Titrimetric method for determination of total aldehyde content in styrene for industrial use (2)

6 sampling

Take samples according to GB/T3723 and GB/T6680

7 analysis steps

Use a pipette to draw 25 mL of styrene sample and add it to a conical flask with a stopper pre-set with 25 mL of methanol

Use 25mL methanol as a blank test

Note: Methanol is more toxic

8 Result calculation

The content w (mg/kg) of total aldehyde (calculated as benzaldehyde) is calculated according to formula (1):

Where:

V ₁ ——The value of the volume of the sodium hydroxide standard titration solution consumed by the test sample , in milliliter (mL);

V ₂ - Determination of methanol Numerical sodium oxide gas standard titration solution consumed in the blank volume in milliliters (mL);

c—— The value of the concentration of sodium hydroxide standard titration solution, the unit is mole per liter (mol/L);

p—— The value of the density of styrene , in grams per cubic centimeter (g/cm ³ );

M -the most significant value of the molar mass of benzaldehyde , the unit is grams per mole (g/mol) (M=106.

9 Expression of analysis results

Report the analysis results as the arithmetic average of the two repeated determination results, and round off according to the provisions of GB/T8170 to the nearest 1 mg/kg

10 Precision

10.

In the same laboratory, the same operator, using the same instrument and equipment, did two repeated tests on the same sample.

10.

In any two different laboratories, different operators, using different instruments and equipment, at different time or the same time, the two single measurement results of the same sample measured, for the total aldehyde content of 40mg/kg For the sample, the difference is not more than 16mg/kg, assuming that the difference is not more than 5% in the case of more than 16mg/kg

11 Report

The report should include the following:

a) All information about the sample, such as the name of the sample, batch number, sampling location, sampling date, sampling time, etc.

b) The number of this part;

c) Analysis results;

d) Details and descriptions of any abnormal phenomena observed in the measurement;

e) the name of the analyst and analysis date

Related links: Titration method for determination of total aldehyde content in styrene for industrial use (1)