Determination of trace moisture in fluoroalkanes for industrial use (2)

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Karl Fischer reagent should be calibrated every time

Add a certain amount of anhydrous methanol to the titration flask, immerse the electrode, turn on the power supply, turn on the electromagnetic stirrer, turn the measurement switch to the "calibration" position, adjust the potential to move the microammeter pointer to the full scale, and then measure The switch is fully "measured" position, and the pointer of the microammeter drops to zero

Use a 10uL micro syringe to draw 2uL～4uL of water, and weigh it to the nearest 0.

The titer T of Karl Fischer reagent to water is expressed in mg/mL and calculated according to formula (1):

Where:

m—The value of the mass of added water, in milligrams (mg);

V—the value of the volume of Karl Fischer reagent consumed during calibration, in milliliters (mL)

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Add a certain amount of anhydrous methanol to the titration flask and immerse the electrode

Under stirring, titrate to the end point with Karl Fischer reagent, and record the volume of Karl Fischer reagent consumed

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The mass fraction w ₁ of water in the sample , the value is expressed in %, calculated according to formula (2):

Where:

T—The titer of Karl Fischer reagent to water, in milligrams per milliliter (mg/mL);

V—the value of the volume of Karl Fischer reagent consumed during titration, in milliliters (mL);

m ₁ —The value of the mass of the sampled steel cylinder or glass syringe and the sample before sampling, in grams (g);

m ₂ —The value of the mass of the sample cylinder or glass syringe and the sample after the injection, in grams (g)
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