigated. The log-log plots of distribution coefficient (KdAl(III)) versus N-n-octylaniline concentrationin 0.005 and 0.007 mol/L sodium succinate gave theslopes 0.5 and 0.7 respectively and showed theprobable composition of theextracted species was 1:1 (metal to amine ratio) and the nature of extracted species is [RR''NH2+ Al succinate2-] org. .The extraction of aluminium(III) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Aluminium(III) has been separated from multicomponent mixtures, pharmaceutical samples and synthetic mixtures corresponding to alloys. A scheme for mutual separation of aluminium(III), indium(III), gallium(III) and thallium(III) has been developed by using suitable masking agents. The method is fast, accurate and precise.     

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.     

亲水作用色谱柱与阳离子交换树脂柱结合分离无机离子（英文）

A combination of hydrophilic interaction chromatographic(HILIC) column and a weakly acidic cation-exchange resin(WCX) column was used for simultaneous separation of inorganic anions and cations by ion chromatography(IC).Firstly,the capability of HILIC column for the separation of analyte ions was evaluated under acidic eluent conditions.The columns used were SeQuant ZIC-HILIC(ZIC-HILIC) with a sulfobetaine-zwitterion stationary phase(ZIC-HILIC) and Acclaim HILIC-10 with a diol stationary phase(HILIC-10).When using tartaric acid as the eluent,the HILIC columns indicated strong retentions for anions,based on ion-pair interaction.Especially,HILIC-10 could strongly retain anions compared with ZIC-HILIC.The selectivity for analyte anions of HILIC-10 with 5 mmol/L tartaric acid eluent was in the order of I-> NO-3 > Br-> Cl-> H2PO-4.However,since HILIC-10 could not separate analyte cations,a WCX column(TSKgel Super IC-A/C) was connected after the HILIC column in series.The combination column system of HILIC and WCX columns could successfully separate ten ions(Na+,NH+4,K+,Mg2+,Ca2+,H2PO-4,Cl-,Br-,NO-3 and I-) with elution of 4 mmol/L tartaric acid plus 8 mmol/L 18-crown-6.The relative standard deviations(RSDs) of analyte ions by the system were in the ranges of 0.02%-0.05% in retention times and 0.18%-5.3% in peak areas through three-time successive injections.The limits of detection at signal-to-noise ratio of 3 were 0.24-0.30 μmol/L for the cations and 0.31-1.2 μmol/L for the anions.This system was applied for the simultaneous determination of the cations and the anions in a vegetable juice sample with satisfactory results.     

离子排斥色谱用于厌氧消化处理水中脂肪族羧酸的分析（英文）

The analysis of seven aliphatic carboxylic acids(formic,acetic,propionic,iso-butyric,n-butyric,iso-valeric and n-valeric acid) in anaerobic digestion process waters for biogas production was examined by ion-exclusion chromatography with dilute acidic eluents(benzoic acid,perfluorobutyric acid(PFBA) and sulfuric acid) and non-suppressed conductivity/ultraviolet(UV) detection.The columns used were a styrene/divinylbenzene-based strongly acidic cation-exchange resin column(TSKgel SCX) and a polymethacrylate-based weakly acidic cation-exchange resin column(TSKgel Super IC-A/C).Good separation was performed on the TSKgel SCX in shorter retention times.For the TSKgel Super IC-A/C,peak shape of the acids was sharp and symmetrical in spite of longer retention times.In addition,the mutual separation of the acids was good except for iso-and n-butyric acids.The better separation and good detection was achieved by using the two columns(TSKgel SCX and TSKgel Super IC-A/C connected in series),lower concentrations of PFBA and sulfuric acid as eluents,non-suppressed conductivity detection and UV detection at 210 nm.This analysis was applied to anaerobic digestion process waters.The chromatograms with conductivity detection were relatively simpler compared with those of UV detection.The use of two columns with different selectivities for the aliphatic carboxylic acids and the two detection modes was effective for the determination and identification of the analytes in anaerobic digestion process waters containing complex matrices.     

Separation of strontium from associated elements with selective specific resin and extraction chromatography

In this paper,separation of Sr from associated elements（Na,K,Ca,Mg,and Ba） was carried out using an extraction chromatographic column packed with Sr selective specific resin consisting of an octanol solution of 4,4’（5’）-bis（t-butylcyclohexo）-18-crown-6 sorbed on an inert polymeric support.Using 8.0 mol/L HNO₃ as the eluent,Ba and associated elements were eluted immediately from the column, whereas Sr was strongly retained.The adsorbed Sr could then be stripped from the column as the eluent was changed to 0.05 mol/L HNO₃.Complete Sr/Ba separation was demonstrated to be feasible in that Ba could be washed from the column leaving pure Sr by adequate rinsing with 8.0 mol/L HNO₃. Furthermore,matrix effect could be effectively eliminated and the selectivity of the method was improved.The method was applied for the determination of Sr in the high purity barium carbonate （BaCO₃） product and seawater.The recoveries of Sr in 2 samples were determined to be 93.2%and 109%, respectively.     

反相高效液相色谱法同时测定片剂中的加替沙星与盐酸氨溴索

 A reversed-phase high performance liquid chromatography (HPLC) method was developed, validated, and used for the quantitative determination of gatifloxacin (GA) and ambroxol hydrochloride (AM), from its tablet dosage form. Chromatographic separation was performed on a HiQ Sil C18 column (250 mm×4.6 mm, 5 μm), with a mobile phase comprising of a mixture of 0.01 mol/L potassium dihydrogen orthophosphate buffer and acetonitrile (70∶30, v/v), and pH adjusted to 3 with orthophosphoric acid, at a flow rate of 1 mL/min, with detection at 247 nm. Separation was completed in less than 10 min. As per International Conference on Harmonisation (ICH) guidelines the method was validated for linearity, accuracy, precision, limit of quantitation, limit of detection, and robustness. Linearity of GA was found to be in the range of 10-60 μg/mL and that for AM was found to be 5-30 μg/mL. The correlation coefficients were 0.9996 and 0.9993 for GA and AM respectively. The results of the tablet analysis (n=5) were found to be 99.94% with ±0.25% standard deviation (SD) and 99.98% with±0.36% SD for GA and AM respectively. Percent recovery of GA was found to be 99.92%-100.02% and that of AM was 99.86%-100.16%. The assay experiment shows that the method is free from interference of excipients. This demonstrates that the developed HPLC method is simple, linear, precise, and accurate, and can be conveniently adopted for the routine quality control analysis of the tablet.     

Fabrication of poly(2,6-pyridinedicarboxylic acid)/MWNTs modified electrode for simultaneous determination of guanine and adenine in DNA

The fabrication of poly(2,6-pyridinedicarboxylic acid)/MWNTs modified glass electrode(PPDA/MWNTs/GCE) was proposed and used for individual or simultaneous determination of guanine and adenine.The performances of the PPDA/MWNTs/GCE were characterized with cyclic voltammetry(CV).The modified electrode exhibited enhanced electrocatalytic behavior and good stability for the detection of guanine and adenine.Differential pulse voltammetry(DPV) was used to determine the concentration of guanine,adenine.The detection limit(S/N = 3) for guanine and adenine was 0.045μmol/L and 0.05μmol/L,respectively.The electrochemical method for the measurement of guanine and adenine in calf thymus DNA was also developed with this modified electrode and the result was satisfactory.     

Extraction chromatographic separation of platinum(IV) from real samples and associated elements

 The extraction behavior of platinum(IV) was studied with N-n-octylaniline as a function of different parameters, such as pH, concentrations of weak acids, mineral acids, reagents and elution time. A selective method was developed for the extraction chromatographic studies of platinum(IV) and its separation from several metal ions with N-n-octylaniline (liquid anion exchanger) as a stationary phase on silica gel. The quantitative extraction of platinum(IV) was observed with 0.067 mol/L N-n-octylaniline and 0.015 mol/L ascorbic acid at pH 1.0. Metal ion was stripped from the column with water and determined spectrophotometrically with stannous chloride method. The proposed method is free from the interference of a large number of cations and anions. Platinum(IV) was separated from pharmaceutical preparations, alloys and synthetic mixtures. Mutual separation scheme was developed for platinum(IV), palladium(II) and gold(III). The log-log plot of N-n-octylaniline concentration versus the distribution ratio indicates that the probable extracted species is ［RR′NH+2 ］· Pt(C6H7O6)－3.     

基于纳米结构的电化学传感器用于伏安法测定苄丝肼、尿酸和叶酸(英文)

A carbon paste electrode modified with carbon nanotubes and ferrocene was fabricated.An electrochemical study of the modified electrode and an investigation into its efficiency for the electrocatalytic oxidation of benserazide,uric acid and folic acid were undertaken.The electrode was also used to study the electrocatalytic oxidation of benserazide using cyclic voltammetry,chronoamperometry,and square wave voltammetry(SWV).We found that the oxidation of benserazide at the surface of the modified electrode occurs at a potential about 285 mV lower than that of unmodified carbon paste electrode.SWV gave a linear dynamic range from 8.0×10-7 to 7.0×10 4 mol/L.The detection limit was 1.0×10-7 mol/L for benserazide.This modified electrode was used for the determination of benserazide,uric acid,and folic acid in an urine sample.     

强碱阴离子交换树脂及碱性洗脱剂的离子排阻/阴离子交换色谱法同时测定NH4+ ，NO2-和NO3-（英文）

Ion-exclusion/anion-exchange chromatography(IEC/AEC) on a combination of a strongly basic anion-exchange resin in the OH——form with basic eluent has been developed.The separation mechanism is based on the ion-exclusion/penetration effect for cations and the anion-exchange effect for anions to anion-exchange resin phase.This system is useful for simultaneous separation and determination of ammonium ion(NH+4),nitrite ion(NO-2),and nitrate ion(NO-3) in water samples.The resolution of analyte ions can be manipulated by changing the concentration of base in eluent on a polystyrene-divinylbenzene based strongly basic anion-exchange resin column.In this study,several separation columns,which consisted of different particle sizes,different functional groups and different anion-exchange capacities,were compared.As the results,the separation column with the smaller anion-exchange capacity(TSKgel Super IC-Anion) showed well-resolved separation of cations and anions.In the optimization of the basic eluent,lithium hydroxide(LiOH) was used as the eluent and the optimal concentration was concluded to be 2 mmol/L,considering the resolution of analyte ions and the whole retention times.In the optimal conditions,the relative standard deviations of the peak areas and the retention times of NH+4,NO-2,and NO-3 ranged 1.28%-3.57% and 0.54%-1.55%,respectively.The limits of detection at signal-to-noise of 3 were 4.10 μmol/L for NH+4,1.87 μmol/L for NO-2 and 2.83 μmol/L for NO-3.     

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.     

STUDY OF THE FLUORESCENCE ENHANCEMENT IN THE SYSTEM OF EUROPIUM-OR SAMAR-IUM-TERBIUM-DIBENZOYLMETHANE-CETYLTRIMETHYLAMMONIUM BROMIDE-TRITON X-100 AND ITS APPLICATION

A fluorescence enhancement phenomenon on adding terbium to the Eu or Sm-DBM-CTMAB-Triton X-100 fluorescence system was observed. The fluorescence intensity of this system was 50 times greater than that of the system without terbium at pH 9.0. The fluorescence intensity is a linear function of the concentration of europium or samarium in the range of 1.0×10~(-10)-8.0×10~(-6) mol/L and 1.0×10~(-7)-8.0×10~(-6) mol/L, respectively. The deteetion limits for them were 1.0×10~(-12) mol/L and 1.0×10~(-9) mol/L, respectively. This system was used for the determination of europium or samarium in rare earth samples with satisfactory results.     

Determination of chloride ion by electrochemiluminescence and investigation of the mechanism

The electrochemiluminescence (ECL) of luminol in aqueous alkaline solution was studied.Trace amounts of chloride showed significant effect on the efficiency of light emission of luminol as a posi-tive trigonometrical wave pulse was exerted on the solution. The detection limit for the chloride is5.0 ×10~(-6) mol/L and the linear calibration range extends up to 1.0 ×10~(-2) mol/L; the relative standarddeviation for 1.0 ×10~(-5) mol / L chloride is 5%. The influencing factors for chloride determination arealso discussed. The possible mechanism for the electrochemiluminescence reaction may be due to theoxidation of chloride ion in the solution to ClO~-, and the latter acts on luminol and then gives outluminescence. The method has been applied to determine the total chloride in tap water with satisfactoryresults.     

Electroanalysis and simultaneous determination of dopamine and epinephrine at poly(isonicotinic acid)-modified carbon paste electrode in the presence of ascorbic acid

A carbon paste electrode modified with electropolymerized fills of isonicotinic acid was developed.The modified electrode shows excellent electrocatalytic activity toward the oxidation of both dopamine(DA)and epinephrine(EP).Separation of the reduction peak potentials for dopamine and epinephrine was about 357 mV in pH 5.3 phosphate buffer solution(PBS)and the character was used for the detection DA and EP simultaneously.The peak currents increase linearly with DA and EP concentration over the range of 8.0×10-5 to 7.0×10-4 mol/L and 5.0×10-6 to 1.0×10-4 mol/L with detection limits of 2 × 10-5 and 1×10-6 mol/L,respectively.The interference studies showed that the modified electrode exhibits excellent selectivity in the presence of large excess of ascorbic acid(AA).     

Determination of uric acid in human urine by ion chromatography with conductivity detector

A simple,fast,precise and eco-friendly analytical method for the determination of uric acid(UA) in human urine by ion chromatography(IC) was established.The sample pretreatment was not required,only needed centrifugation and filtration.The separation was carried out on a cation exchange column with 2.0 mmol/L nitric acid as mobile phase at the flow-rate 1.0 mL/min.A non-suppressed conductivity detector was used.The IC analysis time for one run was within 10 min under the optimized IC condition.The detection limits were 0.5μg/L(S/N = 3) for uric acid.The recovery was 100.1%while the relative standard deviation (RSD) was 1.8%from 10 measurements.     

悬浮固化液相微萃取-高效液相色谱法测定人血浆和尿样中的卡巴咪嗪（英文）

Solidified floating organic drop microextraction(SFODME)in combination with high performance liquid chromatography was used for separation/preconcentration and determination of carbamazepine(CBZ)in human plasma and urine samples.Parameters that affect the extraction efficiency such as the type and volume of extraction solvent,ionic strength,sodium hydroxide concentration,stirring rate,sample volume and extraction time,were investigated and optimized.Under the optimum conditions(extraction solvent,40μL of 1-undecanol;sodium hydroxide concentration,1 mol/L;temperature,50℃;stirring speed,400 r/min;sample volume,8 mL;sodium chloride concentration,3%(w/v)and extraction time,60 min)the calibration curve was found to be linear in the mass concentration range of 0.4-700.0μg/L.The limit of detection(LOD)was 0.1μg/L and the relative standard deviation(RSD)for six replicate extraction and determination of carbamazepine at 100μg/L level was found to be 4.1%.The method was successfully applied to the determination of CBZ in human plasma and urine samples.     

Selective extraction and preconcentration of cerium(IV) in water samples by cloud point extraction and determination by inductively coupled plasma optical emission spectrometry

Cloud point extraction (CPE) was used for the selective extraction and separation of cerium(IV) from aqueous solutions. The method is based on the formation of cerium(IV)-n-p-tolylbenzohydroxamic acid (n-TBHA) complex that is extracted into the micellar phase (Triton X-114) at a temperature above the cloud point temperature (CPT). After phase separation, the surfactant rich phase was diluted up to 1.0 mL and determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). Under the optimum extraction conditions and instrument parameters, by preconcentration of only 10.0 mL of sample in the presence of 0.09% Triton X-114, an enhancement factor of 13.8 was obtained. The analytical curve was linear in the range of 1.5–1200 μg L⁻¹ and the detection limit was 0.4 μg L⁻¹. The method was applied to the determination of Ce(IV) in water samples with satisfactory results.     

ClO3--SO32--Rh6G-SDBS体系的化学发光及其用于亚硫酸根测定

Based on the micelle synergism mechanism, a chemiluminescence （CL） flow system for the determination of sulfite was described. The CL signal generated from the reaction of chlorate with sulfite in acidic solution was very weak, while the interfusion of sodium dodecylbenzenesulfonate （SDBS） resulted in a highly chemiluminescent intensity. The major goal of this work was to investigate and develop the SDBS rnicelle synergetic CL system. The mechanism was proposed and proved by spectrometry. The results indicated that the unique structure of SDBS micelles prorooted the aggregation of rhodamine 6G （Rh6G） and a much easier energy transfer, leading to a marked shift to red in the CL emission. This CL system was developed for the determination of sulfite and the concentration of sulfite was proportional to the CL intensity in the range of 5.0× 10^-8--1.0× 10^-5 mol/L with the detection limit of 1.7×10^-8 mol/L （S/N=3）. The relative standard deviation was 3.3% for 1.0×10^ 6 mol/L sulfite solution with eleven repeated measurements. This method was successfully applied to the determination of sulfite in powder sugar.     

Fabrication of CeO2 Nanoparticle Modified Glassy Carbon Electrode for Ultrasensitive Determination of Trace Amounts of Uric Acid in Urine

The preparation of a glassy carbon electrode modified by CeO2 nanoparticles was described, which was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. In pH 6.0 buffer, the CeO2 nanoparticle modified electrode （CeO2 NP/GC） gave an excellent electrocatalytic activity for the oxidation of uric acid （UA）. The catalytic current of UA versus its concentration had a good linear relation in the range of 2.0 × 10^-7-5.0 × 10^- 4 mol/L, with the correlation coefficient of 0.9986 and detection limit of 1.0 ×10^-7 mol/L. The modified electrode can be used for the determination of UA in urine, which can tolerate the interference of ascorbic acid up to 1000-fold. The method was simple, quick and sensitive.