G.G. Hatch Stable Isotope Laboratory

25 Templeton Street
Advanced Research Complex
Faculty of Science
University of Ottawa
Ottawa, ON Canada
K1N 6N5
Attn: P. Middlestead

Find us at:
25 Templeton Street
Advanced Research Complex (ARC)
Room 426

For all inquiries click here.

Paul Middlestead, Lab Manager
Tel: (613) 562-5800
ext. 6839 (office)
ext. 6836 (lab)

Dr. Ian Clark, Director

How to weigh samples on the microbalance

Note: No flat samples, they get stuck in the carrousel.
Check required amount of sample with Lab personnel before starting to weigh!


Sartorius MicrobalanceWe use a simple balance without the fancy electric doors, etc.  It has proven to be very reliable.  We get it checked once a year for accuracy.

Not to be confused with an analytical balance (digits to 0.0001g or 0.00001g), the microbalance has digits 0.001mg (0.000001g).

For elemental analysis (%NCHS) the higher the elemental percent, the more this kind of accuracy is critical.  





Make Model Readability (mg) Capacity(g) Pan size mm (inches)
Sartorius M2P 0,001/0,002/0,005 0,5/1/2 Ø 22 (0,86)


Tin capsules

Sizes of tin capsules


Isomass Scientific Catalogue No.
5 x 3.5
Typical EA-IRMS size. Use for up to 3mg sample.
8 x 5
Typical Elemental Analysis size. Use for up to 40mg sample.
12 x 5
EA-IRMS or EA. Often used for glass fibre filters. Use for up to 80mg sample.
10 x 10
EA-IRMS or EA. Often used for filters or sediments. Use for up to 200mg sample.

Note: Density of the sample material may affect the quantity of material able to fit in a particular size of capsule. Go up a size when necessary, but try not to exceed the weight limit for a size.


Tools required

       1     2    3    4    5

  1. Aluminium block for sample prep; good hard suface that is easy to keep clean
  2. Small angled spatula; micro spatulas are also handy for very small samples
  3. Blunt-ended forceps for squishing capsules without tearing or poking holes
  4. Fine-tipped angled forceps good for picking up capsules by top edge
  5. Flat forceps ("offset-tipped") with slight angle good for squishing air out of larger capsules before compressing
  6. Plastic tray with numbered wells to hold compressed capsules; with lid

Additional items: Kimwipes; (elastics or) tape to keep tray closed for storage and shipping. Beware: if elastics are too tight, the lid can bulge allowing samples out of their wells.



Place capsule on microbalance and tare

Using the fine angled forceps, place a tin capsule on the balance and Tare.

Remove the capsule from the balance and place on the aluminium block or some other smooth, clean surface.

Spatula with powder above capsule

Scoop the appropriate amount of sample material into the capsule; in most cases, this means having about 100µg of nitrogen, carbon or sulphur.

Place capsule back into balance; remove and adjust amount of material if necessary.

Record the weight (all digits).

Échantillon- Fermeture du haut de la capsules.jpg (7265 octets)Échantillon- Fermeture de la capsule.jpg (9374 octets)Échantillon- Plis de la capsules.jpg (7393 octets)







  • Use blunt-ended forceps to close the top of the capsule.
  • While holding the top closed, use flat-tipped forceps to squeeze out remaining air in the main portion of the capsule.
  • While holding the main portion of the capsule, fold top of capsule down.
  • Continue with blunt-ended forceps to fold capsule again if necessary, and form into a cube or a ball.

CAUTION: fine-tipped forceps and corners of flat-tipped forceps can puncture the capsule. Also, find a happy medium between getting all the air out and squeezing so hard the capsule breaks.

NOTE: if the capsule does crack, it is acceptable to slip it into a second capsule and close, except in the case of Elemental Analysis or significant loss of material.

Échantillon- Boule ou cube avec règle.jpg (5777 octets)








These are some examples of the original vs. the final sizes of the different tin capsules.
How you squish the capsules is up to you; however, the final result must be a cube or ball
that does not leak.

  • Store samples in a clean tray using the numbering system
    A1, A2, A3, ... B1, B2, ...
  • Fill out the submission form and e-mail it to the lab.
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Last updated: 2013.05.02