Determine the Sample Mass

 

The equipment images in this topic may differ slightly from your equipment; however, the instructions are the same unless otherwise noted.

There are several different surface area ranges that require different protocol for optimal results.

  • If there is between 0.1 m2 and 1 m2 in the tube, follow the recommendations for balancing the free space using glass beads, along with filler rods, and measure the resulting free space difference.

  • If there is between 1 m2 and 5 m2 of total surface under test, measure the free space difference between the two tubes as a part of each analysis.
  • If there is between 5 m2 and 30 m2, use the option to calculate the free space difference between the two tubes using the density of the sample in the tube, along with the mass entered. There are some special considerations when using the tubes with the cylindrical bulb on the end as opposed to the straight-walled tubes.
  • If there is more than 30 m2 in the tube total, it may not be necessary to determine the free space difference between the two tubes as a part of the analysis.

Smaller quantities are required for samples having high surface areas. These samples require careful weighing after degassing because a small error may represent a considerable percent of total mass. Proper weighing techniques are most important in this case. Use no less than 100 mg to reduce the effect of weighing errors.

Care should be taken when loading powders: the accessory funnel is useful for this purpose. Large granules or chunks may be loaded with forceps.

Analysis results are expressed in units of surface area per gram of sample; therefore, it is important to know the true sample mass.

Follow the instructions on the Sample Data Worksheet and complete all fields to find the true sample mass.

  1. Record the sample tube identification on the Sample Data Worksheet.
  2. Place the sample weighing support on the balance. Tare the balance and allow it to stabilize at zero (0).
  3. Place the empty sample tube set (empty sample tube and stopper) on the sample weighing support and place it on the balance.
  4. Record the stabilized mass on the Sample Data Worksheet. Remove the sample tube set from the balance.
  Do not touch the sample with bare hands while performing the following steps. Doing so could affect the accuracy of results.
  1. Place a sample container on the balance. Tare the balance and allow it to stabilize to zero.
  2. Slowly pour the specified amount of sample into the sample container.
  3. Remove the rubber stopper, Seal Frit, Check Seal, or TranSeal from the sample tube.
  4. Use the sample tube funnel (provided in the accessories kit) and pour the sample from the weighing container into the sample tube.
  1. Replace either the rubber stopper, Seal Frit, Check Seal, or TranSeal.
  2. On the Sample Data Worksheet, record the following:
    • Mass of the sample tube set with the sample.
    • Subtract the Mass of empty sample tube set from the Mass of sample tube set plus sample.