Abstract: The ion chromatograph (lC) has been proposed by H. Small and others for nearly 30 years since 1975. It is itself a type of liquid chromatography. Due to its wide application, it has gradually become an independent large class. The basic analysis process of ion chromatography is that the sample passes through the separation column to separate the measured ions. In the suppression ion chromatography, it also passes through the suppression column (device) to reduce the background conductivity of the eluent, and finally is detected by the detector. Ion chromatography can accurately and quickly detect a variety of ions at the same time, which is a major breakthrough in water environment monitoring. It quickly becomes an important analysis method for anions and cations in water and is widely used in water environment monitoring. In this paper, the principles and applications of complex analysis of inorganic anions and cations in water environment monitoring by ion chromatography are reviewed. 1 Characteristics of ion chromatography method (1) Fast and convenient: for 7 common anions CF-, Cl-, Br-, N03-, N02-, S042-, P043-) and six common cations (Li +, (Na +, NH4 +, K +, Mg2 +, Ca2 +) analysis time is less than 20m blood. If an efficient separation column is used to analyze the above seven common anions It will also be greatly shortened. (2) High sensitivity: the concentration range of ion chromatography analysis is μg / L-mg / L. When the injection volume is 50μ, the detection limit of common anions is less than 10μg / L. For example, increase the injection volume and use a small-bore column. mm diameter) or online concentration, the detection limit can reach 10-12g / L. (3) Good selectivity: The selectivity of inorganic and organic anions and cations analyzed by IC method is mainly achieved by selecting appropriate separation and detection systems. Due to the selectivity of the IC, the sample pretreatment requirements are simple, generally only dilution and filtration are required. (4) Multiple ionic compounds can be measured at the same time. Compared with the photometric method and atomic absorption method, the main advantage of IC is that it can detect multiple components in the sample at the same time in a short time. (5) The separation column has good stability and high capacity. Among the IC, styrene / divinylbenzene polymer is the most widely used packing. The high pH stability of this resin allows the use of strong acids or bases as the eluent, which is beneficial for expanding the range of applications. During sample analysis, dissolution, dilution and filtration are the main tasks of pretreatment. 2 Composition and separation method of ion chromatography system The composition of the IC system is mainly composed of four parts: mobile phase transfer part, separation column, detector and data processing unit (see Figure 1 ion chromatography analysis system). Among them, the chromatographic separation column is one of the most important components of ion chromatography. For the suppression type detector, the suppressor is the key component. The high suppression solution and low dead volume can automatically and continuously work without the use of harmful chemical reagents. It is the main feature of modern suppressors. The choice of ion chromatography detector is mainly based on the nature of the ion to be measured and the type of eluent. The same substance can sometimes be detected with multiple detectors, but the sensitivity is different. The ion chromatography anion and cation simultaneous separation technology mainly includes: using a dual flow system, cations are converted into complex anions and analyzed together with inorganic anions, amphoteric ion exchangers are used as the stationary phase, anion and cation mixed bed stationary phases, anion and cation groups The organic molecule coated stationary phase, column switching technology (anion and cation exchange columns in parallel), and anion and cation exchange columns are connected in series. Application of 3 ion chromatography in the field of water environment monitoring Main monitoring substances: inorganic anions and cations, small molecules and acid. Main separation modes: ion exchange, ion exclusion. Main samples: rivers, rivers, lakes, drinking water, groundwater, wastewater, rainwater, power plant circulating water, etc. The application of ion chromatography has penetrated into all aspects of water environment monitoring. Applications range from the analysis of common anions, cations and organic acids in water to the analysis of polar compounds, amino acids, sugars, heavy metals and transition metals and different oxidation states. As an effective trace analysis method, due to its simplicity, high efficiency, high sensitivity and good reproducibility, ion chromatography has replaced traditional chemical analysis methods in many aspects of the water environment, in drinking water, high-purity water and hydrology. Ion chromatography has been widely used in formation. In terms of water quality analysis, ion chromatography can eliminate 13 common anions and cations CF-, Cl-, Br-, N03-, N02-, S042-, P043-, Li +, In addition to the rapid analysis of Na +, NH4 +, K +, Mg2 +, and Ca2 +), the disinfection by-products that have been included in the mandatory drinking water test item of the US EPA (domestic standards are under development) are: Chlorate, oxalate, oxalate, etc. can be accurately quantified; at the same time, it can also analyze oxides, Ming, silica, and some heavy metal organic acids. 3.1 Analysis of inorganic anions and cations Ion chromatography has completely changed the analytical chemistry of common inorganic anions such as F-, Cl-, Br-, NO-2, NO-3, P03-4, and S02-4. The analysis time of these seven anions has been from the 20th century In the 1970s, the 25min was shortened to only 7min. From the separation of 7 kinds of ions in one injection with equal concentration to the gradient elution, the separation of 36 anions in 30min in one injection has become the current determination of anions in drinking water. The best way. In chemically suppressed ion chromatography, it is a mature method to separate Li +, NH + 4, Na +, K +, Ca2 +, Mg2 +, Sr2 +, and Ba2 + using hydrochloric acid and dimer propionic acid (DAP for short) as eluents. The cation exchange stationary phase used in the suppression IC is a cation exchange latex with sulfonic acid groups polymerized on the surface of the styrene / divinyl polymer. The affinity of alkaline earth metal ions is much greater than that of alkali metal ions. It is quite difficult to rinse and separate these two groups of ions at the same time. The Ion-PacCSll cation separation column newly introduced by Dionex Corporation of the United States changes its selectivity by changing the functional group of the cation exchange position or the density of the ion exchange position. It can be rinsed with equal concentration, one-time injection, separating alkali metal and alkaline earth metal ions within 15 minutes. In recent years, the gradient elution technology has developed rapidly. This method is used for the separation of alkali metal and alkaline earth metal ions, and the effect is very good. 3.2 Analysis of organic acids and alkalis Ion chromatography is also an effective method for analyzing organic acids. Some acid-controlling and polybasic acids with control group substituents, such as oxalic acid, tartaric acid, lactic acid, and succinic acid, are difficult to generate volatile components that can be analyzed by gas chromatography through derivatization Has been determined by this method. A new ion repelling column packing contains not only the strong cation exchange group (S03, but also the weak cation exchange group (COOH) in the general repulsion column, which replaces the weak ions of the OH group on the acid molecule with the filler. The co group at the exchange position forms a hydrogen bond, which increases the selectivity for the separation of piperic acid. Mou Shifen et al. Studied ion-exclusion chromatography for the determination of 50 water-soluble organic acids and found the quantitative analysis conditions for 36 organic acids , And used in the analysis of a variety of samples to get satisfactory results. 3.3 Analysis of complex samples With the continuous development of ion chromatography, it is expected that anions and cations and ionic and nonionic substances can be separated at the same time. Ding Mingyu serially connected the anion exchange column before the cation exchange column, and successfully achieved the simultaneous separation of organic acids, inorganic anions and cations. Some water-like components are often more complex, and sometimes even contain inorganic anions, cations and organic substances. It is difficult to determine these components simultaneously. Yu Zhang et al. Simultaneously determined the content of Cl-, Ca2 + and oxalic acid in water samples by single-column anion chromatography. Using EDTA solution as the eluent, Ca2 + reacts with the eluent to form the anionic complex CaEDTA2-. Simultaneous determination of anions, cations and organic acids on a Shim-Pack column. 4 Progress in the field of water environment monitoring by ion chromatography After years of application, ion chromatography has gradually been accepted by domestic and foreign analysis fields, and has been determined as a standard analysis method or a recommended method by some internationally influential institutions. It is a promising analytical method. The main performance of Metrohm732 ion chromatograph: (1) The eluent that needs to be used in large amounts in the analysis can be prepared by itself in the experiment, and the running cost is low. No manufacturer-specific eluent is needed, and there is no need to update the eluent generation system every year. (2) The service life of the IC's core component regeneration suppressor can reach 7-8 years. It has stable performance in organic solvents and has strong adaptability to higher pressures and metals. (3) The measurement range of the conductivity detector is larger 0-1000um / cm. (4) Both anions and cations can be measured and have high sensitivity, which can reach ppt level. (5) The mobile phase delivery pump is a double-piston pump, which has a smooth and good accuracy and precision. The analysis is reproducible and the sensitivity can reach ppt level. (6) No external gas source is needed to increase the injection pressure. Since the advent of ion chromatography, it has been one of the fastest growing analytical methods in the field of analytical chemistry. Before the 1980s, ion chromatography was limited to the analysis of simple inorganic anions and cations. In recent years, the main shortcomings of ion chromatography stationary phases-the instability of silica fillers to pH and the mismatch of high polymer ion exchange fillers to organic solvents have been overcome. With the introduction of matching polymer ion exchange packing, the application of ion chromatography has changed dramatically. Now ion chromatography can analyze various types of ionic compounds, including the analysis of a variety of polar organic compounds, as well as a variety of complex samples containing large molecules and organic solvents can be directly analyzed. 5 Conclusion Ion chromatography is currently the best method for simultaneous determination of multiple anions in drinking water, and it has the advantages of accuracy, simplicity, and speed. The research on simultaneous determination of anions and cations has also aroused interest. Adding EDTA to the mobile phase can make alkaline earth metal and transition metal ions generate stable complex anions, which can be measured simultaneously with common anions. Simultaneous determination of Cl-, NO-3, S02-4, Na +, NH + 4, K +, Mg2 +, Ca2 + using anion exclusion-cation exchange chromatography. However, to make anions and cations at the same time The analysis has reached the level of practicality and popularization, and there are still many problems to be solved. Zhejiang Shengfa Textiles Printing&Dyeing.,ltd , https://www.chzjsf.com