Determination of trace water in butadiene for industrial use. Karl Fischer coulometric method (3)

9 Result calculation

9.

Express the moisture content (w ₁ ) in the sample by mass fraction (mg/kg ), and calculate it according to formula (1):

Where:

m ₁ —The absolute value of moisture displayed by the instrument, in micrograms (ug)

m—The mass of the sample, in grams (g)

9.

Express the moisture content (w ₂ ) in the sample by mass fraction (mg/kg ), and calculate it according to formula (2):

Where:

m ₁ —The absolute moisture content displayed by the instrument, in micrograms (ug);

V——The apparent volume of injection, the unit is liter (L);

P—The density of the sample at 0°C and 101325Pa, in grams per liter (g/L);

M——The relative molecular mass of the sample;

n—The conversion factor of the mass flow meter based on nitrogen for the sample (provided by the manufacturer of the flash meter)

9.

10 repeatability

In the same laboratory, the absolute difference between the two independent test results obtained by the same operator using the same equipment, using the same test method, and independently testing the same object in a short period of time should not exceed Table 3 The repeatability limit (r) is based on the premise that the repeatability limit (r) does not exceed 5%

Table 3 Repeatability

11 Report

The report should include the following content;

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

b) The number and measurement method of this standard;

c) Measurement results;

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

e) the name of the analyst and analysis date

Figure 1 Schematic diagram of Karl Fischer coulometric instrument assembly and cylinder capillary connection