Micro-Analytical Balances

A micro analytical balance is essentially a hybrid between a microbalance and an analytical balance. At first glance, it looks much like an analytical balance and indeed has the same overall structure. However, the weighing cell is carefully selected for its higher performance, offering six decimal place readability (1 µg), the same as most microbalances. Micro analytical balances have a second inner draft shield, which contributes towards the higher performance. This extra draft shield serves to create a more stable weighing environment by protecting the highly sensitive weighing cell from air movements. The weighing pan is also smaller. XPR micro analytical balances have a high capacity coupled with low minimum weight values, which makes them ideally suited to weighing small samples directly into large tare containers.

XPR micro analytical balances offer low minimum weight values. Even the 52 g capacity model has a USP minimum weight value of just 1.2 mg. This low minimum weight means you only need to use tiny amounts of your expensive, rare and potent substances, thereby reducing the costs of materials. Furthermore, the higher capacity enables you to weigh these very small samples directly into larger containers, avoiding the need to transfer samples via weighing paper, for example. ErgoClips support this process by holding your containers securely on the balance in precisely the right position for dosing. This simplifies the weighing process, avoids waste, and saves time.

XPR micro analytical balances are equipped with the SmartGrid hanging weighing pan. The grid structure significantly reduces the effects of air movements on the weighing cell, resulting in shorter stabilization times and faster delivery of results. This also makes XPR micro analytical balances ideal for working under challenging weighing conditions, such as in a fume cupboard. The two draft shields (inner and outer) on XPR micro analytical balances also help to maintain a stable environment within the weighing chamber, aided by Active Temperature Control technology (ATC).

XPR micro analytical balances also incorporate a range of features that help speed up weighing workflows: automatic doors can be operated with the wave of a hand, weighing tasks can be quickly accessed in the method library, and the StatusLight™ lets you see at-a-glance that the balance is ready for weighing without you needing to check it.

XPR micro analytical balances are fully compatible with our proprietary LabX™ laboratory software. LabX enables you to set up customized reports with all the information you need, even including an analysis of your weighing results. Conveniently, LabX can even print out a report for you automatically at the end of each process. LabX saves all data securely in a centralized database so you can access results and generate reports at any time. This is especially useful when preparing standards and sample solutions for research projects; you can define which set of data is most relevant to your experiment and create reports accordingly.

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When an item is placed on the weighing pan of an XPR micro analytical balance, an alternating current is applied to the grounded weighing pan. The patented StaticDetect technology examines the weight values recorded during the positive and negative half-cycles of the applied square wave signal. Any variation in the recorded weight values indicates the presence of electrostatic charges. Using this methodology, StaticDetect can determine the amount by which the electrostatic charges are affecting the weighing result and provides you with an onscreen warning when the detected error exceeds a predefined level.

For more information on electrostatics and the impact on weighing, download our white paper.

XPR micro analytical balances are cleverly designed to make cleaning easy. The two draft shields, hanging weighing pan, and the drip tray dismantle in seconds without the need for any tools and all parts can be washed in an industrial dishwasher.

In our free guide you can find a cleaning SOP as well as lots of tips and tricks, including cleaning methods and agents, to help keep your micro analytical balance in top condition. Download our free guide.

To determine the right micro analytical balance for your needs, there are some important questions to consider:

1. What is the smallest amount you want to weigh?
2. What is the largest amount you want to weigh?
3. How accurately do you want to weigh (i.e. what are your process tolerances)?
4. How high is your process risk (i.e. how serious are the consequences of an incorrect weighing result)?

Understanding uncertainty is also key to ensuring accurate results and avoiding errors. Every weight measurement on a micro-analytical balance, or indeed on any balance, is subject to a degree of uncertainty. At the lower end of the weighing range on a micro analytical balance, the dominant factor of the uncertainty is repeatability. It is important to understand that it is repeatability that defines the accuracy of a weighing instrument and not its readability. The readability is simply the smallest difference in weight that can be determined. The absolute smallest amount that can be weighed accurately on a balance is known as the balance minimum weight; below this value, the uncertainty is too large to trust the results. However, the smallest weight you can safely weigh for your own individual application also depends on your process tolerances and the process risk.

Our free GWP^® Recommendation service helps you choose the right balance for your application and accuracy requirements. Contact your local METTLER TOLEDO representative for more details.

On XPR micro analytical balances, the proFACT feature uses the balance's internal test weights to adjust the balance automatically whenever there is a change in ambient temperature. proFACT helps to ensure ongoing weighing accuracy.

Calibration assesses the performance of your micro analytical balance and should only be carried out by certified service technicians. As part of the calibration service, the technician may also adjust your balance if necessary and determine the balance minimum weight. At the end of the calibration service, you will be provided with a calibration certificate, which confirms that your balance is performing as expected and is required to prove traceability.

In the interval between calibrations, routine testing by the user is essential. Routine balance testing provides an early indication of any drift in balance performance and helps to avoid weighing results going out of tolerance.

METTLER TOLEDO's Good Weighing Practice™ (GWP^®) is a global scientific standard for the secure selection, calibration and operation of weighing equipment. Our GWP^® Verification service provides you with a comprehensive calibration and routine testing schedule based on your individual needs.

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Find out more about our calibration services and tailor a package to meet your precise needs.

With XPR micro analytical balances, all your results and process metadata are automatically saved to the results notepad. This removes the need to record results by hand and eliminates transcription errors. From the results notepad, the information can be easily transferred directly to a PC, or via a USB storage device.

For more comprehensive data management possibilities, LabX™ laboratory software takes care of all your data automatically and saves it in a secure centralized database. Furthermore, LabX provides SOP user guidance on the balance display and offers central management of tasks, instruments, and users. LabX also ensures data integrity and supports compliance with CFR 21 part 11.

Learn more about LabX.

Watch this short video to get an overview of LabX.