Protocol for weighing on the microbalance

1. Use ethyl alcohol (acetone) on Kimwipe to clean the glass plate and tools.

2. Clean the microbalance with a brush

Pointed-end tweezers

round-end tweezers

flat-end tweezers

microspatula

3. Turn on the microbalance and wait for the microbalance to show “mg” at the bottom right corner.

4. Then, gently open the glass door of the microbalance. If preparing for EA or TCEA run, use the tweezers to grab an empty tin capsule by the edge and place on top of the balance. Otherwise, put weighing paper.

5. Push one of the “tare” buttons on either side of the microbalance to re-zero the weight

6. Take out the capsule/weigh paper and place gently on the glass plate in front of the microbalance.

7. Using the small scoop tool, carefully scoop out a small amount of sample/standard into the tin capsule/weigh paper. It is better to add in small increments rather than add too much and waste expensive standards or precious samples.

8. Using the tweezers to grab one edge of the tin capsule/weigh paper, carefully transfer the capsule/weighing paper and record the weight once the “mg” sign appears on one of the provided sample sheets.

9. Remove the capsule from the balance and place upright on glass plate in front of balance.

10. To fold the capsule closed, first use the tweezers to squeeze closed the top half of the capsule.

11. Then fold the capsule toward you, so that it is folded in half.

12. Next, fold the capsule in half, perpendicular to your first fold.

13. Use the flatter, broader headed tweezers to squeeze the doubly-folded capsule into a small cube. If you squeeze too hard, the capsule may pop up and away from you. To avoid this, use a flat spatula as a shield to hold the capsule in place. Likewise, squeezing too hard may cause the capsule to rip and your sample to leak out.

14. Place the cube into your sample tray, in the space you recorded your sample

mass (Spot D1 shown in the picture).

15. Clean the spatula between each sample/standard to avoid contamination.

16. When finished, clean microbalance by repeating steps 1 and 2. Turn off, and replace the microbalance cover.