改进的离子色谱系统监测重庆嘉陵江水质（英文）

The w ater quality monitoring operation to evaluate the w ater quality of polluted river is an extremely im po rtant task fo r the river-w atershed m anagem ent/co ntro l based o n the enviro nm ental po licy.In this study,the no vel,sim ple and co nvenient w ater quality m o nito ring o f Jialing-River in Cho ngqing,China w as carried o ut using an advanced io n chro m ato graphy(IC) co nsisting o f io n-ex clusio n/catio n-ex change chro m ato graphy(IEC/CEC) with conductivity detection for determining simultaneously the common anions such as SO 2 4,Cl,and NO 3 and the catio ns such as Na +,NH + 4,K +,Mg 2 +,and Ca 2 +,the ion-exclusion chromatography(IEC) w ith visible detectio n fo r determ ining sim ultaneo usly the nutrient co m po nents such as pho sphate and silicate io ns,and the IEC w ith the enhanced co nductivity detectio n using a po st co lum n o f K +-fo rm catio n-ex change resin fo r determ ining HCO 3-alkalinity as an ino rganic-carbo n so urce fo r bio m ass synthesis in bio lo gical reactio n pro cess under the aero bic co nditio ns.Acco rding to the io nic balance theo ry betw een the to tal equivalent co ncentratio ns o f anio ns and catio ns,the w ater quality evaluatio n o f the Jialing-River w aters taking at different sam pling sites in Cho ngqing m etro po litan area w as carried o ut using the advanced IC system.As a result,the effectiveness o f this no vel w ater quality m o nito ring m etho do lo gy using the IC system w as dem o nstrated o n the several practical applicatio ns to a typical bio lo gical sew age treatm ent plant o n Jialing-River o f Cho ngqing.     

离子色谱-抑制型电导检测法同时测定食品级润滑油中的3种无机阴离子

建立了离子色谱-抑制型电导检测同时测定食品级润滑油中Cl^-、NO₃^-、SO₄^2- 3种代表性无机阴离子的方法。样品经50%(v/v)甲醇水溶液超声提取,离心后所得下层水相用0.22 μm混合纤维过滤膜净化,以15 mmol/L KOH溶液为淋洗液,采用抑制型电导检测器进行检测,外标法定量。在上述条件下,Cl^-、NO₃^-、SO₄^2- 3种无机阴离子在0.10~20.00 mg/L范围内具有良好的线性关系(R²>0.999);检出限(S/N=3)为0.01~0.03 mg/kg;在1.00、5.00、10.00 mg/kg添加水平下,实际样品中3种阴离子的加标回收率为90.0%~103.6%,相对标准偏差为2.8%~5.7%。结果表明,该方法无需燃烧、灰化油相基质等繁琐耗时的前处理过程,可以快速、准确定量测定食品级润滑油中Cl^-、NO₃^-、SO₄^2- 3种无机阴离子的含量,适用于润滑油等油品中痕量无机阴离子的同时分离与测定。     

Determination of carbon dioxide and acid components in exhaust gas by suppressed ion chromatography.

Although anions are usually determined by suppressed ion chromatography (IC), carbonate and bicarbonate ions can not be determined, because a mixed solution of sodium carbonate and sodium hydrogencarbonate is used as the eluent. This paper describes an IC method for the determination of carbonate ion and common anions using an IonPac AG17/AS17 column, an EG 40 eluent generator and a conductivity detector. The proposed IC method could determine carbonate ion and anions within 6 min. The relative standard deviations (n = 5) for chloride (0.4 mg L(-1)), nitrite (0.8 mg L(-1)), carbonate (100 mg L(-1)), nitrate (1.0 mg L(-1)) and sulfate (2.0 mg L(-1)) ions were 5.1%, 1.1%, 4.2%, 5.1% and 1.1%, respectively. In addition, the absorbing solution of carbon dioxide was examined, and 2-amino-2-methyl-1-propanol was found to be a good absorbing solution. The proposed IC method was applied to the determination of carbon dioxide and acid components in flue gas and automobile exhaust gas.     

Development and validation of analytical methodology using capillary electrophoresis for separation and determination of anions in rainwater

A new capillary electrophoresis (CE) procedure was developed for simultaneous determination of both organic and inorganic anions in rain water using a background electrolyte (BGE) containing 5 mM molybdate, 0.15 mM CTAH, 0.01% PVA and 5 mM Tris buffer to adjust pH at 7.9. Under optimised conditions, good repeatability (RSD for sulphate in migration time=0.36% and peak area=4.2%), low detection limit (2 ppb for chloride) and satisfactory working range (50 ppb-20 ppm for hydrodynamic injection, 10 ppb-3 ppm for electrokinetic injection for chloride) were obtained. The reliability of the CE procedure developed was established by satisfactory recovery tests and good agreement of results obtained by both the CE and ion chromatography (IC) methods. The procedure developed had been successfully applied for field monitoring of rainwater showing good repeatability and capability of detecting trace anions at ppb levels beyond the IC working range. Thus, the new CE procedure developed provides a quick, sensitive, economic and reliable method to meet the need for the simultaneous determination of both organic and inorganic anions in the acid rain monitoring programme.     

Ion chromatographic analysis of anions in ammonium hydroxide,hydrofluoric acid,and slurries,used in semiconductor processing

In this study, ion chromatography (IC) with suppressed conductivity detection was used for the determination of trace anions in 29% (w/w) ammonium hydroxide, 49% (w/w) hydrofluoric acid and slurries. For these samples, various sample pretreatment methods were applied to eliminate matrix interferences. For concentrated ammonium hydroxide, an on-line electrochemical neutralizer (SP10 AutoNeutralization module) was used to neutralize the base prior to the IC analysis. For concentrated hydrofluoric acid, a heart cutting technique with an ion-exclusion column was used to separate the anions of interest prior to an IC separation. A method was also developed to analyze chloride in silica slurries by IC.     

Simultaneous determination of trace amounts of borate, chloride and fluoride in nuclear fuels employing ion chromatography (IC) after their extraction by pyrohydrolysis

An accurate and sensitive method based on the combination of pyrohydrolysis-ion chromatography (PH-IC) is proposed for the simultaneous separation and determination of boron as borate, chloride and fluoride in nuclear fuels such as U(3)O(8), (Pu,U)C and Pu-alloys. The determination is based on the initial pyrohydrolytic extraction of B, Cl and F from the samples as boric acid, HCl and HF, respectively, which are subsequently separated by ion chromatography (IC). The proposed method significantly improves the existing analytical methodology as it combines the determination of boron, a critical trace constituent in nuclear materials, along with F(-) and Cl(-) for chemical quality control measurements. Various experimental parameters were optimized to achieve maximum recoveries of the analytes during the pyrohydrolysis and to get better ion chromatographic (IC) separation of borate, F(-) and Cl(-) along with other anions such as CH(3)COO(-), NO(2)(-), NO(3)(-), Br(-), PO(4)(3-) and SO(4)(2-). Recoveries of more than 93% could be obtained for all the analytes in the sample (0.5-1.5 g) at 1200+/-25K and distilled with pre-heated steam at the flow rate of 0.3 mL/min. An isocratic elution with a mobile phase of 0.56 M d-mannitol in 6.5mM NaHCO(3) was used for the IC separation. The detection limits for B (as borate), F(-) and Cl(-) were 24, 13 and 25 microgL(-1), respectively. Precision of about 5% was achieved for determination of boron, Cl(-) and F(-) in the samples containing 1-5 ppm(w) of boron, and 10-25 ppm(w) of Cl and F. The method was validated with reference materials and successfully applied to the nuclear fuels. The methodology is easy to adapt on routine basis.     

Determination of atmospheric concentrations of inorganic anions by ion chromatography following ultrasonic extraction

The capability of the suppressed conductometric detection ion chromatography (IC) was investigated for the separation and determination of inorganic anions (F-, Cl-, NO3- and SO4(2-)) in standard reference materials SRM-1648 urban particulate matter following ultrasonic extraction. The effects of the cationic surfactant (SDS) and the anionic surfactant (CTAB) on ultrasonic extraction efficiency of inorganic anions from complex matrix of airborne particulate matter were investigated. The results showed that surfactant can enhance the extraction efficiency. Finally, the concentrations of inorganic anions in the atmosphere of the city of Isfahan were determined. The results showed a trend of SO4(2-) > NO3- > Cl- > F-.     

Determination of inorganic anions in biological fluids with direct sample injection by electrostatic ion chromatography using zwitterionic micelles in both stationary and mobile phases

A new ion chromatographic (IC) system, which uses zwitterionic (e.g., Zwittergent 3-14) micelles as both stationary and mobile phases, highly useful for the analysis of inorganic anions in biological samples, was developed. The zwitterionic micellar stationary phase (which is obtained by immobilizing the zwitterionic surfactant on surfaces of the reversed-phase ODS) showed high ability to confine the elution bands of the large amount of SO4(2-) and Cl- to narrow zones. As a result, a base-line separation of NO2-, Br- and NO3- from SO4(2-) and Cl- is always achieved. The zwitterionic micellar mobile phase, (which is obtained by dissolving the zwitterionic surfactant with a suppressive electrolytic solution, e.g., aqueous NaHCO3 solution), on the other hand, showed high ability for rapid elution of proteins. The separation column is therefore always being cleaned up even after the protein-containing sample is directly injected. The zwitterionic micelles are also insensitive to conductivity detection, therefore either the suppressed or the non-suppressed conductivity detection method is applicable for detection of the analyte ions. Urine and serum were chosen as the model real samples and were analysed with direct sample injection; the results of successful determination of a number of inorganic anions (SO4(2-), Cl-, NO2-, Br- and NO3-) in both samples have demonstrated the usefulness of this new IC system.     

Determination of low-molecular-mass aliphatic carboxylic acids and inorganic anions from kraft black liquors by ion chromatography

An ion chromatographic (IC) method with suppressed conductivity detection (CD) was developed and validated for the quantitative determination of several low-molecular-mass aliphatic mono- and dicarboxylic acids as their carboxylate anions together with some inorganic anions (chloride, sulfate, and thiosulfate) from kraft black liquors. To confirm the identification of some carboxylate anions which lack commercial model substances, a qualitative IC method with suppressed electrospray ionization mass spectrometry (ESI-MS) was also developed. The separations were performed on an IonPac AS 11-HC anion-exchange column operated at 25 degrees C within 25 min by a gradient elution with aqueous potassium hydroxide (suppressed CD in the AutoRegen mode) or sodium hydroxide (suppressed ESI-MS in the pressurized bottle mode). In the validation process a mixture of carboxylic acids and inorganic anions in aqueous media and in seven different types of wood and non-wood black liquor samples were quantitatively analyzed by IC-CD. As a result, calibration lines with correlation coefficients of 1.00 for all analytes were achieved at a concentration range from 0.05 to 105 mg L(-1). In black liquor samples intra-day (n=6) precision values ranged from 0.9 to 5%. Day-to-day (n1=3) and intermediate precision values were less than 5% for all other compounds except sulfate and thiosulfate. The variability in the thiosulfate and sulfate results is due in large part to the oxidation of sulfide and thiosulfate, respectively. Recoveries were close to 100% with standard deviations less than 8%. Depending of the analyte, the limits of detection and quantification were, respectively, between 1 and 8 microg L(-1) and between 3 and 27 microg L(-1) for standard compounds in aqueous media and between 6 and 106 microg L(-1) and between 14 and 148 microg L(-1) for black liquor samples. These validation results clearly indicated that with respect to selectivity, linearity, limits of detection and quantification, precision, and accuracy, the IC-CD method showed good applicability in the determinations described above.     

膜处理-离子色谱法测定碳酸钡中的杂质阴离子

建立了一种膜处理-离子交换色谱测定碳酸钡中痕量杂质阴离子(F^-、SO₄^2-和NO₃^-)的方法。碳酸钡是一种难溶于水的固体,因此选用酸对其进行溶解。为了减少酸根离子的影响,利用阳离子膜只能通过阳离子而阻碍阴离子交换的特点,用质量分数为7%的盐酸溶解阳离子交换膜内的碳酸钡样品,稀释100倍,过0.22 μ m滤膜,进样分析,进样体积为25 μ L。经流速为1 mL/min的20 mmol/L KOH淋洗液淋洗,目标离子经过Ion Pac AG11-HC保护柱(50 mm×4 mm)和Ion Pac AS11-HC阴离子交换色谱柱(250 mm×4 mm)进行分离,最后由抑制电导进行检测。在优化的色谱条件下,该方法在0.01~5.00 mg/L范围内线性关系良好,相关系数R²≥0.9996。相对标准偏差(RSD)为1.87%~2.19%,检出限(S/N=3)为1.37~9.45 μ g/L。将该方法应用于实际样品的检测中,得到样品的加标回收率为84.0%~106.2%。该方法实现了固体碳酸钡中杂质阴离子含量的测定,为水不溶性固体物质中的离子检测提供了依据,具有较好的应用前景。     

High Temperature Corrosion Resistance of Coatings Deposited by Hvof for Application in Steam Turbines

The geothermal steam turbines are exposed to mechanisms of corrosion/erosion that weakens its components and reduces their useful life. Due to this problem work has been done in application and characterization of coating in solid state by means of the technique of high-velocity Oxygen Fuel (HVOF), evaluating the corrosion rate (V_corr) at high temperature of MCrAlY and Diamalloy 4006 coatings deposited on stainless steel SS304. Test was performance in an Autoclave at 170 ⁰C using a modified geothermal fluid as electrolyte. Open circuit potential was monitoring during 24 hours until the system reached the equilibrium. After that, Polarization and Impedance Spectroscopy techniques were used to evaluate the specimens. For microstructure characterization; X–ray Diffraction (XRD), electron sweep microscope (SEM) and Optical microscope were applied. Results show that both coatings (Diamalloy 4006 and MCrAlY), have low current density compare with the substrate, which is an indicative of a lower corrosion rate due to the passive behavior of the species deposited on the Surface of the coating.     

离子色谱-抑制电导检测法同时测定草甘膦母液中的含磷副产物及无机阴离子

建立了一种抑制电导检测-离子色谱(IC)同时测定草甘膦生产工艺中母液里的草甘膦及其副产物、无机阴离子的方法。样品经过滤后直接进样,色谱条件: IonPac AS11-HC分离柱(250 mm×4 mm)和IonPac AG11-HC保护柱(50 mm×4 mm),在线淋洗液发生器KOH梯度淋洗,流速1.0 mL/min,采用抑制电导检测。草甘膦、甲基草甘膦、六甲基磷酰三胺(HMPA)、增甘膦、亚磷酸、磷酸、Cl~和SO2~4的线性范围分别为0.1～20 mg/L、0.1～20 mg/L、0.1～50 mg/L、0.25～50 mg/L、0.05～20 mg/L、0.2～50 mg/L、0.02～20 mg/L和0.05～50 mg/L,相关系数分别为0.9995、0.9993、0.9999、0.9998、0.9999、0.9985、0.9999和0.9980,加标回收率为93.7%～104.0%,相对标准偏差均小于2.5% (n=7),检出限(以信噪比(S/N)=3计)为0.002～0.025 mg/L。该方法用于草甘膦生产工艺中母液里草甘膦及其含磷副产物和无机阴离子的测定,结果令人满意。     

Stimuli-responsive polyguanidino-oxanorbornene membrane transporters as multicomponent sensors in complex matrices

We introduce guanidinium-containing synthetic polymers based on polyguanidino-oxanorbornenes (PGONs) as anion transporters in lipid bilayers that can be activated and inactivated by chemical stimulation. According to fluorogenic anion export experiments with vesicles, PGON transporters are most active in neutral bilayers near their phase transition, with EC50's in the nanomolar range. Six times higher effective transporter concentrations were measured with aminonaphthalene-1,3,6-trisulfonate than with 5(6)-carboxyfluorescein, demonstrating the importance of anion binding for transport and excluding nonspecific efflux. Negative surface potentials efficiently annihilate transport activity, while inside-negative membrane potentials slightly increase it. These trends demonstrate the functional importance of counterions to hinder the binding of hydrophilic counterions and to minimize the global positive charge of the transporter-counterion complexes. Strong, nonlinear increases in activity with polymer length reveal a significant polymer effect. Overall, the characteristics of PGONs do not match those of similar systems (for example, polyarginine) and hint toward an interesting mode of action, clearly different from nonspecific leakage caused by detergents. The activity of PGONs increases in the presence of amphiphilic anions such as pyrenebutyrate (EC50 = 70 microM), while several other amphiphilic anions tested were inactive. PGONs are efficiently inactivated by numerous hydrophilic anions including ATP (IC 50 = 150 microM), ADP (IC50 = 460 microM), heparin (IC50 = 1.0 microM), phytate (IC50 = 0.4 microM), and CB hydrazide (IC50 = 26 microM). The compatibility of this broad responsiveness with multicomponent sensing in complex matrices is discussed and illustrated with lactate sensing in sour milk. The PGON lactate sensor operates together with lactate oxidase as a specific signal generator and CB hydrazide as an amplifier for covalent capture of the pyruvate product as CB hydrazone (IC50 = 1.5 microM).     

Identification of homemade inorganic explosives by ion chromatographic analysis of post-blast residues

Anions and cations of interest for the post-blast identification of homemade inorganic explosives were separated and detected by ion chromatographic (IC) methods. The ionic analytes used for identification of explosives in this study comprised 18 anions (acetate, benzoate, bromate, carbonate, chlorate, chloride, chlorite, chromate, cyanate, fluoride, formate, nitrate, nitrite, perchlorate, phosphate, sulfate, thiocyanate and thiosulfate) and 12 cations (ammonium, barium(II), calcium(II), chromium(III), ethylammonium, magnesium(II), manganese(II), methylammonium, potassium(I), sodium(I), strontium(II), and zinc(II)). Two IC separations are presented, using suppressed IC on a Dionex AS20 column with potassium hydroxide as eluent for anions, and non-suppressed IC for cations using a Dionex SCS 1 column with oxalic acid/acetonitrile as eluent. Conductivity detection was used in both cases. Detection limits for anions were in the range 2-27.4ppb, and for cations were in the range 13-115ppb. These methods allowed the explosive residue ions to be identified and separated from background ions likely to be present in the environment. Linearity (over a calibration range of 0.05-50ppm) was evaluated for both methods, with r(2) values ranging from 0.9889 to 1.000. Reproducibility over 10 consecutive injections of a 5ppm standard ranged from 0.01 to 0.22% relative standard deviation (RSD) for retention time and 0.29 to 2.16%RSD for peak area. The anion and cation separations were performed simultaneously by using two Dionex ICS-2000 chromatographs served by a single autoinjector. The efficacy of the developed methods was demonstrated by analysis of residue samples taken from witness plates and soils collected following the controlled detonation of a series of different inorganic homemade explosives. The results obtained were also confirmed by parallel analysis of the same samples by capillary electrophoresis (CE) with excellent agreement being obtained.     

原子转移自由基聚合法制备新型亲水作用色谱固定相及其性能评价

以自制的6.0μm单分散大孔交联聚氯甲基苯乙烯-二乙烯基苯(Poly(4-vinylbenzylchloride-co-divi-nylbenzene),PCMS/DVB)微球为基质和引发剂,CuCl和自行合成的三[(2-二甲基氨基)乙基]胺(Tris[2-(dimeth-ylamino)ethyl]amine,Me6TREN)组成混合催化体系,使4-乙烯基吡啶(4-Vinyl pyridine,4-VP)在甲苯中进行原子转移自由基聚合,制得4-乙烯基吡啶聚合物,单体4-乙烯基吡啶的接枝率为8.55%。将该聚合物与正溴丁烷反应制得新型亲水色谱固定相。在亲水作用色谱模式下,流速1 mL/min,乙腈-水为流动相可分离5种芳胺化合物和4种酚类化合物。在离子交换色谱模式下,6 mmol/L Na2CO3-5.5 mmol/L NaHCO3为淋洗液可分别分离5种无机阴离子和4种短链有机酸。结果表明,此固定相对极性化合物和无机阴离子具有良好的分离性能,是一种性能优异的亲水作用色谱固定相。     

Critical comparison of retention models for the optimisation of the separation of anions in ion chromatography: II. Suppressed anion chromatography using carbonate eluents

Seven theoretical retention models, namely the linear solvent strength model (using the dominant equilibrium approach and competing ion effective charge approach), the dual eluent species model, the Kuwamoto model, the extended dual eluent species model, the multiple species eluent/analyte model and the empirical end-points model, were used to describe the retention behaviour of anions in suppressed ion chromatography (IC). An extensive set of experimental retention data was gathered for 24 anions (fluoride, formate, bromate, chloride, hexanesulfonate, bromide, chlorate, nitrate, iodide, thiocyanate, perchlorate, sulfite, succinate, sulfate, tartrate, selenate, oxalate, tungstate, phthalate, molybdate, chromate, thiosulfate and phosphate) on a Dionex AS4A-SC column using carbonate eluents of varying concentration and HCO₃⁻:CO₃²⁻ ratios. Statistical comparison of the predicted and experimentally obtained retention factors showed that the performance of the theoretical models improved with the complexity of the model. However the empirical model (in which a linear relationship is assumed between the logarithm of retention factor and the logarithm of eluent strength, but the slope is determined empirically) gave the most consistent performance across the widest range of anions. The empirical end-points model was also shown to be the most satisfactory model due to its low knowledge requirements and easy solution. Compared with non-suppressed IC (see Part I), the retention behaviour in suppressed IC was found to be easier to model by all retention models.     

Application of ion chromatography to the determination of inorganic anions in foodstuffs.

A review on the applications of ion chromatography (IC) to the determination of inorganic anions in foodstuffs is presented. The anions were commonly determined in food, i.e., SO3(2-), NO3- and NO2-, and to a lesser extent Cl-, Br-, I-, SO4(2-), IO3-, BrO3- and phosphate, are considered. In comparison with standard methods for the determination of anions in food products, chromatographic methods are rapid, sensitive and precise. They also have the advantage of determining several ions simultaneously. The separation may be achieved by conventional IC, by ion interaction chromatography or by ion exclusion chromatography. IC has also been applied to the determination of Br, I, N and S in foods after oxidation or combustion of samples and conversion into anionic forms.     

In-line respeciation: an ion-exchange ion chromatographic method applied to the separation of degradation products of chemical warfare nerve agents in soil

The natural background of anions encountered when analyzing soil samples by ion chromatography (IC) present significant problems in the separation, detection and quantification of isopropyl methylphosphonic acid (IMPA) and methylphosphonic acid (MPA), the degradation products of sarin, a chemical warfare nerve agent. Using chemically-suppressed IC with conductivity detection, a commercially available ion-exchange column, and an isocratic binary eluent system, IMPA and MPA were determined in aqueous extracts of soil at sub-ppm (μg/g) concentrations without the need for gradient elution or organic solvent eluent modifiers. Common soil anions such as chloride, nitrate, sulfate and phosphate do not interfere with the analysis method due to the composition of the binary eluent allowing for greater mobilization of multivalent anions (e.g., MPA, carbonate, and sulfate) while monovalent anions (e.g., IMPA and nitrate) are relatively unaffected. Carbonate is selectively removed by in-line respeciation to bicarbonate.     

Selective anion sensing by a tris-amide CTV derivative: 1H NMR titration, self-assembled monolayers, and impedance spectroscopy

A hydrogen-bond forming tris(amide) receptor based on cyclotriveratrylene (CTV) was prepared. Self-assembled monolayers (SAMs) of the receptor were formed on gold surfaces. Desorption experiments show a surface coverage of 2.26 x 10(-10) mol/cm(2). (1)H NMR and UV measurements confirm that the receptor exhibits the highest affinity for acetate ions among the anions studied. Electrochemical impedance was used to investigate anion sensing by the SAMs and proved to be an efficient and convenient technique for detecting anions in aqueous solutions. Upon binding acetate anions, the monolayer-modified gold electrodes show a drastic increase of the R(ct) values when Fe(CN)(6)(3-/4-) is used as the redox probe. When the probe was changed to a positively charged one, Ru(NH3)(6)(3+/2+), the R(ct) values decreased monotonically as the acetate concentration was increased, thus confirming the accumulation of negative surface charge upon anion binding. H(2)PO(4-) shows some interference when sensing AcO-. Other monovalent anions such as Cl-, Br-, NO3(-) and HSO4(-) do not bind to the CTV receptor either in solution or on the surfaces.     

Suppressed anion chromatography using mixed zwitter-ionic and carbonate eluents

Effect of mixed eluents which contain zwitterions such as 2-(N-morpholino)ethanesulfonic acid (MES), 3-(N-morpholino)propanesulfonic acid (MOPS), 2-(cyclohexylamino)ethanesulfonic acid (CHES) and 3-(cyclohexylamino)-1-propanesulfonic acid (CAPS) and carbonate for suppressed conductivity ion chromatography (IC) were studied. The retention behaviors of all species were affected with different anion exchange columns when adding some zwitterion into carbonate eluent. The retention time of all species, especially those of strong retetion, was substantially shortened in AS14A column with either Na(2)CO(3)/CHES or Na(2)CO(3)/CAPS as eluent while a general increase in retetion time was noticed in AS9-HC column. Low pH of eluent was achieved when zwitterion was added. Without much changes in the background conductivity after suppressed, CHES could be used as suppressed conductivity ion chromatography eluent for determination of species unstable in strong alkaline, such as determination of phosphate in heteropoly acid (HPA) samples in AS14 column. The mixed eluent could also affect the selectivity when it was applied to the study of simultaneous separation of anions and cations in AS9-HC column by suppressed ion chromatography.