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Preserva Lab

Analytical Balances

Citizen’s Analytical Balances offers convenient features that provide accurate performance to accomplish and achieve the most sophisticated weighing tasks. On Citizen Analytical Balances, you can weigh just about anything from very lightweight samples to heavyweight objects. It is a class of balance designed to measure small mass in the sub-milligram range. The measuring pan of an analytical balance (0.1 mg or better) is enclosed inside a transparent chamber with doors to protect from dust particles and air currents that can affect the functioning and accuracy of the balance.

It measures the force needed to counter the mass being measured rather than using actual masses. As such, a calibration adjustment is required to compensate for gravitational differences. Additionally, an electromagnet is used to generate a force to counter the sample being measured and output the result by measuring the force needed to achieve balance.

Application:

A. Weighing a liquid, powder, or granular substance

1. Place the weighing container on the balance pan and close the doors.

2. Tare the container by briefly pressing the control bar. The readout will read zero with the container sitting on the pan. This allows the mass of your sample to be read directly.

3. Add the substance to be weighed. Be careful not to spill chemicals on the balance. If needed, you can remove the container from the weighing chamber while you add the sample provided that no one presses the control bar before you weigh your sample.

B. Weighing a solid object directly on the balance

If the object you need to weigh is a solid object, you can weigh it directly on the pan. Make sure the balance is set on zero. Open the chamber doors, and then carefully place the object on the balance pan. Close the doors, and read the mass of your object.

 

Accuracy Checking:

Accuracy verification of the analytical balance must be performed each time it is used for the creation of analytical calibrators or weighed-in controls from standard materials, as well as when gravimetrically checking the accuracy of pipettes. Checking a balance is very similar in concept to the checks we do in the laboratory for other analyses. There are four components to the testing of a laboratory balance: reproducibility, linearity, calibration, and corner load.

Precautions:

The environment of the lab, operating temperature, humidity, vibration, and ventilation currents can all affect performance. Therefore, it is instrumental in keeping the balance inside a clean and neat enclosed space. Make sure it is correctly levelled and that it is maintained and serviced regularly.

An analytical balance is so sensitive that it can detect the mass of a single grain of a chemical substance. Thus, if a method of direct weighing is used, the substance should be added to the tarred container to hold it, and never directly to the pan or even to weighing paper placed on the pan. Additionally, the container used should be completely dry and at room temperature, never at an elevated or reduced temperature. Even slight temperature differences can produce apparent changes in the mass of the container. Finally, the container should be completely dry, inside and out.

When you are done with the balance, make sure you have properly cleaned up any chemicals that may have spilt on the balance. At the end of the day, the balance can be turned off by lifting gently on the control bar.