LimsPulse
Microbalance · Calibration procedure

Accuracy

Weighs a calibrated weight between 5% and 100% of capacity and compares the reading with its certified value. Also called the sensitivity test.

PURPOSE

Why this is checked

Confirms that the balance's sensitivity adjustment is correct, so that readings are true and not only repeatable.

Frequency

Typically every 6 or 12 months, and after repair, relocation or a failed daily check, as defined in your calibration SOP.

Learn how the Microbalance works
YOU WILL NEED

Standards & tools

  • Calibrated test weight between 5% and 100% of capacity, e.g. a 5 g OIML class E1 weight for a 6 g microbalance, with certificate stating its conventional mass
BEFORE YOU START

Prerequisites

  • Balance level, clean and warmed up
  • Internal adjustment run
  • Weight at room temperature and handled only with forceps
PROCEDURE

Step by step

  1. 1Zero the balance with the doors closed.
  2. 2Place the test weight centrally, close the doors and record the stable reading.
  3. 3Remove the weight and confirm the reading returns to zero.
  4. 4Repeat as your SOP requires (often three times) and calculate the mean.
  5. 5Compare the mean reading with the certified value.
RECORD

Example observation table

Certified value (g)Reading 1 (g)Reading 2 (g)Reading 3 (g)Mean (g)% error
5.0000025.0000055.0000045.0000065.000005+0.00006%
CALCULATION

How to calculate the result

% error = (Mean reading − Certified value) ÷ Certified value × 100
  1. Mean = (5.000005 + 5.000004 + 5.000006) ÷ 3 = 5.000005 g
  2. Difference = 5.000005 − 5.000002 = 0.000003 g (3 µg)
  3. % error = 0.000003 ÷ 5.000002 × 100 = 0.00006%
ACCEPTANCE CRITERIA

Pass if

  • Reading within 0.10% of the test weight value (USP <41>). Most SOPs also apply a tighter internal limit based on the manufacturer's specification.
IF IT FAILS

What to do

  • Run the internal adjustment and repeat.
  • If it still fails, label the balance 'Out of calibration' and call service.
  • Assess results since the last passing calibration.
MORE

Other Microbalance calibrations

In LimsPulse · Calibration Management

LimsPulse schedules this calibration, records the result against limits, and blocks the instrument everywhere if it fails or goes overdue.

See how