CN102944554A - Rapid paraformaldehyde content measuring method - Google Patents

Abstract

The invention relates to a rapid paraformaldehyde content measuring method which is characterized by comprising the following steps of: weighting 0.0001g of paraformaldehyde samples and putting the paraformaldehyde samples in a conical flask; adding a sodium hydroxide solution and then adding a hydrogen peroxide solution till the reaction is complete; cooling to room temperature; adding a bromothymol blue indicating liquid; and titrating with a sulfuric acid standard volumetric solution until the solution becomes cyan, wherein the reaction temperature is room temperature. According to the rapid paraformaldehyde content measuring method, the paraformaldehyde content is measured by a acid-base titration method at the room temperature; and the rapid paraformaldehyde content measuring method has the advantages of simplicity, rapidness, high accuracy, high precision and good reproducibility.

Description

The rapid assay methods of paraformaldehyde content

Technical field

The present invention relates to organic compound content assay method field, particularly a kind of rapid assay methods of paraformaldehyde content.

Background technology

Paraformaldehyde is important organic industry raw material, is widely used in the aspects such as synthetic resin, bonding agent, medicine.Domestic production and the producer that uses paraformaldehyde adopt sulphite process or iodimetric titration usually to the mensuration of paraformaldehyde content, although this assay method is classical, operation intermediate link influence factor is more, time-consuming, easily produces error.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, provide a kind of simple, quick, accuracy is high, precision is high, under the room temperature of favorable reproducibility with the method for determination of acid-basetitration industry paraformaldehyde content.

The present invention realizes that the technical scheme of purpose is as follows:

A kind of rapid assay methods of paraformaldehyde content, step is as follows:

Take by weighing the paraformaldehyde sample, be accurate to 0.0001g, place conical flask, add sodium hydroxide solution, add again superoxol to reacting completely, be cooled to room temperature, add the bromthymol blue indicator solution, be titrated to solution with the sulfuric acid standard titration solution and become blue-green, temperature of reaction is room temperature;

Paraformaldehyde content X% is calculated as follows:

$X=\frac{(V_0-V)C\×3.003}{m}\×100$

In the formula:

The content of X-paraformaldehyde, in formaldehyde, %;

The concentration of C-sulfuric acid standard titration solution, mol/L;

The volume of the sulfuric acid standard titration solution that V-titration sample consumes, ml;

V ₀The volume of the sulfuric acid standard titration solution that-titration blank consumes, ml;

3.003-with 1.00ml sulfuric acid standard titration solution C(1/2H ₂SO ₄)=1mol/L, g;

The quality of m-sample, g.

Advantage of the present invention and beneficial effect are:

Paraformaldehyde content of the present invention adopts acid base titration under the room temperature, method has simply, fast, accuracy is high, precision is high, the advantage of favorable reproducibility.

Embodiment

Below in conjunction with embodiment, following embodiment is illustrative, is not determinate, can not limit protection scope of the present invention with following embodiment.

Take by weighing the paraformaldehyde sample, be accurate to 0.0001g, place conical flask, add sodium hydroxide solution, add again superoxol to reacting completely, be cooled to room temperature, add the bromthymol blue indicator solution, be titrated to solution with the sulfuric acid standard titration solution and become blue-green.Do simultaneously blank test.Temperature of reaction is room temperature, need not heating water bath.

Paraformaldehyde content X% is calculated as follows:

$X=\frac{(V_0-V)C\×3.003}{m}\×100$

In the formula:

The content of X-paraformaldehyde (in formaldehyde), %;

The concentration of C-sulfuric acid standard titration solution, mol/L;

The volume of the sulfuric acid standard titration solution that V-titration sample consumes, ml;

V ₀The volume of the sulfuric acid standard titration solution that-titration blank consumes, ml;

3.003-with 1.00ml sulfuric acid standard titration solution (C(1/2H ₂SO ₄)=1mol/L) (quite to restrain the quality of the formaldehyde that represents, g;

The quality of m-sample, g.

Test philosophy:

Paraformaldehyde generates sodium formate with the superoxol reaction in excessive sodium hydroxide solution, and then instead drips excessive sodium hydroxide solution with the sulfuric acid standard titration solution.

2NaOH+H _?2SO ₄→Na ₂SO ₄+2H ₂O

Detection example is as follows:

Example 1:

Take by weighing 0.6g paraformaldehyde sample, be accurate to 0.0001g, in the 250mL conical flask, accurately add 50.0mL Standard Volumetric Solutions for Sodium Hydroxide (C (NaOH))=1mol/L, add lentamente again 3% superoxol of the new preparation of 50ml, shake gently every now and then conical flask to reacting completely, be cooled to room temperature, leave standstill 10min, then add 6 bromthymol blue indicator solutions (10g/L), with sulfuric acid standard titration solution (C(1/2H ₂SO ₄)=1mol/L) is titrated to solution and becomes blue-green.Do simultaneously blank test.Record numerical value five times and be respectively 96.07%, 96.10%, 96.09%, 96.10%, 96.10%, mean value is 96.09, and the coefficient of variation is 0.04%.

Example 2:

Take by weighing 0.6g paraformaldehyde sample, be accurate to 0.0001g, in the 250mL conical flask, accurately add 50.0mL Standard Volumetric Solutions for Sodium Hydroxide (C (NaOH))=1mol/L, add lentamente again 3% superoxol of the new preparation of 50ml, shake gently every now and then conical flask to reacting completely heating water bath 5 minutes, be cooled to room temperature, leave standstill 10min, then add 6 bromthymol blue indicator solutions (10g/L), with sulfuric acid standard titration solution (C(1/2H ₂SO ₄)=1mol/L) is titrated to solution and becomes blue-green.Do simultaneously blank test.Record numerical value 2 times and be respectively 96.04%, 96.06%, mean value is 96.05%.

Example 3:

Take by weighing 0.6g paraformaldehyde sample, be accurate to 0.0001g, in the 250mL conical flask, accurately add 50.0mL Standard Volumetric Solutions for Sodium Hydroxide (C (NaOH))=1mol/L, add lentamente again 3% superoxol of the new preparation of 50ml, shake gently every now and then conical flask to reacting completely, heating water bath 10 minutes is cooled to room temperature, leaves standstill 10min, then add 6 bromthymol blue indicator solutions (10g/L), with sulfuric acid standard titration solution (C(1/2H ₂SO ₄)=1mol/L) is titrated to solution and becomes blue-green.Do simultaneously blank test.Record numerical value 2 times and be respectively 96.05%, 96.07%, mean value is 96.06%.

Example 4:

Take by weighing 0.6g paraformaldehyde sample, be accurate to 0.0001g, in the 250mL conical flask, accurately add 50.0mL Standard Volumetric Solutions for Sodium Hydroxide (C (NaOH))=1mol/L, add lentamente again 3% superoxol of the new preparation of 50ml, shake gently every now and then conical flask to reacting completely, heating water bath 20 minutes is cooled to room temperature, leaves standstill 10min, then add 6 bromthymol blue indicator solutions (10g/L), with sulfuric acid standard titration solution (C(1/2H ₂SO ₄)=1mol/L) is titrated to solution and becomes blue-green.Do simultaneously blank test.Record numerical value 2 times and be respectively 96.05%, 96.07%, mean value is 96.06%.

Claims (2)

1. the rapid assay methods of a paraformaldehyde content, it is characterized in that: step is as follows:

Take by weighing the paraformaldehyde sample, place container, add sodium hydroxide solution, add superoxol to reacting completely again, cooling adds the bromthymol blue indicator solution, and be titrated to solution with the sulfuric acid standard titration solution and become blue-green,

Paraformaldehyde content X% is calculated as follows:

$X=\frac{(V_0-V)C\×3.003}{m}\×100$

In the formula:

The content of X-paraformaldehyde, in formaldehyde, %;

The concentration of C-sulfuric acid standard titration solution, mol/L;

The volume of the sulfuric acid standard titration solution that V-titration sample consumes, ml;

V ₀The volume of the sulfuric acid standard titration solution that-titration blank consumes, ml;

3.003-with 1.00ml sulfuric acid standard titration solution C(1/2H ₂SO ₄)=1mol/L, g;

The quality of m-sample, g.

2. the rapid assay methods of paraformaldehyde content according to claim 1, it is characterized in that: temperature of reaction is room temperature.