CN109633077B - Method for determining binding water in paraformaldehyde - Google Patents
Method for determining binding water in paraformaldehyde Download PDFInfo
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- CN109633077B CN109633077B CN201811533646.0A CN201811533646A CN109633077B CN 109633077 B CN109633077 B CN 109633077B CN 201811533646 A CN201811533646 A CN 201811533646A CN 109633077 B CN109633077 B CN 109633077B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/16—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using titration
- G01N31/168—Determining water content by using Karl Fischer reagent
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Abstract
The invention provides a method for determining water combined in paraformaldehyde, which comprises the steps of dissolving paraformaldehyde by using dimethyl sulfoxide as a solvent, then performing moisture determination by using a Karl Fischer moisture tester, weighing dried paraformaldehyde m1(g), adding a dimethyl sulfoxide solvent m2(g), and dissolving to prepare a mixed solution of paraformaldehyde and dimethyl sulfoxide, wherein the mixed solution is marked as a solution A; dripping the Karl Fischer's reagent into a dimethyl sulfoxide solvent to remove water in the dimethyl sulfoxide solvent; then, transferring a proper amount of pure water, calibrating the Karl-Fischer reagent, and measuring the titer of the Karl-Fischer reagent; measuring the moisture of a dimethyl sulfoxide solvent m3(g) by using a Karl Fischer moisture tester; accurately weighing the solution A, measuring the water content of the solution A by using a Karl Fischer water content tester, and consuming a Karl Fischer reagent V2; the bound water x of the paraformaldehyde is:
Description
Technical Field
The invention belongs to the field of chemical detection and analysis, and particularly relates to a method for determining bound water in paraformaldehyde.
Background
Paraformaldehyde is an important organic chemical raw material and is mainly applied to the aspects of pesticides, medicines, resins and the like. Paraformaldehyde is a product formed by dehydrating and polycondensing an aqueous formaldehyde solution. Water in paraformaldehyde exists in two forms: one is free water, referred to as moisture content; one is the chemical structural form as the hemiacetal end group, called bound water. The determination of the water bound in the paraformaldehyde does not have a specified detection method at present, and the invention fills the gap.
Disclosure of Invention
The invention aims to provide a method for determining the bound water in paraformaldehyde.
The purpose of the invention is realized as follows: a method for determining bound water in paraformaldehyde, comprising the steps of:
(1) sample preparation: weighing dried paraformaldehyde m1(g), adding dimethyl sulfoxide solvent m2(g), and dissolving to obtain a mixed solution (solution A) of paraformaldehyde and dimethyl sulfoxide;
(2) calibrating a titrant: dripping the Karl Fischer's reagent into a dimethyl sulfoxide solvent to remove water in the dimethyl sulfoxide solvent; then, transferring a proper amount of pure water, calibrating the Karl-Fischer reagent, and determining the titer (T, mg/mL) of the Karl-Fischer reagent;
(3) and (3) measuring the water content of the solvent: the water content of dimethyl sulfoxide solvent m3(g) (same solvent) was measured using a karl fischer moisture meter, and karl fischer reagent V1(mL) was consumed to calculate solvent water content α solvent:
(4) and (3) measuring the water content of the sample: accurately weighing A m4(g) in the step (1), measuring the water content of the mixed solution (solution A) by using a Karl Fischer water content tester, and consuming a Karl Fischer reagent V2 (mL);
the water content of the solvent m in the m4 mixed solution is as follows:
the bound water x of the paraformaldehyde is:
(5) adding a standard and recovering: and (3) transferring a proper amount of the mixed solution (solution A) of the paraformaldehyde and the dimethyl sulfoxide, adding a certain amount of pure water, performing a standard addition recovery test, and calculating the standard addition recovery rate.
The solvent is dimethyl sulfoxide, and the content of the dimethyl sulfoxide is more than or equal to 99.5 percent.
The dissolving process in the step (1) is as follows: dissolving paraformaldehyde in dimethyl sulfoxide solvent in 40-90 deg.C water bath under sealed heating.
The mass ratio of the paraformaldehyde to the dimethyl sulfoxide solvent in the step (1) is 1:5-1: 10.
The method uses dimethyl sulfoxide as a solvent, dissolves paraformaldehyde under certain conditions, and then uses a Karl Fischer moisture tester to perform moisture measurement. The method is simple and easy to implement, has high accuracy and precision, and the recovery rate of the added standard is 95-105%.
Detailed Description
The invention is further illustrated by the following examples, but is not limited thereto.
A method for determining the binding water in paraformaldehyde, comprising the steps of:
a. sample preparation: vacuum drying paraformaldehyde under reduced pressure, accurately weighing dried paraformaldehyde m 1-5.5186 g (accurate to 0.0001g), adding a dimethyl sulfoxide reagent m 2-43.4341 g, sealing, heating in a water bath at 60 ℃ gently until the mixture is dissolved, wherein the solution is A, and recording the total weight of the solution as 48.9527 g;
b. calibrating a titrant: injecting 20mL of dimethyl sulfoxide solvent into a titration cup, and titrating by using a Karl-reagent special for aldehyde ketone to remove water in the solvent; after the instrument is stabilized, accurately transferring 10 mu L of water, injecting the water into a titration cup, and calibrating the Karl-S reagent to obtain a titer T which is 19.6767 mg/mL;
c. and (3) measuring the water content of the solvent: accurately weighing m3 ═ 4.1859g (accurate to 0.0001g) of dimethyl sulfoxide reagent, adding into a titration cup, titrating to an end point by a Karl Fischer moisture tester, consuming the titrant V1 ═ 0.698mL, and calculating to obtain the moisture of the dimethyl sulfoxide reagent, wherein the alpha solvent is 0.33%
d. And (3) measuring the water content of the sample: weighing 3.4752g of mixed solution A (accurate to 0.0001g) of m4, adding the mixed solution A into a titration cup, titrating the mixed solution A to an end point by using a Karl Fischer moisture meter, consuming 0.909mL of titrant V2, calculating to obtain 0.01018g of solvent moisture m in m4,
so as to calculate the water content of the polyformaldehyde sample to be 1.97 percent,
e. and (3) measuring the water content of the sample: weighing m 4-2-10.0895 g of solution A (accurate to 0.0001g), adding the solution A into a titration cup, titrating the solution to an end point by using a Karl Fischer moisture meter, consuming titrant V2-2-2.623 mL, calculating to obtain m4 solvent moisture m solvent moisture 0.02954g,
so as to calculate the water content of polyformaldehyde sample to be alpha sample which is 1.94%
f. Adding a standard and recovering: 8.1764g of solution A (accurate to 0.0001g) is weighed and added into a titration cup, 20uL of water is transferred and added into the titration cup, the titration is carried out by a Karl Fischer moisture meter until the end point is reached, 3.141mL of titrant is consumed, the water content of the mixed solution is calculated to be 0.756%, and the standard recovery rate is 99.30%. { (3.141 × 19.6767-8.1764 × 0.513% × 1000)/20 × 100 ═ 99.30%, 0.513% mean water content of mixed liquor a,
g. adding a standard and recovering: 5.1100g of solution A (accurate to 0.0001g) is weighed and added into a titration cup, 10uL of water is removed and added into the titration cup, the titration is carried out by a Karl Fischer moisture meter until the end point, 1.842mL of titrant is consumed, the water content of the mixed solution is calculated to be 0.709%, and the standard addition recovery rate is 100.32%. { (1.842 × 19.6767-5.1100 × 0.513% × 1000)/10 × 100 ═ 100.32%, 0.513% was the average water content of mixed liquor a. }. Specific detection results are shown in table 1:
table 1: and (3) detecting results of combined water and added standard recovery in a paraformaldehyde sample:
Claims (4)
1. a method for determining bound water in paraformaldehyde: the method is characterized in that: dimethyl sulfoxide is used as a solvent to dissolve paraformaldehyde, and then a Karl Fischer moisture tester is used for moisture measurement, and the specific operation steps are as follows:
(1) sample preparation: weighing dried paraformaldehyde m1g, adding a dimethyl sulfoxide solvent m2g, and dissolving to obtain a mixed solution of paraformaldehyde and dimethyl sulfoxide, wherein the mixed solution is marked as a solution A;
(2) calibrating a titrant: dripping the Karl Fischer's reagent into a dimethyl sulfoxide solvent to remove water in the dimethyl sulfoxide solvent; then transferring a proper amount of pure water, calibrating the Karl-Fischer reagent, and measuring the titer of the Karl-Fischer reagent, wherein the titer is marked as T, mg/mL;
(3) and (3) measuring the water content of the solvent: measuring the moisture of the dimethyl sulfoxide solvent m3g by using a Karl Fischer moisture tester, consuming a Karl Fischer reagent V1mL, and calculating to obtain a solvent moisture alpha solvent:
(4) and (3) measuring the water content of the sample: accurately weighing the solution A m4g obtained in the step (1), measuring the moisture of the solution A by adopting a Karl Fischer moisture tester, and consuming a Karl Fischer reagent V2 mL;
water content of solvent m4 solution a m solvent water content:
the bound water x of the paraformaldehyde is:
(5) adding a standard and recovering: and (4) transferring a proper amount of the solution A, adding a certain amount of pure water, performing a standard addition recovery test, and calculating the standard addition recovery rate.
2. The method according to claim 1, wherein the binding water in paraformaldehyde is: the solvent is dimethyl sulfoxide, and the content of the dimethyl sulfoxide is more than or equal to 99.5 percent.
3. The method according to claim 1, wherein the binding water in paraformaldehyde is: the dissolving process in the step (1) is as follows: dissolving paraformaldehyde in dimethyl sulfoxide solvent in 40-90 deg.C water bath under sealed heating.
4. The method according to claim 1, wherein the binding water in paraformaldehyde is: the mass ratio of the paraformaldehyde to the dimethyl sulfoxide solvent in the step (1) is 1:5-1: 10.
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Citations (5)
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|---|---|---|---|---|
| EP0075246A1 (en) * | 1981-09-17 | 1983-03-30 | Riedel-De Haen Aktiengesellschaft | Two-component titration substance |
| CN101845130A (en) * | 2010-06-04 | 2010-09-29 | 烟台万华聚氨酯股份有限公司 | Method for preparing paraformaldehyde |
| CN103558335A (en) * | 2013-11-05 | 2014-02-05 | 山东圣泉化工股份有限公司 | Method for determining modified Karl Fischer water |
| CN104048891A (en) * | 2014-06-30 | 2014-09-17 | 湖北三江航天江河化工科技有限公司 | Method for determining content of water in sample in process of preparing composite solid propellant |
| CN108426977A (en) * | 2018-05-31 | 2018-08-21 | 中国神华能源股份有限公司 | The test agent and test method of water content in aldehyde ketone |
-
2018
- 2018-12-14 CN CN201811533646.0A patent/CN109633077B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0075246A1 (en) * | 1981-09-17 | 1983-03-30 | Riedel-De Haen Aktiengesellschaft | Two-component titration substance |
| CN101845130A (en) * | 2010-06-04 | 2010-09-29 | 烟台万华聚氨酯股份有限公司 | Method for preparing paraformaldehyde |
| CN103558335A (en) * | 2013-11-05 | 2014-02-05 | 山东圣泉化工股份有限公司 | Method for determining modified Karl Fischer water |
| CN104048891A (en) * | 2014-06-30 | 2014-09-17 | 湖北三江航天江河化工科技有限公司 | Method for determining content of water in sample in process of preparing composite solid propellant |
| CN108426977A (en) * | 2018-05-31 | 2018-08-21 | 中国神华能源股份有限公司 | The test agent and test method of water content in aldehyde ketone |
Non-Patent Citations (3)
| Title |
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| Efficient, precise and fast water determination by the Karl Fischer titration;Cosimo A. De Caro, et al.;《Food Control》;20010212;第431-436页 * |
| 卡尔·费休法测定水分的样品处理方法;王爱萍等;《理化检验(化学分册)》;20160331;第52卷(第3期);第369-372页 * |
| 微波法合成低聚合度多聚甲醛;林陵等;《石油化工》;20080630;第37卷(第6期);第573-577页 * |
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