CN104155293A - Improved detection method for sulfur dioxide - Google Patents

Abstract

The invention provides an improved detection method for sulfur dioxide. The detection method comprises the following steps: treating a sample; placing the sample into a special digestion bottle for Kjeldahl determination, putting the digestion bottle on an azotometer, inserting the lower end of an absorption tube into a lead acetate absorption liquid in an iodine number flask, adding a hydrochloric acid solution, then immediately capping a plug, carrying out heating and distillation and carrying out blank control test during detection; adding concentrated hydrochloric acid and an iodine standard solution into a distilled fluid, placing the obtained mixture in a dark place for a reaction for 2 min, rapidly titrating an excess iodine liquid in the distilled fluid by using a sodium hyposulfite standard solution, adding a starch indicator when the distilled fluid has a light yellow color after titration and terminating titration when a blue color turns into colourless; and calculating the content of sulfur dioxide in the sample according to the consumed amount of sodium hyposulfite. According to the invention, a Kjeldahl determination apparatus is used to replace a manually-built simple distillation apparatus, so the method is simple and easily practicable, reduces system errors and improves accuracy of analysis results.

Description

A kind of improved sulphuric dioxide detection method

Technical field

The present invention relates to a kind of improved sulphuric dioxide detection method.

Background technology

Sulphite and its esters are as the conventional bleaching agent of China, in many food processing process, normal smoked sulphur and the sulfite solution infusion process of adopting bleached, the composition sulphuric dioxide that bleaching agent plays a major role can cause eater to have sore throat, the bad reaction such as have a stomach upset has certain infringement to liver simultaneously.

Detect the conventional way of distillation of sulphuric dioxide, traditional way of distillation is utilized heating by electric cooker round-bottomed flask, and connects condenser pipe cooling, and building this covering device wastes time and energy, and temperature is wayward, allows experiment become loaded down with trivial details, has strengthened systematic error.

Summary of the invention

In view of this, the present invention proposes a kind of improved sulphuric dioxide detection method, the method is both simple, has reduced again systematic error, has improved precision of analysis.

For solving the problems of the technologies described above, technology of the present invention by the following technical solutions:

A kind of improved sulphuric dioxide detection method, comprises the following steps:

(1) sample preparation

Solid sample: cut or scissors is cut into broken lastly with cutter, mix, take the even sample of 5.00g stand-by;

Fluid sample: directly draw 5.0mL～10.0mL as sample, be placed in 500mL round bottom distilling flask stand-by;

(2) distillation

Sample is inserted to kjeldahl determination is special to be cleared up in bottle, add 100mL water, be placed on azotometer, insert in the lead acetate absorption liquid of the 25mL 20g/L in iodine flask absorption tube lower end, then clearing up the hydrochloric acid solution that adds 10mL 1+1 in bottle, capping plug immediately, adds thermal distillation, in the time being distilled to 200mL, make condenser pipe lower end leave liquid level, redistillation 1 minute by the device part of a small amount of distilled water flushing insertion lead acetate solution, is done blank test in detection simultaneously;

(3) titration

In distillate, add 10mL concentrated hydrochloric acid, the iodine mark liquid of 20mL 0.01mol/L, put dark place reaction 2 minutes, rapidly with excessive iodine liquid in the sodium thiosulfate standard solution titration distillate of 0.01mol/L, be titrated to after light yellow and add 1～2mL starch indicator, be titrated to by blueness and become colorless, 30 seconds echo bluenesss not, are terminal;

(4) result of calculation

Sulfur dioxide concentration calculates:

X=（A-B）×0.01×0.032×1000/m

Sulphuric dioxide total content in X-sample, unit is g/kg;

The volume of A-titration sample iodine standard titration solution used (0.01mol/L), unit is mL;

The volume of B-titration reagent blank iodine standard solution used (0.01mol/L), unit is mL;

0.032-1mL iodine standard solution (c(1/2I ₂)=1.0mol/L) quality of suitable sulphuric dioxide, g.

The hydrochloric acid solution of 1+1, the solution that water of hydrochloric acid+1 volume of 1 volume is mixed to get.

The beneficial effect that the present invention compared with prior art has is: the present invention adopts kjeldahl determination device to replace the simple and crude distilling apparatus that traditional craft is built, both simple, has reduced again systematic error, has improved precision of analysis; The indispensable device of this device when doing protein and distill in laboratory, too wastes if be only used for doing protein, and being used for analyzing sulphuric dioxide both can saving resource, had simplified again experimentation.

Embodiment

For allowing the more clear and intuitive understanding the present invention of those skilled in the art, below the present invention is further illustrated.

A kind of improved sulphuric dioxide detection method, comprises the following steps:

(1) sample preparation

Solid sample: respectively preserved fruit, auricularia auriculajudae, dictyophora phalloidea, white sugar, all product of mushroom five are cut with cutter or scissors is cut into broken lastly, mixed, take the even sample of 5.00g stand-by;

(2) distillation

Sample is inserted to kjeldahl determination is special to be cleared up in bottle, add 100mL water, be placed on azotometer, insert in the lead acetate absorption liquid of the 25mL 20g/L in iodine flask absorption tube lower end, then clearing up the hydrochloric acid solution that adds 10mL 1+1 in bottle, capping plug immediately, add thermal distillation, in the time being distilled to 200mL, make condenser pipe lower end leave liquid level, redistillation 1 minute, by the device part of a small amount of distilled water flushing insertion lead acetate solution, does not add the constant blank that does of other test procedures of sample simultaneously in detection and tests;

(3) titration

The iodine mark liquid of 10mL concentrated hydrochloric acid (massfraction is 36%-37%) and 20mL 0.01mol/L will be added respectively in the distillate obtaining in sample preparation test and blank test, put dark place reaction 2 minutes, rapidly with excessive iodine liquid in the sodium thiosulfate standard solution titration distillate of 0.01mol/L, be titrated to after light yellow and add 1～2mL starch indicator, be titrated to by blueness and become colorless, 30 seconds echo bluenesss are not terminal;

(4) result of calculation

Sulfur dioxide concentration calculates:

Sulfur dioxide concentration calculates:

X=（A-B）×0.01×0.032×1000/m

Sulphuric dioxide total content in X-sample, unit is g/kg;

The volume of A-titration sample iodine standard titration solution used (0.01mol/L), unit is mL;

The volume of B-titration reagent blank iodine standard solution used (0.01mol/L), unit is mL;

0.032-1mL iodine standard solution (c(1/2I ₂)=1.0mol/L) quality of suitable sulphuric dioxide, g.

By the content results of the sulphuric dioxide calculating in the present embodiment and classic method comparison, obtain table 1:

Table 1

Sample	Classic method	Improve one's methods	Error (%)
				1 preserved fruit	5.21	5.28	0.67
2 auricularia auriculajudaes	3.11	3.15	0.64
				3 dictyophora phalloidea	4.68	4.72	0.43
4 white sugar	6.58	6.74	1.20
				5 mushrooms	7.45	7.38	0.47

According to the interpretation of result of table 1, classic method and the measurement result difference of improving one's methods are not remarkable, and accuracy and the reappearance of measurement result are better, and Comparison of experiment results is stable.

The foregoing is only preferred embodiment of the present invention, in order to limit the present invention, within the spirit and principles in the present invention not all, any amendment of doing, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (1)

1. an improved sulphuric dioxide detection method, is characterized in that comprising the following steps:

(1) sample preparation

Solid sample: cut or scissors is cut into broken lastly with cutter, mix, take the even sample of 5.00g stand-by;

Fluid sample: directly draw 5.0mL～10.0mL as sample, be placed in 500mL round bottom distilling flask stand-by;

(2) distillation

Sample is inserted to kjeldahl determination is special to be cleared up in bottle, add 100mL water, be placed on azotometer, insert in the lead acetate absorption liquid of the 25mL 20g/L in iodine flask absorption tube lower end, then clearing up the hydrochloric acid solution that adds 10mL 1+1 in bottle, capping plug immediately, adds thermal distillation, in the time being distilled to 200mL, make condenser pipe lower end leave liquid level, redistillation 1 minute, by the device part of a small amount of distilled water flushing insertion lead acetate solution, does not add sample simultaneously and does blank test;

(3) titration

In distillate, add concentrated hydrochloric acid that 10mL massfraction is 36%-37% and the iodine mark liquid of 20mL 0.01mol/L, put dark place reaction 2 minutes, rapidly with excessive iodine liquid in the sodium thiosulfate standard solution titration distillate of 0.01mol/L, be titrated to after light yellow and add 1～2mL starch indicator, be titrated to by blueness and become colorless, 30 seconds echo bluenesss are not terminal;

(4) result of calculation

Sulfur dioxide concentration calculates:

X=（A-B）×0.01×0.032×1000/m

Sulphuric dioxide total content in X-sample, unit is g/kg;

The volume of A-titration sample iodine standard titration solution used (0.01mol/L), unit is mL;

The volume of B-titration reagent blank iodine standard solution used (0.01mol/L), unit is mL;

0.032-1mL iodine standard solution (c(1/2I ₂)=1.0mol/L) quality of suitable sulphuric dioxide, g.