296 results about "Titration" patented technology

The invention relates to the field of intelligent titration control, and discloses a high-precision intelligent titration control method and system.The method comprises the steps of sample information input and preprocessing planning, sample automatic preprocessing, multi-sensor system calibration and preparation, intelligent titration parameter setting and scheme optimization, and multi-sensor data real-time collection and fusion in the titration process. Titration end point prediction and judgment based on machine learning, result calculation, verification and storage, system self-cleaning, maintenance and state monitoring. Through multi-module collaborative operation and a series of intelligent technical means, the accuracy, the reliability, the automation degree and the adaptability of high-precision titration in each link are comprehensively improved, and the high requirements on the titration precision and the titration efficiency in a complex and diversified chemical analysis scene are met.

The invention belongs to the technical field of physical and chemical analysis, and particularly discloses a high-precision full-automatic titration system and method based on fusion of a spectrum sensor and a PLC, a multi-channel spectrum sensor is adopted to capture fine spectrum characteristics of solution color change in real time, and the flow rate of titration liquid is dynamically adjusted through a PLC embedded PID control algorithm, so that the titration accuracy is improved. The method realizes submilliliter-level precision control, constructs a real-time compensation mechanism in combination with temperature, humidity, pH and other environmental parameters, improves the accuracy and robustness of titration end point judgment, automatically updates an end point judgment threshold and control parameters in combination with an AI self-learning module, realizes self-adaptive adjustment and sustainable evolution of the system, and improves the accuracy and robustness of titration end point judgment. The device has the characteristics of modular structure, high detection precision, high control response and high operation stability.

The invention provides a prospecting exploration method for ion adsorption type rare earth ore, and belongs to the technical field of geological mineral exploration, and the prospecting exploration method comprises the following steps: delineating an ore-forming mother rock area in a working area according to the existing ore points of the ion adsorption type rare earth ore in the working area and in combination with a geochemical exploration abnormal area; delineating a favorable metallogenic landform area in the working area through a GIS space analysis technology; carrying out superposition analysis on the ore-forming mother rock area and the favorable ore-forming landform area, and determining a favorable ore-forming prospective area in the working area through comparison; collecting a sample in the metallogenic distant view area, and verifying whether mineralization abnormity exists in the metallogenic distant view area or not by using a rare earth ion leaching-titration precipitation method; and in an area with mineralization abnormity in the metallogenic distant view area, exploration and evaluation are carried out by arranging Gannan drills in the metallogenic distant view area, the resource quantity of the metallogenic distant view area is calculated, and the prospecting exploration range of the ion adsorption type rare earth ore is determined. According to the method, the metallogenic prospective area can be rapidly delineated in a large range, the working range is reduced, and the efficiency of exploration work is improved.

The invention relates to the technical field of acidic wastewater titrimetric analysis, and discloses an automatic sampling titrimetric analysis method based on a copper smelting acidic wastewater treatment link, which comprises the following steps: collecting waste acid to obtain a waste acid sample; carrying out titration treatment on the waste acid sample to obtain a waste acid sample image after the titration reaction is finished, and carrying out sediment outline extraction on the waste acid sample image to generate sediment coagulation complexity; according to the method, automatic sampling titration is combined with image analysis, precipitation coagulation complexity and arsenic specific hue separation degree are extracted, a precipitation effectiveness index and an arsenic residue risk coefficient are generated through dynamic fusion, arsenic precipitates and other precipitates in similar forms are accurately distinguished by utilizing precipitate contour features and arsenic specific hue in an HSV color space, and the arsenic content is accurately determined. The method has the advantages that spectral signal superposition interference is avoided, and the arsenic residual state can be accurately reflected, so that whether arsenic removal is qualified or not is reliably judged, the accuracy and safety of waste acid treatment are improved, and the quality of water reuse is guaranteed.

The invention discloses a comprehensive circulating water analyzer based on a titrimetric analysis method, and belongs to the technical field of power plant water treatment. The analyzer is composed of a multi-channel titration module, an intelligent temperature control reaction kettle, an optical detection array and a central processing system, and through an integrated electrode-optical composite sensing technology, a dynamic temperature compensation algorithm and a deep learning end point prediction model, the problem that in traditional circulating water detection, the multi-parameter measurement precision is low (the error gt; 2%), the anti-interference capability is poor (the turbidity is gt; the innovation points comprise (1) a three-axis linkage microtitration mechanism (the precision is 0.1 microliter) and an anti-crystallization needle head design are combined to improve the reagent feeding stability by 50%, (2) a double-layer eddy current temperature control reaction system (the temperature control precision is + / -0.1 DEG C) and eliminate the interference of temperature fluctuation on the titration reaction, and (3) a transfer learning-based end point prediction algorithm (error 1t, error 1t, error 1t, error 1t, error 1t, error 1t, error 1t, error 1t, error 1t, error 1t, error 1t, error 1t, error 1t). The device can synchronously detect eight indexes such as pH, Cl, SO, total hardness and the like, supports remote monitoring and automatic dosing of chemicals, is suitable for real-time monitoring of circulating cooling water of a power plant, the detection precision reaches + / -0.3%, and the single detection time is 1t, 2.5 minutes.

The invention discloses a water quality total hardness and calcium and magnesium ion content detection method, which comprises: extracting a water quality sample to be detected, and injecting into a cuvette; taking a color developing reagent, injecting the color developing reagent into the cuvette, blowing, stirring and uniformly mixing to obtain a reaction solution; measuring the initial current i0 of the reaction liquid in the cuvette at the wavelength of 475nm and the initial current I0 of the reaction liquid in the cuvette at the wavelength of 640nm; then titrating, and recording a measured current value and a titration volume while titrating; according to the obtained relation curve of the current and the titration volume under the two wavelengths, obtaining the titration volume corresponding to a titration judgment end point, and substituting the titration volume into the calibration curve to obtain the concentration of total hardness or the content of calcium and magnesium ions in the water sample. The measuring method disclosed by the invention not only has extremely high accuracy and precision, but also can be applied to measurement of total hardness or calcium ions under different indicators at the same time, and the turbidity of a water sample or magnesium hydroxide precipitate generated during calcium ion measurement hardly affects a test result.

The invention discloses a method for measuring a hydrochloric acid tank solution, a neutralizing tank solution and analyzing a standard titration solution by using an automatic potentiometric titrator. The method comprises the following steps: S1, preparing a sample solution; s2, calibrating a sample solution; s3, determining a standard titration solution; selecting a sample solution meeting the requirements, wherein the sample solution is a standard titration solution; s4, titration treatment of hydrochloric acid tank liquid or neutralization tank liquid; accurately dropwise adding a calibrated standard titration solution into the hydrochloric acid tank solution or the neutralization tank solution until a titration end point is reached; and S5, measuring the concentration of the hydrochloric acid tank solution or the neutralization tank solution. The titration result of the potentiometric titration mode is not greatly different from the result of the manual titration mode, the potentiometric titration repeatability is good, the potentiometric titration reminds that the end point is advanced by artificial misjudgment by using an electric signal, and meanwhile, the program assists the calculation operation, so that the operation is simpler.

The invention discloses a constant-temperature environment titration calorimetry device and a test method. The constant-temperature environment titration calorimetry device comprises a constant-temperature temperature control system, a calorimetry system, a titration system and a controller. Wherein the titration system comprises a titration container, a liquid storage container, a third control valve and a fourth control valve, the titration container is communicated with the reaction container, the liquid storage container is communicated with the titration container, the third control valve is arranged between the titration container and the liquid storage container, the fourth control valve is arranged between the titration container and the reaction container, and the liquid storage container is used for storing a sample solution; the titration system is configured as follows: when negative pressure is formed in the titration container, the third control valve is opened, the fourth control valve is closed, and the sample solution in the liquid storage container enters the titration container; when the pressure in the titration container is increased, the third control valve is closed, the fourth control valve is opened, and the sample solution in the titration container is injected into the calorimetric container.

The invention discloses a method for determining the content of hydrogen ions in a chloroplatinic acid solution, and belongs to the technical field of analytical testing. In order to solve the problems that the chloroplatinic acid solution is yellow after being diluted and the manual titration end point is difficult to judge, a potentiometric titration method is adopted, and the end point is determined by measuring electrode potential mutation without depending on indicator color change. The method comprises the steps of test condition preparation, burette calibration, standard solution preparation and calibration, sample treatment and titration, result calculation and the like, a full-automatic potentiometric titrator is selected, the titration volume is controlled within the range of 10-15 mL, and a sodium hydroxide standard solution is used for sample titration after calibration. The relative standard deviation of the determination result is less than 0.5%, the adding standard recovery rate is between 96.3% and 103.1%, and the method has the characteristics of high analysis speed, high accuracy and good stability, is suitable for accurate detection of hydrogen ions in chloroplatinic acid production and quality inspection, and effectively solves the defects of the traditional method.

The invention discloses a process and a system for monitoring chloride ions in circulating cooling water based on an on-line titration mode, and belongs to the field of water quality monitoring of industrial circulating cooling water. According to the process, an automatic sampling module, a titration reaction unit, a photoelectric detection module, a data processing module and a control unit cooperatively work. Circulating cooling water enters the titration reactor through automatic sampling, after an indicator is added, a titration agent is injected into the titration reactor through a peristaltic pump, a photoelectric detector judges a titration end point according to the change of the light transmittance of a solution, and the chloride ion concentration is calculated by combining a standard curve. According to the process, manual operation is replaced by online titration, 24-hour continuous monitoring is realized, turbidity interference is effectively avoided by applying photoelectric detection and a turbidity compensation algorithm, an intelligent cleaning mechanism is arranged, pipeline blockage is prevented, the service life of equipment is prolonged, and the automation level and the monitoring precision of monitoring chloride ions in circulating cooling water are greatly improved.

The invention belongs to the technical field of carbon capture, and particularly relates to a method and a device for measuring the concentration of amine in a carbon capture absorbent. The determination method comprises the following steps: (1) calibrating the consistency of a reference amine solution and a pH meter; (2) judging a potentiometric titration end point; and (3) determining the amine concentration of the carbon capture absorbent. The detection method is simple and feasible, the determination device is simple in structure and convenient to operate, and the concentration of the amine in the online running carbon capture absorbent can be monitored, so that the effective running of the carbon capture device is ensured, and the problem that determination cannot be performed due to the fact that a sample is dark in color and cannot be distinguished at a titration end point in a color indicator method is solved.

The invention relates to the field of chemical testing, in particular to a method for measuring the purity of an acrylonitrile raw material, which comprises the following steps: preparing and calibrating a standard solution, weighing a sample, transferring the sample, carrying out sample titration analysis, carrying out blank titration analysis and calculating a result, thereby obtaining the purity of the acrylonitrile raw material. According to the method, the problems of high cost and overlong detection time of instruments required for detecting the purity of acrylonitrile by a gas chromatographic method are solved, the volatilization loss caused by sample transferring is avoided, the detection efficiency and the test accuracy are improved, and the real purity value of acrylonitrile can be reflected more accurately.

The utility model relates to a full-automatic solid sample sampler for chemical titration, which comprises a conveyor belt, a feeding disc, a manipulator sampling mechanism and a weighing mechanism, sample bottle station grooves are arranged on the feeding disc along the circumferential direction, and the conveyor belt is arranged on one side of the feeding disc. When a certain sample bottle station groove in the feeding disc rotates to correspond to the conveying belt, a sample bottle on the conveying belt exactly enters the certain sample bottle station groove in the feeding disc under the action of power inertia of the conveying belt, and a glass container is placed in the weighing mechanism. Sample bottles conveyed to the sampling position on the feeding disc are conveyed to the position above the glass container through the manipulator sampling mechanism and are fed into the glass container. The full-automatic sampler disclosed by the utility model is simple and convenient to operate and accurate in sampling, does not need human intervention in the whole process, eliminates the problems of manual weighing and sampling, manual recording of sampling values and manual intervention of sampling data in the prior art, simultaneously reduces the labor intensity of staff and personnel allocation, and improves the working efficiency.

The invention discloses a prospecting exploration method for ion adsorption type heavy rare earth ore in middle and low mountainous areas, and belongs to the technical field of geological mineral exploration. According to Y, Dy and Nb abnormity and Y-Nb combination abnormity areas such as water chemical exploration and soil chemical exploration of a working area, high-silicon, potassium-rich, alkali-rich and sphene-rich heavy rare earth secondary mineral mineralization mother rocks are preferably selected, and a favorable mineralization area of the ion adsorption type heavy rare earth ore is delineated by combining characteristic parameters that Y / Ce is greater than 0.9 and Dy / Ce is greater than 0.2; screening south and east-south-east abrupt slope (gradient of about 30 degrees) areas by utilizing a GIS spatial analysis technology, overlapping favorable mineralization areas of the ion adsorption type heavy rare earth ore, and comparing and determining an ion adsorption type heavy rare earth ore prospecting target area in a working area; whether mineralization abnormity exists in the heavy rare earth ore prospecting target area or not is verified by using a manual impact sampling drill and a rare earth ion leaching-titration qualitative analysis method; chemical samples are preliminarily collected, 15 components of ion phases are analyzed, whether heavy rare earth ore bodies exist or not is judged and evaluated, the prospecting exploration range of the ion adsorption type heavy rare earth ore is determined, and the prospecting efficiency of the ion adsorption type heavy rare earth ore is improved. According to the method, the mineralization prospective area of the ion adsorption type heavy rare earth ore can be rapidly delineated in a large range, the prospecting target area is narrowed, and the prospecting efficiency of the ion adsorption type heavy rare earth ore is improved.

The invention discloses an automatic titration analysis method for preventing tin ions from interfering copper ions in a tin plating solution, which comprises the following steps: step 1, sequentially adding deionized water and hydrogen peroxide into the tin plating solution, and stirring to obtain a tin precipitation solution; step 2, adding ammonia water into the tin precipitation solution, and recording a standard titration solution volume V when potential changes suddenly through an automatic titrator; and 3, calculating the concentration C of the copper ions. The copper ion content in the tin plating solution is detected by adopting an automatic titration analysis method, the accuracy is high, the operation is suggested, acetylene gas and open fire operation are not used, potential safety hazards are reduced, the stability and the repeatability are high, meanwhile, hydrogen peroxide is added, divalent tin ions and a standard titration solution are prevented from participating in a complexation reaction, and copper ion concentration detection is prevented from being influenced. The detection accuracy of the copper ion concentration is improved.

The utility model discloses a chemical analysis titration rack and a titration table device, and relates to the technical field of chemical titration analysis equipment. The chemical analysis titration stand and titration stand device comprises a titration stand box body and a box door arranged at the opening end of the titration stand box body, a stepped hole is formed in the middle of the surface of the top of the titration stand box body, and a titration stand surface is arranged in an inner cavity of the stepped hole; a hollow pipe is arranged in the center of the top surface of the titration table top, a burette is arranged on one side of the hollow pipe and connected with the hollow pipe through a stabilizing assembly, and an LED lamp strip is arranged in an inner cavity of the hollow pipe; by means of the technical improvement, interference of external light changes on color changes of a titration end point is avoided, meanwhile, judgment of personnel on the end point is improved, and data of a burette can be observed and read conveniently.

Color quantification of chemical test pads and titration of analytes can be performed under different lighting conditions. In one embodiment, the lighting condition is estimated under which a digital image is captured and utilized to select a set of reference colors from which the quantified color is compared to determine the titration. In another embodiment, a plurality of comparisons are made with different lighting conditions with the result having the highest confidence level being selected to determine the titration.

The invention relates to the field of chemical analysis automation equipment, and discloses an automatic potentiometric titration method which comprises the following steps: before a titration task is started, executing adaptive cleaning and collecting residual spectrum fingerprints of a system; calibrating a titration prediction model in real time by using the fingerprint; performing predictive titration to obtain complete titration data; after the titration is finished, carrying out multi-dimensional analysis on the whole process data, and quantitatively evaluating the pollution risk and the data quality; and finally, dynamically adjusting the cleaning strategy of the next task according to the evaluation result, and adaptively updating the prediction model according to the prediction deviation of the titration. By establishing a closed-loop intelligent working process of cleaning, diagnosis, feedback and learning, the state of the system can be sensed in real time, a cleaning strategy and a prediction model can be dynamically adjusted, the cleaning effect is ensured, self-optimization of the titration process is also realized, the long-term analysis accuracy and the intelligent level of the automatic titration system are improved, and the working efficiency is improved. And the dependence on manual intervention and troubleshooting is reduced.

The invention provides a method for monitoring the acidity of water on line, which comprises the following steps: adding a water sample and a titration indicator into a titration cell, uniformly mixing, measuring the absorbance A background of the water sample mixed with the titration indicator at the wavelength lambda, and taking the absorbance A background as an absorbance background value; titrating the water sample by using a NaOH standard solution as a titrant, and measuring the absorbance A of the water sample at the wavelength lambda in the titration process; taking the moment when the absorbance A is greater than or equal to the absorbance threshold A in the titration process as a titration end point, and obtaining the titration volume of the NaOH standard solution at the titration end point; obtaining the acidity of the water sample based on the titration volume. The method adopts an acid-base indicator titration method to monitor the water acidity and determines the titration end point in combination with the absorbance change of the indicator in the titration process, not only realizes online monitoring of the water acidity, but also is simple and convenient to operate, does not need high-frequency maintenance, can effectively reduce the use cost, improves the water acidity monitoring precision, and is suitable for popularization and application. And application and popularization are facilitated.

The invention relates to a mercury content detection method, and relates to the technical field of mercury detection. According to the mercury content detection method, the to-be-detected sample is preliminarily quantified by using the X-ray spectrometer, the mercury content range of the to-be-detected sample can be quickly obtained, the to-be-detected sample is weighed according to the preliminarily measured mercury content, and the accuracy and reliability of subsequent detection can be guaranteed. By means of constant-temperature water bath heating, it can be guaranteed that a sample to be detected is completely decomposed, meanwhile, a solution in the cover type funnel is poured back into the conical flask, mercury compounds volatilized after heating can be collected, mercury content loss is avoided, and the stability and accuracy of subsequent detection results are further guaranteed. The mercury standard solution is prepared, the inductively coupled plasma emission spectrometer is used for detection, manual titration operation is not needed, the anti-interference capability is good, the mercury content can be accurately measured, and the stability and accuracy of a detection result are effectively guaranteed.

The invention provides a method for monitoring the total hardness of water on line. The method comprises the following steps: S1, adjusting the pH value of a water sample to 10 + / -0.1; s2, taking chrome black T as an indicator, titrating the water sample by adopting an EDTA disodium standard solution, and measuring the absorbance A of the water sample at a specific wavelength in the titration process; s3, determining a titration end point based on the change of the absorbance A, and obtaining the titration volume VEDTA of the EDTA disodium standard solution at the titration end point; and S4, obtaining the total hardness of the water sample based on the titration volume VEDTA. According to the method, the total hardness of water is monitored based on an EDTA titration method, the absorbance of a water sample under different developing conditions is measured by adopting double light sources and double wavelengths in the titration process, and the titration speed is adjusted and the titration end point is judged by utilizing the absorbance, so that the purpose of monitoring the total hardness of water is achieved, and online monitoring of the total hardness of water is realized; and operation is more convenient, cost is lower, and popularization and application are facilitated.

A computer implemented system for performing automated titration testing of water samples in order to calculate certain relevant metrics to ensure that the water at the water sites meets the desired standards. A computing device has an testing module that analyzes and produces reports containing data regarding the metrics for samples that have undergone testing using a separate titration device. The titration device includes an automated mobile carousel that holds multiple samples and a reaction chamber with a receptacle configured to receive fluid from the samples. The titration testing device automatically pumps the sample into a sample container held in place in the reaction chamber and pumps an appropriate amount of titrant depending on the metric being tested for so that different titrants are used depending on the metric and detects when the color change / endpoint occurs. Data is collected and reported to the computing device and titration testing module.

The application belongs to the technical field of analysis and detection, and discloses a method for continuously detecting pH value, sulfuric acid content and zinc ion content of electroplating liquid or conductive roller cleaning liquid. The method comprises the following steps: 1) selecting the "pH" block in "pH / mV" on the potential titrator, setting the instrument parameters, inserting the electrode into the to-be-detected liquid, and reading the pH value displayed by the potential titrator; 2) selecting the "mV" block in "pH / mV" on the potential titrator, selecting the dynamic pH titration mode, setting the instrument parameters, diluting the to-be-detected liquid after the pH value is detected, inserting the electrode into the diluted to-be-detected liquid, and adopting the sodium hydroxide standard solution titration, and ending the titration after two equivalent points appear; and 3) calculating the pH value, sulfuric acid content and zinc ion content of the to-be-detected liquid through a formula. The application can realize the continuous detection of the three indexes by adopting one instrument and one standard titration solution, is simple, fast and high in accuracy, and can effectively reduce the influence of chemical reagents on the health of workers.

A method for determining a parameter includes forming a reaction mixture by adding a volume of a solution to a sample. The solution contains a substance acting as a reaction partner for the analyte, where the reaction partner enters into a chemical reaction with the analyte, forming a reaction product of the analyte. The volume of the solution is adjusted, based on measured values of a physical or chemical measurand which are detected during the addition of the solution in the reaction mixture and whose value depends on the concentration of the analyte or of the substance in the reaction mixture. A titration of the solution to be titrated is subsequently performed from which a quantity of the substance present in the reaction mixture after addition of the volume of the solution is determinable, and a value of the parameter is ascertained using the titration.

The application provides an automatic titration analysis method for measuring the aluminum content in high aluminum alloy, which adopts direct reaction of fluoride with a test solution to realize one-step direct titration, and determines the aluminum content in the range of 2.00% to 100.00%, and comprises the following steps: sample decomposition; precipitation of interfering ions; calibration of sodium fluoride standard solution; calibration of automatic potentiometric titrator; and measurement of the sample to be tested. The application solves the problems of sample pretreatment and how to avoid the influence of interfering ions on the determination of aluminum content. The titration operation, reading and calculation are automatically completed by the instrument, effectively reducing human errors, and the application has the advantages of simple operation, accurate and rapid results, wide application range and the like.

The invention relates to the field of analysis and detection, in particular to a method for detecting the content of chlorine in trimethylaluminum, which comprises the following steps: S1) mixing trimethylaluminum solution to be detected and an alcohol solution of alkali in a protective gas atmosphere to obtain intermediate sample solution; in the alcoholic solution of the alkali, the alkali is selected from at least one of potassium hydroxide or sodium hydroxide, and the alcohol is selected from at least one of methanol or ethanol; and S2) carrying out titration detection on the intermediate sample solution by adopting a silver nitrate solution to obtain the chlorine content in the trimethylaluminum. The detection method provided by the invention is a new detection means added relative to the existing detection means, and the method is simple to operate and good in repeatability. The adding standard recovery rate is 94.80%-109.41%, the accuracy and precision requirements of the method are met, and the stability and reliability of the detection method are verified. According to the method for detecting the chlorine content in the trimethylaluminum, the experimental process is safe and controllable, and the price of required instruments is relatively low.

The invention relates to a method for determining the chelation effect and the chelation rate of a compound amino acid microelement chelate. According to the determination method, the chelation effect and the chelation rate of the compound amino acid microelement chelate are determined through combination of an infrared spectroscopy method, an elemental analysis method and an anhydrous titration method, and the chelation effect comprises an action form and action intensity. The determination method comprises the following steps: weighing a compound amino acid trace metal chelate sample; taking a part of the to-be-detected powder and potassium bromide crystals, grinding together, pressing, measuring the infrared spectrum of the powder, and analyzing the chelation type and strength; taking another part of the to-be-detected powder, measuring the nitrogen content of the to-be-detected powder through an elemental analysis method, and calculating the total amount of amino acids in the sample; taking another part of the to-be-detected powder, removing inorganic salt in the to-be-detected powder, and drying; and dissolving the obtained solid powder, titrating without water, carrying out a blank experiment to eliminate the influence of reducing substances in the solution, and calculating to obtain the chelation rate. The method is simple and easy to operate and high in accuracy.

The invention discloses a method for testing the content of trivalent metal elements in a metal oxide, and belongs to the technical field of chemical analysis. The method comprises the following steps: firstly, reducing trivalent metal elements in a sample into divalent metal elements by using a reducing agent ammonium ferrous sulfate in a strong acid environment, wherein unreacted ammonium ferrous sulfate remains in a system; then, potassium permanganate is adopted for titration of unreacted ammonium ferrous sulfate, the end point is based on the fact that the solution becomes light pink and keeps color fastness for 15 seconds, and meanwhile a blank solution is set to eliminate system background interference; by comparing the difference between the blank titration volume and the sample titration volume and combining the titration concentration and the sample mass, the content of the trivalent metal elements in the sample can be accurately calculated. The method has the advantages of simplicity and convenience in operation, strong anti-interference capability, high detection precision and wide application range, is suitable for various metal oxide material systems, and is particularly suitable for quality control and performance analysis of new energy materials and catalysts.

This invention belongs to the field of analytical chemistry technology, specifically relating to a composite indicator and testing method for determining cadmium content in crude cadmium. The composite indicator comprises xylenol orange, thymol blue, and sodium indigo disulfonate, with a mass ratio of xylenol orange, thymol blue, and sodium indigo disulfonate of 1.0–1.5:0.3–0.6:0.5–1.0. This invention utilizes the ternary compound of xylenol orange, thymol blue, and sodium indigo disulfonate, employing the blue background of sodium indigo disulfonate and the reddish-purple and yellow hues of xylenol orange for optical color adjustment. This transforms the color change at the titration endpoint from the traditional reddish-purple to yellow to a bluedish-purple to yellowish-green, significantly increasing the color difference and creating a clear and sharp color change interface, greatly improving the accuracy and reliability of visual endpoint determination.