GB/T 5528-2008Animal and vegetable fats and oils -- Determination of moisture and volatile matter content (English PDF)

7.1 Instruments

Commonly used laboratory instruments, as well as the following.

7.1.1 Analytical balance: with a division value of 0.0001 g.

7.1.2 Dish, made of porcelain or glass, with a flat bottom, 80 mm ~ 90 mm in diameter, about

30 mm in depth.

7.1.3 Thermometer, with a scale range of at least 80 °C ~ 110 °C, about 100 mm in length, with a reinforced mercury bulb and with an expansion chamber at its upper end.

7.1.4 Sand bath or electric hotplate.

7.1.5 Desiccator, containing an efficient desiccant.

7.2 Operating Procedures

7.2.1 Preparation of test sample

In a dish (7.1.2) that has been pre-dried and weighed together with the thermometer (7.1.3), weigh-take about 20 g of the test sample, accurate to 0.001 g.

7.2.2 Determination

Heat the dish containing the test sample (7.2.1) to 90 °C on a sand bath or electric hotplate (7.1.4), and control the heating rate at about 10 °C/min. While heating, use the thermometer to stir it.

Reduce the heating rate and observe the rise of bubbles at the bottom of the dish. Control the temperature to rise to 103 °C ± 2 °C, and make sure it does not exceed 105 °C. Continue stirring, until no bubbles are released from the bottom of the dish.

To ensure that the moisture is completely dissipated, repeat the steps of heating to 103 °C ± 2

°C and cool to 90 °C several times. Place the dish and thermometer in the desiccator (7.1.5), cool to room temperature, and weigh it, accurate to 0.001 g. Repeat the above operation, until two consecutive results do not exceed 2 mg.

7.2.3 Number of determinations

For the same test sample, conduct two determinations.

8.1 Instruments

Commonly used laboratory instruments, as well as the following.

8.1.1 Analytical balance: with a division value of 0.001 g.

8.1.2 Glass container: with a flat bottom, about 50 m in diameter, and about 30 mm in height.

8.1.3 Electric drying oven: with the main control temperature of 103 °C ± 2 °C.

8.1.4 Desiccator, containing an efficient desiccant.

8.2 Operating Procedures

8.2.1 Preparation of test sample

In a pre-dried and weighed glass container (8.1.2), in accordance with the expected moisture and volatile matter content of the test sample, weigh-take 5 g or 10 g of test sample, accurate to 0.001 g.

8.2.2 Determination

Place the glass container containing the test sample (8.2.1) in the electric drying oven (8.1.3) at

103 °C ± 2 °C for 1 hour, then, transfer it into the desiccator (8.1.4), cool to room temperature, and weigh it, accurate to 0.001 g. Repeat the steps of heating, cooling and weighing. Each re- baking time is 30 minutes, until the difference between two consecutive weighings respectively does not exceed 2 mg or 4 mg, depending on the mass of the test sample (8.2.1).

NOTE: the mass of the sample increases after repeated heating, indicating that the fat or oil has auto oxidized. At this time, take the minimum value to calculate the result, or use Method

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