Mettler Toledo XP6U Ultra-Microbalance – Used & Refurbished
The Mettler Toledo XP6U Ultra-Microbalance is an exceptionally sensitive laboratory weighing instrument designed for measurements where even conventional microbalance resolution is insufficient. With a 6.1 g maximum capacity and 0.0001 mg / 0.1 µg readability, the XP6U can resolve mass changes down to one ten-millionth of a gram, making it suitable for demanding pharmaceutical, chemical, environmental, materials science, metrology, and advanced research applications.
Available used and refurbished from American Instrument Exchange, the Mettler Toledo XP6U combines ultra-micro weighing performance with proFACT automatic internal adjustment, a motorized draft shield, SmartSens infrared sensors for hands-free operation, a color touchscreen, MinWeigh functionality, configurable user accounts, extensive quality-management functions, and multiple connectivity options.
Because measurements at 0.1 µg resolution are extraordinarily sensitive to vibration, airflow, temperature changes, static electricity, and operator technique, proper installation is essential to achieving the performance capabilities of the XP6U.
Each XP6U is inspected, cleaned, calibrated, and tested for weighing performance before shipment and includes a 90-day warranty from American Instrument Exchange.
Key Features
-
6.1 g maximum weighing capacity
-
0.0001 mg / 0.1 µg readability
-
Ultra-microbalance weighing performance
-
Repeatability limit at maximum load of 0.0004 mg / 0.4 µg
-
Repeatability at low gross load of approximately 0.0002 mg / 0.2 µg
-
Linearity deviation of approximately 0.004 mg / 4 µg
-
Settling time of 15 seconds or less
-
proFACT automatic internal adjustment
-
Motor-driven draft shield
-
SmartSens infrared sensors for hands-free operation
-
Color touchscreen interface
-
MinWeigh minimum-weight monitoring
-
SmartTrac graphical weighing aid
-
Configurable user accounts with password protection
-
Multiple built-in applications
-
RS232C and auxiliary interfaces
-
Optional additional connectivity
-
Under-pan weighing capability
-
Used, refurbished, calibrated, and tested by American Instrument Exchange
-
90-day warranty included
Overview
The Mettler Toledo XP6U operates at a substantially higher level of sensitivity than conventional analytical, semi-micro, or microbalances.
A typical analytical balance provides 0.1 mg / 100 µg readability.
A semi-microbalance may provide 0.01 mg / 10 µg readability.
A conventional microbalance may provide 0.001 mg / 1 µg readability.
The XP6U goes another step further, providing 0.0001 mg / 0.1 µg readability.
This means the XP6U can display mass changes one thousand times smaller than a conventional 0.1 mg analytical balance.
That degree of resolution is valuable when working with extremely small quantities of expensive, scarce, potent, degradable, or hazardous material.
It also makes the XP6U useful for applications involving filters, particulate matter, residues, coatings, fibers, microcomponents, and other samples where extremely small changes in mass must be detected.
Common Applications
The Mettler Toledo XP6U is well suited for ultra-low sample weighing, pharmaceutical research, active pharmaceutical ingredient analysis, reference-material preparation, filter weighing, particulate analysis, residue determination, elemental and chemical research, materials characterization, microcomponent weighing, coating analysis, gravimetric analysis, and other ultra-high-resolution weighing applications.
Pharmaceutical and biotechnology laboratories can use the XP6U when working with extremely small quantities of potent compounds, reference materials, active ingredients, or other expensive substances.
Environmental laboratories can use ultra-micro weighing for filter-based particulate analysis and other procedures involving very small collected masses.
Materials science laboratories may use the XP6U to measure small fibers, films, coatings, microcomponents, or changes in material mass.
Research institutions and metrology laboratories can also use the XP6U when measurement requirements extend beyond the capabilities of conventional analytical and microbalances.
Ideal Laboratory Types
The XP6U is designed for pharmaceutical, biotechnology, chemical, environmental, materials science, metrology, nanotechnology, advanced research, analytical testing, and specialized quality-control laboratories.
Unlike a general-purpose analytical balance, an ultra-microbalance is usually purchased for a specific class of high-sensitivity applications.
The XP6U is most appropriate when a laboratory can clearly identify a need for sub-microgram resolution.
If 0.1 mg, 0.01 mg, or even 0.001 mg readability satisfies the measurement requirement, a less sensitive analytical, semi-micro, or microbalance may be easier to install and operate.
When 0.1 µg resolution is genuinely required, however, the XP6U provides a level of weighing performance that conventional laboratory balances cannot achieve.
Ultra-Microgram Weighing Performance
The defining specification of the XP6U is its 0.0001 mg / 0.1 µg readability across a maximum capacity of 6.1 g.
Mettler Toledo specifies a repeatability limit of approximately 0.0004 mg / 0.4 µg at maximum load.
At lower loads, repeatability can be substantially better. Manufacturer specifications identify repeatability of approximately 0.0002 mg / 0.2 µg at a 0.2 g gross load under defined conditions.
Linearity across the electrical weighing range is specified at approximately 0.004 mg / 4 µg.
Settling time is specified at 15 seconds or less.
These specifications illustrate an important characteristic of ultra-micro weighing: achieving the smallest possible displayed increment is only one part of measurement performance.
Repeatability, environmental stability, sample handling, calibration, and measurement uncertainty become equally important when working at fractions of a microgram.
Minimum Sample Weight & USP Applications
Minimum sample weight is particularly important when evaluating an ultra-microbalance.
The XP6U's 0.1 µg readability does not mean that 0.1 µg is an acceptable quantitative sample weight.
Minimum weight is determined primarily by repeatability and the maximum relative measurement uncertainty permitted by the laboratory's procedure.
Because repeatability can vary with load, installation environment, balance condition, and operating technique, the appropriate minimum weight should be established from the actual performance of the installed XP6U.
This is especially important for USP, GMP, GLP, or other regulated procedures.
The XP6U can enable laboratories to work with extraordinarily small sample quantities, but application-specific minimum weight should be verified through repeatability testing and the laboratory's applicable measurement-uncertainty requirements.
Controlling Vibration at 0.1 µg Readability
Proper vibration isolation is essential when operating the XP6U.
At 0.1 µg readability, vibration that would be completely irrelevant to a conventional laboratory balance can become visible in the weighing result.
For this reason, the XP6U should ideally be installed on a dedicated anti-vibration weighing table or comparable high-stability weighing surface.
A standard laboratory bench may not provide adequate isolation.
The balance should also be positioned away from centrifuges, shakers, vortex mixers, pumps, compressors, refrigerators, freezers, HVAC equipment, doors, elevators, and areas with substantial foot traffic.
Even structural vibration transmitted through the building can affect ultra-micro weighing.
Selecting the installation location should therefore be considered part of the XP6U weighing system—not simply a matter of finding available bench space.
Airflow, Temperature & Environmental Stability
Air movement and temperature stability become equally important at ultra-micro resolution.
The XP6U incorporates a motor-driven enclosed draft shield to protect the weighing chamber from surrounding air currents.
The balance should nevertheless be positioned away from HVAC vents, open doors, direct sunlight, rapidly changing room temperatures, and other sources of thermal instability.
Samples should be allowed to equilibrate to the weighing environment before critical measurements are performed.
A sample that is warmer or cooler than its surroundings can create convection currents inside the weighing chamber that influence the displayed result.
For ultra-micro weighing, controlling the environment surrounding the balance can be just as important as the technical specifications of the instrument itself.
Static Electricity & Ultra-Micro Samples
Electrostatic charge can become a major source of measurement error at 0.1 µg resolution.
Plastic containers, filters, powders, films, glassware, and low-humidity environments can all contribute to static buildup.
The electrostatic force acting on a sample can easily exceed the mass difference the XP6U is attempting to measure.
Laboratories performing ultra-micro weighing should therefore evaluate static as part of their weighing procedure.
Appropriate antistatic devices, conductive sample holders, controlled humidity, proper grounding, and good sample-handling technique may be required depending on the application.
proFACT Automatic Internal Adjustment
The XP6U incorporates Mettler Toledo's proFACT automatic internal adjustment system.
The balance can perform time- and temperature-controlled internal adjustment and linearization using its internal reference system.
This is particularly valuable for ultra-micro weighing because relatively small environmental changes can influence measurement performance.
Automatic internal adjustment helps maintain balance performance without requiring operators to repeatedly introduce external calibration weights into the weighing chamber.
proFACT does not eliminate the need for independent verification.
Laboratories operating under USP, GMP, GLP, ISO, or internal quality systems may still require routine performance testing with appropriate traceable external reference weights.
American Instrument Exchange verifies operation of the proFACT system and performs appropriate external performance testing during refurbishment.
Motorized Draft Shield & SmartSens Hands-Free Operation
The XP6U incorporates a motor-driven draft shield that reduces the need for operators to manually open and close the weighing chamber.
This is more than a convenience feature.
At ultra-micro resolution, physical interaction with the balance can introduce vibration, heat, and air movement.
Reducing unnecessary contact can therefore contribute to more stable weighing procedures.
Mettler Toledo also equipped the XP6U with SmartSens infrared sensors.
These sensors can be configured to perform selected operations without touching the balance, allowing functions such as opening or closing the draft shield to be performed hands-free.
For repetitive ultra-micro measurements, minimizing physical interaction can improve both workflow efficiency and measurement consistency.
MinWeigh & Quality Management
The XP6U incorporates MinWeigh functionality to help users monitor minimum-weight requirements.
Up to three minimum-weight values can be defined, allowing the balance to warn the operator when a sample falls below the established minimum.
This is particularly useful because readability alone does not indicate whether a sample quantity satisfies the uncertainty requirements of a quantitative procedure.
The XP platform also includes multiple quality-management functions designed to support laboratories operating under controlled weighing procedures.
These capabilities can help technicians recognize when a measurement falls outside predefined conditions rather than relying solely on operator judgment.
Touchscreen, User Accounts & SmartTrac
The XP6U uses a color touchscreen interface that provides access to weighing applications, balance settings, user profiles, and quality-management functions.
Up to eight configurable user accounts can be established with password protection.
This can help multi-user laboratories maintain individualized settings and more consistent operating procedures.
The balance also incorporates SmartTrac, a graphical weighing aid that allows users to visually monitor weighing progress, capacity, and defined tolerances.
Configurable information fields can be used for user or sample identification, and shortcut keys can provide rapid access to frequently used functions.
Connectivity & Laboratory Integration
The XP6U includes an RS232C interface and two auxiliary interfaces for compatible peripherals and accessories.
An additional interface slot can support optional connectivity depending on configuration, including options such as Ethernet, USB, additional RS232, Bluetooth, LocalCAN, and other compatible interfaces.
This allows the XP6U to be incorporated into electronic laboratory workflows rather than functioning solely as a standalone instrument.
Direct transfer of weighing results can reduce manual transcription and help laboratories maintain more consistent documentation.
Key Specifications
| Specification |
Mettler Toledo XP6U |
| Balance Type |
Ultra-Microbalance |
| Maximum Capacity |
6.1 g |
| Readability |
0.0001 mg / 0.1 µg |
| Repeatability Limit at Maximum Load |
0.0004 mg / 0.4 µg |
| Repeatability at Low Load |
Approx. 0.0002 mg / 0.2 µg at 0.2 g
|
| Linearity |
Approx. 0.004 mg / 4 µg
|
| Settling Time |
≤15 seconds |
| Adjustment |
Internal / automatic proFACT |
| Draft Shield |
Motorized enclosed draft shield |
| Hands-Free Operation |
SmartSens infrared sensors |
| Display |
Color touchscreen |
| User Accounts |
Up to 8 configurable accounts |
| Minimum Weight Monitoring |
MinWeigh |
| Weighing Aid |
SmartTrac |
| Primary Interface |
RS232C |
| Additional Interfaces |
2 auxiliary interfaces plus optional interface slot |
| Under-Pan Weighing |
Yes |
| Warm-Up Time |
Approx. 24 hours after initial connection |
| Operating Temperature |
5–40°C |
| Recommended Use |
Ultra-high-resolution quantitative weighing |
Choosing Between a Microbalance and Ultra-Microbalance
A conventional microbalance commonly provides 0.001 mg / 1 µg readability.
The XP6U provides 0.0001 mg / 0.1 µg readability, making it ten times more sensitive.
That additional resolution can be valuable when working with exceptionally small samples, expensive compounds, environmental particulates, microcomponents, films, coatings, or other applications involving mass changes below one microgram.
However, increased sensitivity comes with substantially greater environmental requirements.
An ultra-microbalance is more susceptible to vibration, air movement, temperature gradients, static electricity, and operator influence than a conventional microbalance.
Laboratories should therefore choose the XP6U when the application genuinely requires 0.1 µg resolution.
If 1 µg resolution is sufficient, a conventional microbalance may provide a more forgiving and cost-effective solution.
XP6U vs. XP6
The XP6U and XP6 both provide approximately 6.1 g maximum capacity, but their resolution differs significantly.
The XP6U provides 0.0001 mg / 0.1 µg readability.
The XP6 provides 0.001 mg / 1 µg readability.
The XP6U is therefore ten times more sensitive.
This makes the XP6U appropriate for ultra-micro applications where sub-microgram changes must be resolved.
The XP6 may be preferable when 1 µg readability satisfies the procedure because it provides the same general capacity with less extreme environmental sensitivity.
XP6U vs. XP2U
Both the XP6U and XP2U provide 0.0001 mg / 0.1 µg readability.
The primary difference is capacity.
The XP2U provides approximately 2.1 g maximum capacity, while the XP6U increases capacity to 6.1 g.
The XP6U therefore provides considerably greater working capacity while maintaining the same ultra-micro readability.
This can be particularly important when sample holders, filters, containers, or other tare components contribute significantly to the total load.
Why Installation Matters More for an Ultra-Microbalance
With many laboratory instruments, installation consists primarily of finding adequate bench space and electrical power.
An ultra-microbalance is different.
The weighing table, room location, airflow, vibration environment, temperature stability, static control, sample handling procedure, and operator technique all become part of the measurement system.
A properly functioning XP6U installed on an unstable laboratory bench may not achieve useful ultra-micro performance.
For this reason, laboratories purchasing an XP6U should evaluate the intended installation environment before putting the instrument into routine service.
A dedicated balance table, controlled room conditions, and appropriate antistatic measures can be just as important as the balance itself.
Refurbishment & Performance Testing
Every used Mettler Toledo XP6U sold by American Instrument Exchange is inspected, cleaned, refurbished as necessary, calibrated, and tested before shipment.
Ultra-microbalance testing requires considerably more care than testing a conventional laboratory balance.
Our technicians evaluate critical weighing characteristics including accuracy, repeatability, linearity, stability, calibration performance, and response across appropriate portions of the weighing range using suitable reference standards and controlled testing procedures.
The weighing system, proFACT automatic internal adjustment, motorized draft shield, SmartSens sensors, touchscreen, controls, leveling system, interfaces, and other installed functions are inspected and tested for proper operation.
The weighing chamber and accessible components are thoroughly cleaned, and the balance receives a final operational inspection before shipment.
Each refurbished XP6U includes a 90-day warranty from American Instrument Exchange.
Shipping & Installation Considerations
Ultra-microbalances require exceptionally careful handling during transportation.
American Instrument Exchange securely prepares the XP6U for shipment to protect its sensitive weighing system, motorized draft shield, touchscreen, and electronic components.
After installation, the XP6U should be allowed sufficient time to acclimate and reach thermal equilibrium before critical measurements are performed.
Mettler Toledo specifies a 24-hour warm-up period after initial connection to power. Once the balance remains connected and is subsequently activated from standby, it can be ready for operation much more quickly.
For demanding quantitative work, the balance should be installed on a dedicated anti-vibration weighing table in an environmentally stable location.
For regulated applications, installation should also be followed by appropriate calibration verification, repeatability testing, minimum-weight determination, or qualification according to the laboratory's quality system.
Related Laboratory Equipment
American Instrument Exchange maintains an extensive inventory of used and refurbished laboratory balances, including analytical balances, semi-micro balances, microbalances, and precision balances for applications ranging from routine sample preparation to high-resolution quantitative analysis.
Labs developing complete analytical or sample-preparation workflows can also source centrifuges, water baths, incubators, laboratory refrigerators, laboratory freezers, and other refurbished laboratory equipment from American Instrument Exchange.
Mettler Toledo XP6U Ultra-Microbalance FAQs
What is the maximum capacity of the Mettler Toledo XP6U?
The XP6U has a maximum weighing capacity of 6.1 g.
What is the readability of the XP6U?
The XP6U provides 0.0001 mg, or 0.1 µg, readability across its weighing range.
Is the XP6U a microbalance or ultra-microbalance?
The XP6U is best classified as an ultra-microbalance because it provides 0.1 µg readability, which is ten times finer than the 1 µg readability commonly associated with conventional microbalances.
What is the repeatability of the XP6U?
Mettler Toledo specifies a repeatability limit of approximately 0.0004 mg / 0.4 µg at maximum load. At lower loads, repeatability can be better; manufacturer specifications identify approximately 0.0002 mg / 0.2 µg at a 0.2 g gross load under defined conditions.
How quickly does the XP6U stabilize?
Mettler Toledo specifies a settling time of 15 seconds or less.
Does the XP6U have automatic internal adjustment?
Yes. The XP6U incorporates proFACT automatic internal adjustment and linearization.
Does the XP6U need an anti-vibration table?
For practical ultra-micro weighing, a dedicated anti-vibration weighing table or comparably stable installation is strongly recommended. At 0.1 µg resolution, building and equipment vibration can materially affect measurement stability.
How long should the XP6U warm up before use?
Mettler Toledo specifies approximately 24 hours of warm-up after the balance is initially connected to power. Keeping the balance powered allows it to maintain thermal stability, and operation from standby can then begin much more quickly.
What is the difference between the XP6U and XP6?
Both have approximately 6.1 g capacity, but the XP6U provides 0.1 µg readability while the XP6 provides 1 µg readability. The XP6U is therefore ten times more sensitive.
What is the difference between the XP6U and XP2U?
Both provide 0.1 µg readability. The primary difference is capacity: the XP6U provides 6.1 g capacity compared with approximately 2.1 g for the XP2U.
Can the XP6U weigh samples below 1 mg?
Yes. The XP6U is specifically designed for extremely small sample quantities. However, the acceptable minimum quantitative sample weight must be established from repeatability and the uncertainty requirements of the laboratory's procedure rather than readability alone.
Why purchase a refurbished Mettler Toledo XP6U?
A refurbished XP6U gives laboratories access to 0.1 µg ultra-micro resolution, 6.1 g capacity, proFACT automatic inter
