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Method for calibrating EDTA-2Na (Ethylene Diamine Tetraacetic Acid-2Na) during total hardness measurement

A calibration method and a technology of total hardness, applied in the chemical field, can solve problems such as cumbersome process, time-consuming, increased zinc loss, etc., and achieve the effect of fast method

Pending Publication Date: 2020-11-17
代堂刚
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] 7.1.3.5.1 Zinc standard solution in GB / T5750.4-2006: Weigh 0.6 g ~ 0.7 g of pure zinc particles, dissolve in hydrochloric acid solution (1+1), warm on a water bath until completely dissolved, Move it into a volumetric flask, set the volume to 1000 ml, and calculate the concentration of the zinc standard solution; the drawbacks of the above method are still called zinc calibration EDTA-2Na (ethylenediaminetetraacetic acid) in methods such as GB / T5750.4-2006 Disodium), the disadvantage of this method is to weigh the zinc particles on the balance, then add (1+1) hydrochloric acid solution and warm it on the water bath until the zinc particles are completely dissolved. The process is complicated and time-consuming, and there are many steps. Increased loss of zinc in solution

Method used

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  • Method for calibrating EDTA-2Na (Ethylene Diamine Tetraacetic Acid-2Na) during total hardness measurement
  • Method for calibrating EDTA-2Na (Ethylene Diamine Tetraacetic Acid-2Na) during total hardness measurement
  • Method for calibrating EDTA-2Na (Ethylene Diamine Tetraacetic Acid-2Na) during total hardness measurement

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] The known quality control sample concentration is 181±6 mg / L, draw 50.0 mL into a 150 ml Erlenmeyer flask, add a few drops of ammonia to adjust the solution to near neutral, then add 5 ml buffer solution and 5 drops of chrome black T indicator , Immediately titrate with EDTA-2Na standard solution until the solution turns from purple-red to pure blue, and the titer is 9.53 mL. At the same time, a blank test is performed, and the blank EDTA-2Na standard solution is titrated to zero.

[0044] A known =181 mg / L; V=50.0 mL; V 0 =0; V 1 =9.53 mL, substituted into the calculation formula to get =0.0092 mol / L, which is consistent with the calibration result of 0.0091 mol / L using the EDTA-2Na method in GB / T5750.4-2006 in Comparative Example 1, and the relative deviation is 1.09%.

Embodiment 2

[0051] Knowing that the concentration of the total hardness standard solution is 100 mg / L, draw 50.0 mL into a 150 ml Erlenmeyer flask, add a few drops of ammonia to adjust the solution to near neutral, then add 5 ml of buffer solution and 5 drops of chrome black T indicator, Immediately titrate with EDTA-2Na standard solution until the solution turns from purple-red to pure blue, and the titer is 5.42 mL. At the same time, a blank test is performed, and the blank EDTA-2Na standard solution is titrated to zero.

[0052] A known =100 mg / L; V=50.0 mL; V 0 =0; V 1 =5.43 mL, substituting into the calculation formula to get =0.0092 mol / L, which is consistent with the calibration result of 0.0091 mol / L using the EDTA-2Na method in GB / T5750.4-2006 in Comparative Example 2, and the relative deviation is also 1.09%.

Embodiment 3

[0059] The known quality control sample concentration is 181±6 mg / L, draw 50.0 mL into a 150 ml Erlenmeyer flask, add a few drops of ammonia to adjust the solution to nearly neutral, then add 5 ml buffer solution and 5 drops of chrome black T indicator Immediately titrate with EDTA-2Na standard solution until the solution turns from purple-red to pure blue, and the titer is 8.87 mL. At the same time, a blank test is performed, and the blank EDTA-2Na standard solution is titrated to zero.

[0060] A known =181 mg / L; V=50.0 mL; V 0 =0; V 1 =8.87mL, substituting into the calculation formula to get =0.0102mol / L, which is consistent with the calibration result of EDTA-2Na in GB / T5750.4-2006 in Comparative Example 3, which is 0.0100mol / L, and the relative deviation is 2.00%.

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Abstract

The invention discloses a method for calibrating EDTA-2Na (Ethylene Diamine Tetraacetic Acid 2Na) during total hardness measurement, which is used for calibrating the EDTA-2Na by using a total hardness quality control sample or a total hardness standard solution instead of a zinc standard solution, and specifically comprises the steps of titration and calculation. Compared with methods used in GB / T5750.4-2006 and the like, the method adopting the total hardness quality control sample or the standard solution to replace the zinc standard solution is fast, simple and accurate. The calibration result of the previous method using zinc standard solution is small because of more steps and content loss of zinc in the diluting and transferring process. The calibration method provided by the invention can fundamentally solve the problem of large deviation of the determination result caused by zinc content loss, improves the accuracy, is simple in operation method, and can be popularized and applied.

Description

Technical field [0001] The invention belongs to the technical field of chemistry, and specifically relates to a calibration method of EDTA-2Na when measuring the total hardness. Background technique [0002] 7.1.3.5.1 Zinc standard solution in GB / T5750.4-2006: Weigh 0.6 g ~ 0.7 g of pure zinc granules, dissolve them in hydrochloric acid solution (1+1), and warm them on a water bath until they are completely dissolved. Transfer to a volumetric flask, dilute the volume to 1 000 ml, and calculate the concentration of the zinc standard solution; the drawbacks of the above methods are still called zinc calibration EDTA-2Na (ethylenediaminetetraacetic acid) in GB / T5750.4-2006 and other methods Disodium). The disadvantage of this method is to weigh the zinc particles on a balance, and then add (1+1) hydrochloric acid solution to warm the zinc particles on a water bath until the zinc particles are completely dissolved. The process is complicated, time-consuming, and there are many steps....

Claims

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Application Information

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IPC IPC(8): G01N31/16
CPCG01N31/16
Inventor 代堂刚
Owner 代堂刚
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