Weigh All Your Options When Choosing a Balance
A balance is a common piece of laboratory equipment. Today’s electronic balances are capable of much more than simple mass determination. They can be used for many other applications, including density determination, pipette calibration, and animal or dynamic weighing.
It is critical to choose a balance that meets both performance and application requirements: specific application modes, connectivity, and GLP/GMP compliance assistance.
When choosing a balance, carefully consider the following:
Capacity: The largest weight that can be accurately weighed with the balance.
- What range of weights will be measured?
- Does the capacity of the balance allow for the heaviest samples to be measured (including the weight of tare containers like beakers)?
Readability: The smallest change in mass that corresponds to a change in the displayed value. Is the readability of the balance sufficient to accurately weigh your samples?
| Types | Readability |
|---|---|
| Precision Models | 1mg to 0.1 g |
| Analytical models | 0.1mg |
| Semi-micro models | 0.01mg |
| Micro models | 0.001mg |
Accuracy: The closeness of a measurement to the true value of that measurement.
A balance with a smaller readability will typically offer greater accuracy than a balance with a larger readability. For example, a balance capable of reading by 0.1mg will be more accurate than a 1mg balance.
Does your laboratory need to comply with a minimum weight standard, such as USP 41? If so, select a balance with the readability and repeatability that will ensure that even your smallest samples will not exceed the minimum weight tolerance of the balance.
Other Features
Modern electronic balances can have specialized weighing modes such as parts counting, dynamic weighing (for live animals), formulation and pipette calibration. These modes can help to save time and reduce operator error.
- Will the balance need to interface with existing equipment (computers, printers, LIMS)?
- Which communication interfaces are needed (ethernet, USB, RS-232)?
Compliance and Recordkeeping*
- What degree of data integrity and measurement traceability is required?
- Can the chosen balance produce attributable, contemporaneous and accurate physical or electronic records?
Total Cost
- Does the cost of the balance include all necessary options and accessories?
- Will one balance meet all of the laboratory’s requirements or will more than one balance be needed? (In some preferred over the purchase of a single balance.)
*For ISO, GLP or GMP requirements