GB/T 31197-2026Inorganic chemicals for industrial use - Determination of impurity ions - Ion chromatography (English PDF)

5.1 General Rules

5.1.1 Unless otherwise specified, the standard titration solutions, preparations, and products used in the test shall conform to GB/T 601 and GB/T 603. Prepared according to regulations.

5.1.2 Unless otherwise stated, the term "solution" in this document refers to an aqueous solution.

5.1.3 All impurity standard solutions, eluents, inhibitor regeneration solutions, and derivatization reagents used in this document were prepared using analytical grade reagents. The reagents used for the sample should be of analytical grade.

5.1.4 The impurity standard solution should be stored in a cool, dry place. The shelf life of sealed storage is generally 6 months. If turbidity, precipitation, or discoloration occurs, the solution should be removed. If there are any changes, it should be prepared again.

5.1.5 Cyanide standard solution, nitrite ion standard solution, carbonate ion standard solution, chlorate standard solution and chlorite standard solution The prepared solution should be prepared immediately before use.

5.1.6 Diluted impurity standard solutions and mixed diluted standard solutions should be prepared and used immediately. When preparing mixed diluted standard solutions, the mixture should not be mixed with other materials. The resulting precipitates or turbid solutions mix together.

5.2 Water Deionized water with an electrical conductivity (at 25°C) of no more than 0.0055 mS/m (equivalent to a resistivity of no less than

5.3 Impurity Standard Solution Prepare impurity ion standard solutions according to Appendix A, or use certified standard substances.

5.4 Rinsing solution

5.4.1 Basic requirements for rinsing solution Select the rinsing solution according to the following requirements.

a) The fixation of the separation column should not be compromised;

b) Suitable for separating the analyte ions;

c) Suitable for detector detection;

d) When using suppressors and derivative devices, their performance requirements can be met;

e) It can maintain chemical stability for a long time.

5.4.2 Preparation of Eluent The eluent should be degassed after preparation, or it can be prepared using pre-degassed water. The eluent should be stored in a cool, dark place to prevent bacterial or algal growth. Reproduction of the species. Commonly used rinsing solutions are listed in Appendix B.

5.5 Suppressor Regeneration Fluid After continuous use of the suppression device, it should be regenerated using suppression regeneration fluid. Commonly used suppression regeneration fluids include sulfuric acid and hydrogen sulfide. Potassium oxide or sodium hydroxide, tetrabutylammonium hydroxide, lithium chloride. The eluent, suppressor type, and suppressor selection depend on the properties of the sample. To use, select the self-circulating regeneration inhibitor mode, external water mode, or regeneration liquid mode for regeneration.

5.6 Post-column derivatization reagents Commonly used post-column derivatization reagents include metal derivatization reagents, chromate derivatization reagents, and bromate derivatization reagents. The appropriate reagent is selected based on the properties of the analyte ion. Post-column derivatization reaction was carried out using appropriate reagents.

5.7 Microporous Filter Membranes 0.22µm or 0.45µm microporous filter membrane.

6.2.1 Infusion System

6.2.1.1 Storage tank The storage tank should be resistant to the corrosion of the rinsing solution and should not contaminate the rinsing solution. Its material should preferably be high-density polyethylene (HDPE) or polytetrafluoroethylene (PTFE). Borosilicate glass, etc.

6.2.1.2 Degassing device The degassing unit should be able to continuously remove air dissolved in the eluent, providing a stable flow rate and baseline. Common degassing methods for degassing units... See Appendix C for the law.

6.2.1.3 Infusion Pump 6.2.1.3.1 Constant Flow Pump A constant flow pump can uniformly deliver the eluent to the separation system. The constant flow pump should meet the following requirements.

a) Uniform flow rate and high precision;

b) Sufficient infusion pressure;

c) Low pulsating flow velocity;

d) Adjustable flow rate;

e) The connecting parts in contact with the liquid are resistant to the corrosion of the rinsing solution and do not contaminate the rinsing solution;

f) Easy to change the rinsing solution. 6.2.1.3.2 Gradient Pump This includes a control section for using two or more eluents and changing the composition of the eluents over time, as well as a section for ensuring uniform mixing of the solution. Devices. Low-pressure gradient devices with a mixer before a constant flow pump or high-pressure gradient devices with a mixer after multiple constant flow pumps can be used. The device should be able to set a wide range of mixing ratios.

6.2.2 Sample Introduction System A quantitative volume of sample solution can be introduced into the instrument using any of the following methods; an autosampler can be used to sequentially dispense multiple sample solutions. Automatic import.

a) Quantitative loop injection. The sample solution to be tested is filled into the sample solution flow path, and then the sample in the quantitative loop is switched through a six-way valve, etc. The solution can be introduced into the separation system flow path using either a full-volume introduction method or a partial-volume introduction method.

b) Concentrated Injection. The sample solution is introduced into the concentration column, and then the ions enriched in the concentration column are introduced into the separation system through a six-way valve or similar means. Unified flow path. The working principle of the sample introduction system is described in Appendix D.

6.2.3 Separation System

6.2.3.1 Chromatographic column A chromatographic column typically consists of a guard column and a separation column. The guard column is placed before the separation column to prevent contaminants in the sample from directly entering the separation column. Column. The separation column is packed with a stationary phase conforming to the specifications in 6.3.2, and is used to separate the corresponding impurity ions.

Note. Consider whether to install a protective column based on the usage requirements.

6.2.3.2 Column oven The column oven has a volume that can accommodate the chromatographic column and is equipped with temperature control devices to maintain a stable temperature.

6.2.4 Inhibition or Derivative Systems The suppression device should preferably be placed between the separation column and the detector. When using a conductivity detector, the suppression device can be added before the detector to reduce interference. The effluent undergoes pretreatment to achieve higher sensitivity during detection. See Appendix E for the types and working principles of suppressors. Note

1.Using a suppressor can reduce the background conductivity of the eluent, increase the conductivity of the analyte ion, improve the signal-to-noise ratio, and eliminate the effect of counterion peaks on weakly retained ions. Influence. The derivatization device should ideally be located between the separation column and the detector for mixing derivatization reagent solutions, pH adjustment solutions, etc. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) The effluent, mixed with derivatizing reagents, enters a post-column reactor for complete reaction, generating a derivative with light-absorbing groups, which is then subjected to UV-Vis light. A photodetector. The reactor can be heated if necessary. Note

2.Heating can promote a chemical reaction between the analyte ions and the derivatization reagent, which facilitates the measurement by the detector.

6.2.5 Detection System Commonly used detectors in ion chromatography include conductivity detectors, amperometric detectors, and ultraviolet-visible detectors; fluorescence detectors can also be used. Mass spectrometers, inductively coupled plasma mass spectrometry (ICP-MS), etc. The detector is made of a material that is not corroded by the eluent and sample solution. The detector should possess high sensitivity, a wide quantitative detection limit, good selectivity, and reproducibility. Detection principle and application of the detector. See Appendix F for the scope.

6.2.6 Data Processing and Control System A chromatography workstation should include data processing and instrument control functions. The data processing system is used to record or display chromatograms, retention times, peaks, etc. It displays chromatographic parameters such as area, peak height, symmetry factor, and resolution, and also features functions such as multi-spectral comparison, chromatographic thumbnail display, and baseline subtraction. The instrument control system is used to set the instrument operating parameters, control the instrument system, and enable simultaneous sample testing and data analysis.

6.3 Separation Column and Stationary Phase

6.3.1 Separation Column Separation columns are typically made of inert synthetic resin or metals such as stainless steel, and are filled with a stationary phase.

6.3.2 Stationary Phase Ion exchange resins are used as the stationary phase in separation columns; commonly used ion exchange resin stationary phases are listed in Table

1.The separation of ionic components mainly involves... Ion separation can be achieved through three methods. ion exchange, ion repulsion, and ion pairing, either individually or in combination. The substrate of the stationary phase... Functional groups and pore size can affect ion selectivity. A suitable stationary phase separation column can be selected according to the characteristics of the sample to be tested.

7.1 Preparation and pretreatment of sample solutions for determination

7.1.1 A sample solution should be prepared before the determination, and the sample solution should be pretreated before entering the ion chromatograph. Inorganic samples and sample solutions... Commonly used methods for treating liquids are shown in Appendix G.

Note. The purpose of pretreatment is mainly to selectively enrich trace amounts of analyte ions from complex matrices or to selectively remove matrix interferences.

7.1.2 To obtain good precision, attention should be paid to the preparation and storage of the sample solution. When measurement cannot be performed immediately, appropriate... Store in a dark place at 4°C~8°C and take measurements as soon as possible.

7.1.3 The container for holding the sample solution should not adsorb the sample solution or contain any components soluble in the sample solution, and the material should preferably be high-density polyethylene. Resins such as olefins, polytetrafluoroethylene, or polypropylene.

7.1.4 The sample solution used for the determination should be soluble in the eluent and should not react chemically with the eluent.

7.1.5 Dilute and concentrate the sample solution to bring the analyte ion to the appropriate concentration required for the determination.

7.1.6 A standard solution may be added to the sample solution as a method for determining accuracy. Before adding the standard solution, it should be confirmed that it will not affect the accuracy of the determination. This can cause the sample solution to form precipitates or produce chemical reactions that form other compounds.

7.2 Setting of Measurement Conditions In product standards or test method standards, appropriate selections should be made for the test conditions according to the following items.

a) Type and flow rate of the rinsing solution (or gradient rinsing conditions);

b) Sample solution injection volume;

c) Types of chromatographic columns;

d) Column oven temperature;

e) Suppressor type and setting conditions;

f) Detector type and setup conditions;

7.7 Recording of Chromatograms

7.7.1 When using data processing equipment, the parameter values related to data input should be set according to the actual situation, including sampling period and time constant. Number and peak detection parameters. See Appendix I for chromatogram recording instructions.

7.7.2 When using a data processing system, the input should not be too large, and attention should be paid to the saturation of the output.

7.7.3 When using a recorder, the time of introduction should be recorded at the same time as the sample solution is introduced.

7.8 Inspection of the instrument after measurement After the sample measurement is completed, check whether the baseline drift, baseline noise, and overall sensitivity of the instrument system have changed, and whether the analyte in the sample has changed. Whether the amount is within the linear range of the quantitative determination.

8.Qualitative Analysis The determination is performed using a diluted standard solution or a mixture of diluted standard solutions and the sample solution under the same conditions. The results are then compared with the standard solution. The retention time of an unknown component in a sample solution (or spiked sample solution) determines the composition of the unkno...