This standard specifies the method for determining the total content of calcium and magnesium in dispersant products. This standard is applicable to the determination of the total content of calcium and magnesium in surfactant dispersant products. GB/T 5551-1992 Determination of the total content of calcium and magnesium in surfactant dispersants GB/T5551-1992 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Surfactants
Surface active agents -Method for determinationof total calcium and magnesilum conteat Indispersing agents
GB/T5551.--92
Daishan GB 5551—85
This standard adopts the international standard ISO2482—1973 Industrial sodium oxide—Determination of calcium and magnesium content—EDTA complexometric titration.
1 Subject content and scope of application
This standard specifies the method for determining the total content of calcium and magnesium in dispersant products. This standard is applicable to the determination of the total content of calcium and magnesium in surfactant dispersant products. 2 Reference standards
GB6011
Chemical reagents - Preparation of standard solutions for titration analysis (volume analysis) GB603 Chemical reagents - Preparation of preparations and products used in test methods GB9725 General rules for potentiometric titration of chemical reagents 3 Principle of the method
This method is to prepare a quantitative solution of the sample, use EDTA standard bath solution for complexometric titration in the presence of a masking agent, and use an ion-selective electrode as the indicator electrode to measure the change in electrode potential in the solution. The endpoint is determined based on the sudden change in electrode potential, and the total percentage of calcium and magnesium in the sample is calculated based on the volume of the consumed EDTA standard solution. 4 Reagents and materials
4.1 Laboratory distilled water (GB6682): Grade 3 water; 4.2 Sodium diethyldithiocarbamate (copper reagent) (GB10727); 4.3 Hydrochloric acid (GB622) solution: chemically pure, c(HCI)=0.2mol/L 4. 4 Triethanolamine solution, diluted 1+4 aqueous solution, 4.5 Sodium hydroxide (GB629) solution: chemically pure, 10% (m/m), 4. 6 Disodium ethylenediaminetetraacetic acid (EDTA) (C1.Hu,N,O,Na22H,O) (GB 1401) standard titration solution; c(EDTA)=0.010mol/L, prepared and calibrated according to 4.15 of GB601: 4.7 Hydroxide-ammonium fluoride buffer solution (pH10): prepared according to 4.4.9 of GB603. 5 Instruments and equipment
5.1 Beaker: 150 mL
Approved by the State Bureau of Technical Supervision on December 10, 1992 and implemented on October 1, 1993
5.2 Volumetric flask? 500 mL
5.3 Burette, 10 mL brown acid burette, 5.4 Pipette: 50 mL;
GB/T 5551—92
5.5 Magnetic stirrer, 791 type or similar performance instrument, 5.6 LD-2 type electrode potentiometer or similar performance instrument, with a scale of 0.1 mV, 5.7 PCa-1 type ion selective electrode;
5.8 232 type calomel electrode;
5.9 Stopwatch. bzxZ.net
6 Sample
6.1 Preparation of sample solution
According to the estimated total content of calcium and magnesium, weigh the sample mass specified in Table 1 to an accuracy of 0.001g, place it in a 250mL beaker, dissolve it with distilled water, transfer it to a 500mL volumetric flask, dilute to the scale, shake well, and set aside. Table 1
Expected total calcium and magnesium content in the sample, %(m/m)1. 0～2. 0
0. 5~1. 0
0. 1 ~ 0. 5
6.2 Preparation of test solution
Sample mass
Use a pipette (5.4) to draw 50 mL of the above sample solution (6.1) and place it in a 150 mL beaker. Add 2~-3 drops of hydrochloric acid (4.3), 2~3 drops of triethanolamine (4.4), 1~2 drops of sodium hydroxide solution (4.5), and 0.15~0.20 mL of ammonium hydroxide-ammonium chloride buffer solution (4.7) in sequence. The pH value of the test solution should be 10.0~~10.5. Then add about 50 mg of reagent (4.2) to prepare the test solution. The test solution should be prepared before use. Analysis steps
Put the test solution (6.2) on a magnetic stirrer (5.5), stir slightly, insert the calcium ion selective electrode (5.7) and the calomel electrode (5.8), and connect the two electrode plugs to the electrode potentiometer (5.6). Add EDTA standard titration solution (4.6) drop by drop, and observe the change in electrode potential. When the potential value (volts) begins to increase with each drop of EDTA standard titration solution (4.6), the speed of addition should be slowed down, and 1 drop should be added every 2 minutes until the potential changes little. Record the reading of the burette and the measured potential value after each drop of EDTA standard titration solution (4.6). After each measurement, wash the electrode with steamed water for 3 to 5 times, each time for 3 to 5 minutes. At the same time, do a blank test.
Measure a sample twice in parallel, and take its arithmetic mean as the measurement result. B. Table of analysis results
B.1 Determination of titration end point
Determine the end point in accordance with 6.2.2 of GB9725. 8.2 Calculation of results
The mass percentage of the total amount of calcium and magnesium in the dispersant (calculated as calcium) is calculated according to the following formula: X=VV.)·cX 0. 040 08 ×10 ×m
GB/T5551-92
Wherein: X—mass percentage of the total amount of calcium and magnesium in the dispersant (calculated as calcium), %; V—volume of EDTA standard titration solution consumed by the sample, mL; V. ——The volume of EDTA standard titration solution consumed in blank test, the actual concentration of EDTA standard titration solution used in mLC titration, mol/Lm—The mass of the sample, g;
0. 040 08—The mass of calcium in grams equivalent to 1. 00 mL EDTA standard titration solution [c(EDTA)=1. 000 mol/LJ.
9Allowance difference
The allowance difference of each determination value of this method is shown in Table 2. Table 2
Total content of calcium and magnesium in the sample, %(m/m) 1. 0~2. 0
0. 5~1. 0
Additional remarks:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China, and was under the jurisdiction of Shanghai Dyestuff Research Institute, which was responsible for drafting it. The main editors of this standard were Wu Jinglei and Ling Peijiang. Allowance difference, %(m/m)
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