High-Precision Weighing – One Tube at a Time

Fully automated weighing with an accuracy of up to 0.1 mg.

Automated Weighing of Laboratory Tubes

Determining the weight of laboratory samples is often a critical yet time-consuming step in everyday laboratory work. In manual workflows, each tube must be placed on the balance individually, the stabilization of the measurement has to be awaited, the result documented, and the process repeated for the next tube. Automated weighing eliminates manual intervention and provides consistent, reproducible measurement results across different workflows.

Individual tube weighing can be performed as a standalone process, for example during quality control or incoming goods inspection, as well as integrated directly into automated workflows for inline process monitoring. This ensures reliable gravimetric data whenever precise weight information is required.

How Automated Weighing Works

Application

LABOTIQ Lab-Bot systems can be equipped with an optional integrated weighing cell mounted beneath the deck. The weighing unit features a universal load receptor designed to accommodate a wide range of laboratory tubes and vials, from small HPLC vials up to 50 ml centrifuge tubes.

For precise gravimetric measurements, the weighing cell is enclosed by a fully closed draft shield made of transparent material. This enclosure protects the measurement from air currents and environmental influences. Access to the weighing area is provided via a sliding cover on the top, allowing automated placement and removal of tubes.

Depending on the workflow, the Lab-Bot can transport tubes directly from the source rack to the weighing cell or route them via the multifunction unit. Within the multifunction unit, tubes can be identified by barcode and/or decapped prior to weighing. This enables gravimetric measurements of uncapped tubes when required. The removed cap is temporarily stored in a dedicated holder matched to the cap type and returned after weighing if needed.

Configurations

Depending on the application and accuracy requirements, automated weighing can be implemented in different configurations.

Process Control Weighing

Process control weighing represents the standard gravimetric application within automated laboratory workflows. It is based on a universal load receptor capable of accommodating a wide range of laboratory tubes and vials without format-specific adaptations.

This approach is well suited for inline process monitoring, filling control and general weight verification tasks. Due to the universal design of the load receptor, the achievable weighing accuracy is typically limited to a resolution of 1 mg, which is sufficient for most process control applications.

To further increase measurement reliability, analytical weighing steps can be repeated automatically. The number of individual weighings is defined by the user, and the resulting values are statistically evaluated to provide a robust and reproducible final result.

Analytical Weighing

For analytical weighing applications requiring higher accuracy, additional process-optimizing modifications are applied to minimize electrostatic and environmental influences. These measures are specifically tailored to a defined tube or vial type and require the use of a dedicated load receptor optimized for that format.

By implementing these adaptations, gravimetric measurements with an accuracy of up to 0.1 mg can be achieved. Due to the specialized nature of the weighing setup, analytical weighing configurations are typically optimized for one tube type at a time.

Use of Weighing Results

All weighing results are automatically written to the corresponding result file, where each value can be stored under a freely definable parameter name, such as “Weight”, “Tare” or “Gross”. This allows seamless integration of gravimetric data into existing data structures and workflows.

In addition, tolerance limits can be defined for each weighing result. Based on these limits, the Lab-Bot automatically evaluates whether a tube meets the specified criteria. Tubes that fall outside the defined thresholds can be identified and selectively sorted or excluded from further processing.

Weighing results can also be reused within subsequent process steps. For example, measured values may be printed directly on the tube label or incorporated into downstream workflows, enabling consistent documentation and traceability across the entire process chain.

Key Benefits

Fully Automated Gravimetric Measurement

Automated weighing of laboratory tubes eliminates manual handling and ensures consistent, reproducible measurement results.

Universal Tube and Vial Support

A universal load receptor accommodates a wide range of laboratory tubes and vials, from HPLC vials to 50 ml centrifuge tubes.

Process Control and Analytical Weighing

Supports both process control weighing with a resolution of 1 mg and analytical weighing with an accuracy of up to 0.1 mg, depending on the configuration.

Environmental Protection for Accurate Results

A fully enclosed draft shield protects the weighing process from air currents and external influences, ensuring stable and reliable measurements.

Statistically Secured Measurements

Analytical weighing steps can be repeated automatically, with user-defined repetitions and statistical evaluation of the measured values.

Data Integration and Process Decisions

Weighing results are stored digitally, evaluated against defined tolerance limits and can be used to control subsequent process steps or printed directly on labels.