How to Use an Analytical Balance

This document explains how to use an analytical balance in the laboratory and provides a calibration and use log suitable for a regulated setting. An analytical balance is one of the most commonly used pieces of equipment in biotechnology laboratories because it is designed for very precise measurements, accurate to four decimal places (0.0001 g). Before use, confirm you are wearing appropriate personal protective equipment (lab coat, gloves, goggles) and that the balance, weigh boats or weighing paper, and a lab notebook are ready.

Instrument Details

• A small paper clip weighs about 1 gram, giving a useful reference for the scale of items the balance is meant to handle.
• Do not weigh items heavier than the maximum capacity, as this will damage the balance.

Calibration Schedule

The source material does not specify a formal calibration frequency, due date, calibration procedure reference, or responsible role for periodic calibration; a regulated log should capture these details in full.

Before each weighing session, complete the following pre-use verification steps:

Standards Used

The source material does not reference certified reference standards, lot numbers, certificates, expiration dates, or traceability documentation; a regulated calibration log should list these items where applicable.

The observed procedures instead describe target sample weights used during routine weighing, for example a target of 1.5 grams of sodium bicarbonate and 12.19 grams of powdered Tris Base, with an acceptance range of 12.17–12.21 g (±0.02 g) for the Tris Base example.

Calibration Results

Follow these steps when weighing a sample, using weighing paper for quantities under five grams:

1. Fold opposite corners of the weighing paper together and crease; repeat for the other set of corners to create a stable surface.
2. Open the balance's side doors and place the folded weighing paper on the balance pan.
3. Close the side doors and press the TARE button to zero out the weight of the paper.

4. Use a lab scoop to slowly add sample to the weighing paper on the pan.
5. Close the glass doors after each addition to prevent air currents from affecting the reading, and wait for the balance to stabilize before reading the value.

The table below records the measured values observed during use:

For larger quantities, use a weigh boat instead of weighing paper: place the weigh boat on the pan, close the doors, press TARE to zero the boat, then slowly add material until the display reads the target value, closing the doors before taking the final reading.

Record every final weight in the lab notebook immediately after the reading is taken.

Maintenance

Perform the following maintenance actions at the end of a weighing session, especially at the end of the day:

Out-of-Tolerance Actions

The source material does not describe a formal out-of-tolerance procedure, impact assessment, affected data review, quarantine process, or corrective action; a regulated log should define each of these steps.

One related caution from the source: never weigh an item heavier than the balance's maximum capacity, as doing so will damage the balance and should trigger removal from service pending inspection.

Approval

The source material does not include a reviewer name, approval date, or release-to-use decision; a regulated log should record who reviewed the results and confirmed the balance's release to service.

What's Next

After practicing hands-on use of the analytical balance with appropriate personal protective equipment, clean the balance and organize the workspace by returning chemicals and equipment to their designated storage locations. If further training is needed, life science courses can be found through resources such as nccommunitycolleges.edu or ncbionetwork.org.