LimsPulse
Physical testing

Microbalance

A very sensitive balance that reads to 0.001 mg (1 µg) or better. It is used when the sample is only a few milligrams, for example a potent reference standard or a DSC sample.

  • Pharmaceutical
  • Biotech
  • Chemicals
  • Environmental testing
  • Academic research
  • Materials science
OVERVIEW

What is Microbalance?

A microbalance weighs very small masses. A typical microbalance has a capacity of a few grams (often 2–10 g) and a readability (d) of 0.001 mg, which is 1 µg or 0.000001 g. An ultra-microbalance reads to 0.1 µg. By comparison, a normal analytical balance reads to 0.1 mg, so a microbalance shows 100 times more detail.

It works on the same electromagnetic force restoration principle as an analytical balance, but everything is scaled down and isolated. The weighing chamber is small, the draught shield is close-fitting, and on many models the electronics sit in a separate box so their heat does not disturb the weighing cell.

At the microgram level the environment matters more than the balance. A breath, a warm hand, a static charge or a footstep can change the reading. Microbalances therefore sit on heavy anti-vibration tables in stable rooms, are used with anti-static devices, and have a minimum weight that must be determined where they stand.

Used for

  • Weighing a few milligrams of a potent or expensive reference standard
  • Preparing small-volume stock solutions where only a little material is available
  • Weighing samples into DSC and TGA pans
  • Weighing filters before and after collecting particulate or aerosol samples
  • Sample weighing for elemental (CHN) microanalysis
  • Gravimetric checks of low-volume pipettes and dispensers
AT A GLANCE

How it works

  1. 01

    Load

    A small container with the sample is placed on the pan inside the close-fitting draught shield.

  2. 02

    Displacement

    The pan and lever move by a tiny amount under the extra mass.

  3. 03

    Position sensing

    An optical sensor detects the movement away from the null position.

  4. 04

    Force restoration

    The control circuit raises the coil current until the magnetic force returns the pan to the null position.

  5. 05

    Filtering

    The signal is averaged and filtered to remove small disturbances, then converted to mass using the stored adjustment.

  6. 06

    Record

    Once stable, the reading is printed or sent to the LIMS with the balance ID, date and time.

Read the full working principle

Advantages

  • Readability of 1 µg or better allows very small sample sizes
  • Saves scarce or expensive reference material
  • Lower minimum weight than an analytical balance, often a few milligrams
  • Built-in internal adjustment weights on most models
  • Direct data transfer to LIMS with audit trail on modern models

Limitations

  • Extremely sensitive to draughts, vibration, temperature drift and static
  • Small capacity, usually only a few grams including the container
  • Needs a dedicated, stable room and a heavy weighing table
  • Long warm-up and stabilisation times
  • Weighing is slow; hygroscopic or volatile samples change during the weighing
  • Expensive to buy and to calibrate
CALIBRATION

3 calibration procedures

In LimsPulse · Calibration Management

Keep every Microbalance in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

See how