That level of precision handles the smallest samples, and it can be used in many applications, from mining and emissions testing to elemental analysis and drug discovery. Such a high-precision instrument, though, needs some special features.
When asked about some of the key applications of an ultramicrobalance, Walter Krebs, senior product manager for weighing and dosing at Mettler-Toledo (Greifensee, Switzerland), mentions “drug discovery, especially in the lead-optimization process, where the smallest amounts of possible new drugs have to be analyzed.” He adds, “Since often only very small amounts of samples are available for all the required analytical tests, the users try to save as much sample as possible.”
In emissions testing, Krebs says, “particulate matter is collected on filters, which are weighed on microbalances, and the weight of these particles is often very low, and many regulations require the use of a microbalance for this application.”
Some of the applications might even be unexpected. For example, Radoslaw Wilk, senior product manager at RADWAG Balances and Scales (Radom, Poland), points out that ultramicrobalances can be used to calibrate pipettes to volumes in the microliter range. He adds, “These balances can also be used for novel technologies in general.” As an example of that, Canadian scientists used an ultramicrobalance to measure particles in an infant’s nasal pathways, and reported in a 2015 issue of the Journal of Aerosol Medicine and Pulmonary Drug Delivery that “Electrostatic charge on particles can affect this deposition.”
Tracking the temperature
Such fine measurements depend intimately on the ambient conditions. To track that, RADWAG ultramicrobalances include an internal ambient conditions module, which measures humidity, pressure, and temperature. “If the ambient conditions are very bad, the balance won’t even be stable,” Wilk explains, “and the results will be continuously changing.”
A good ultramicrobalance provides internal adjustments. “The user can choose the setting for the adjustments,” Wilk says.
Likewise, Mettler-Toledo uses an active temperature control system that, Krebs says, “keeps the temperature in the weighing cell stable.” In combination with improved signal processing, says Krebs, this “leads to 25 percent better measurement performances.”
The real question is how this all works out in the lab. Adam Paganini, a marine researcher at San Francisco State University in California, says, “Probably the most key feature that matters to me in a microbalance is its resistance to drift throughout the day.” Dealing with that drift can take some effort from the scientist. He adds, “The microbalance needs to be continuously calibrated to function properly—maybe more than it’s supposed to be.”
Check the connections
According to Micro Scale Measurement, by RADWAG’s research laboratory manager Slawomir Janas, “Most balances with module design use cables connecting particular components. Such [a] solution is the most common one but not always satisfactory.” To get the best results from an ultramicrobalance, scientists often want a platform that provides connectivity. “Our solution offers features like wireless connectivity between a computer terminal and the weighing module,” Wilk says. “So you could, for example, put the weighing module in a vacuum chamber.”
In a similar move to help users, Mettler-Toledo developed a new touchscreen terminal that, Krebs says, comes with a “new user interface and a second ‘SmartView’ terminal.” He adds, “The new user interface enables training-free weighing and makes manual result capture obsolete.”
The take-home message for ultramicrobalances is: Look for every opportunity to enhance the accuracy, repeatability, and ability to document the conditions of the measurement. Features like these must be included in a platform to ensure ongoing and precise results.
For additional resources on balances, including useful articles and a list of manufacturers, visit www.labmanager.com/balances