METTLER TOLEDO ME PL-E Series Analytical Balance

Overview

The METTLER TOLEDO ME PL-E Series Analytical Balance is an entry-level precision weighing instrument engineered for routine laboratory applications requiring reliable 0.1 mg readability and consistent repeatability of ±0.08 mg. Built upon METTLER TOLEDO’s legacy of Swiss manufacturing excellence, the ME PL-E integrates a high-stability electromagnetic force compensation sensor with a rigid die-cast aluminum chassis and impact-resistant ABS polymer housing—delivering mechanical robustness without compromising sensitivity. Its measurement principle relies on real-time feedback-controlled electromagnetic restoration, where the restoring force required to maintain the load cell in equilibrium is directly proportional to sample mass. This architecture ensures minimal drift under ambient temperature fluctuations and supports stable operation in non-climate-controlled lab environments. The balance meets fundamental metrological requirements for Class I analytical use per OIML R 76 and ISO/IEC 17025–compliant weighing processes, serving as a foundational tool for quality control, formulation, sample preparation, and educational laboratories.

Key Features

• 0.1 mg readability with verified repeatability of 0.08 mg across the full 120 g capacity range
• Dual calibration capability: user-initiated external calibration using traceable weights (NIST-traceable砝码 recommended), plus optional internal calibration models (ME-IC variants)
• Ergonomic front-panel LCD display with large, high-contrast digits and tactile membrane keypad optimized for gloved operation
• RS232 serial interface standard—enables direct connection to thermal printers, PCs, or LIMS systems for automated data capture and audit trail generation
• Overload protection circuitry prevents sensor damage from accidental overloading up to 150% of maximum capacity
• Modular design facilitates service access and long-term calibration stability verification per ISO 17025 Clause 6.5

Sample Compatibility & Compliance

The ME PL-E accommodates standard laboratory containers—including weighing boats, vials, crucibles, and filter papers—via its Φ90 mm stainless steel weighing pan. Its open-front draft shield configuration allows rapid sample exchange while maintaining sufficient environmental isolation for sub-milligram measurements. The balance conforms to electromagnetic compatibility standards EN 61326-1 and safety standard EN 61010-1. While not pre-certified for FDA 21 CFR Part 11, its RS232 output supports integration with validated third-party data acquisition software that implements electronic signatures, audit trails, and user access controls required under GLP and GMP frameworks. Routine performance verification can be executed using calibrated test weights meeting ASTM E617 specifications.

Software & Data Management

Data export follows ASCII-based RS232 protocol with configurable transmission formats (e.g., SICS or custom delimiter strings), enabling seamless ingestion into Excel, LabWare LIMS, or proprietary QA databases. The balance supports automatic print-on-stabilization mode and time/date stamping when paired with compatible serial printers. Though it lacks built-in application software, its firmware structure permits firmware updates via METTLER TOLEDO’s ServiceLink utility, ensuring continued alignment with evolving regulatory expectations. For labs implementing ALCOA+ data integrity principles, the device serves as a compliant endpoint when paired with validated middleware that enforces data immutability and user authentication.

Applications

• Quantitative sample preparation in pharmaceutical QC labs (e.g., active ingredient dispensing prior to HPLC analysis)
• Gravimetric titration standardization and reagent stock solution preparation
• Material loss-on-drying (LOD) determinations per USP
• Education: undergraduate chemistry and materials science laboratories emphasizing measurement uncertainty fundamentals
• Environmental testing labs performing filter weight analysis for particulate matter (PM_2.5/PM₁₀) quantification
• Food testing facilities conducting moisture content and ash residue assays per AOAC methods

FAQ

Is internal calibration available on the ME PL-E model?
The base ME PL-E supports external calibration only; however, the ME-IC variant (same mechanical platform) includes a motorized internal calibration mechanism activated by temperature drift or user command.
What is the warm-up time required before first use?
A minimum 30-minute stabilization period at constant ambient temperature (18–23 °C, ≤50% RH) is recommended to achieve rated repeatability and linearity.
Can the balance be used in a fume hood?
Yes—provided airflow velocity at the pan level remains below 0.2 m/s and the unit is mounted on a vibration-isolated surface; draft shields must remain fully assembled.
Does the RS232 interface support USB conversion?
Yes, when used with industry-standard RS232-to-USB adapters compliant with FTDI chipset drivers; METTLER TOLEDO validates communication using its own MT-SICS software suite.
How often should performance verification be performed?
Per ISO/IEC 17025:2017, verification frequency must be risk-based: daily for critical QC steps, weekly for routine tasks, and after relocation or maintenance—using certified reference weights traceable to national standards.