Metrohm 876 Dosimat Plus Liquid Handler and Semi-Automatic Titrator

Overview

The Metrohm 876 Dosimat Plus is a precision-engineered liquid handling module designed for semi-automatic titration workflows in regulated analytical laboratories. Operating on the principle of gravimetric and volumetric reagent delivery under programmable control, it bridges manual titration rigor with digital reproducibility. Unlike fully automated titrators, the 876 integrates seamlessly into hybrid workflows where operator judgment—such as visual endpoint detection in colorimetric titrations—is retained while eliminating volumetric measurement error. Its architecture supports both real-time monitoring of titration curves via an integrated high-resolution display and post-run data export for audit-ready documentation. The system complies with core principles of GLP and GMP environments through traceable parameter logging, user-access-controlled method editing, and hardware-level compatibility with certified laboratory balances and printers.

Key Features

• High-contrast graphical display for live titration curve visualization, method parameter review, and on-screen editing without external PC dependency
• Dual-mode dispensing architecture: DOS mode enables manual lever-actuated dosing synchronized with real-time volume tracking and automatic result calculation; XDOS mode supports three deterministic dispensing profiles—fixed-volume, time-controlled, and flow-rate-controlled—each programmable with independent setpoints for volume (mL), duration (s), and delivery rate (mL/min)
• Native USB 2.0 host interface supporting plug-and-play connectivity to peripheral devices including keyboards, optical mice, USB thermal printers, commercial inkjet/laser printers, and mass storage drives—enabling direct report generation and method backup
• Optional RS-232/USB Box adapter for bidirectional communication with METTLER TOLEDO, Sartorius, or other ISO/IEC 17025-accredited analytical balances, enabling dynamic weight-based endpoint triggering and density-corrected concentration calculations
• Modular interoperability: Designed to operate in tandem with the Metrohm 805 Dosimat unit via synchronized serial handshake, permitting uninterrupted reagent supply across extended titration sequences without manual refilling or system interruption

Sample Compatibility & Compliance

The 876 Dosimat Plus accommodates standard 10–100 mL glass or PTFE-coated burettes and supports aqueous, alcoholic, and low-viscosity organic solvent systems (e.g., glacial acetic acid, methanol, chloroform) within operational temperature ranges of 15–30 °C. All fluidic pathways are chemically inert (EPDM, FKM, and borosilicate glass), ensuring compatibility with strong acids (HCl, HNO₃), bases (NaOH, KOH), redox reagents (KMnO₄, Ce(SO₄)₂), and complexometric titrants (EDTA). The instrument meets electromagnetic compatibility requirements per EN 61326-1:2013 and safety standards IEC 61010-1:2010. While not a standalone data integrity system, its USB logging and method versioning support alignment with FDA 21 CFR Part 11 when deployed within validated IT infrastructures that enforce electronic signature controls and audit trail retention.

Software & Data Management

No proprietary software installation is required for basic operation—the 876 functions autonomously using embedded firmware. However, it natively exports CSV-formatted titration logs (including timestamp, delivered volume, calculated result, operator ID, and method name) to connected USB storage. When integrated into Metrohm’s tiamo™ software environment (v3.2+), the device appears as a recognized peripheral, enabling centralized method deployment, remote calibration validation, and cross-instrument result aggregation. All parameter changes—including dosing thresholds, calculation coefficients (e.g., molar mass, dilution factor), and print formatting—are recorded with user ID and timestamp in non-volatile memory, satisfying minimum ALCOA+ data integrity criteria for raw data preservation.

Applications

• Pharmaceutical QC: USP acid-base titrations for assay of active pharmaceutical ingredients (APIs) such as aspirin, paracetamol, and sulfonamides
• Food & Beverage: AOAC 947.05 titrimetric determination of total acidity in wines, juices, and dairy products
• Water & Wastewater: Standard Methods 2320B alkalinity and hardness titrations using standardized EDTA and HCl solutions
• Chemical Manufacturing: In-process control of catalyst neutralization endpoints during polymer synthesis or esterification reactions
• Educational Labs: Pedagogical reinforcement of stoichiometric principles via reproducible manual-dose experiments with digital verification

FAQ

Can the 876 Dosimat Plus be used without a computer?
Yes—the unit operates independently with onboard display, method storage, and calculation engine. A PC is only required for advanced reporting or integration with tiamo™.
Does it support automatic equivalence point detection?
No—it does not include potentiometric or photometric sensors. Endpoint detection remains operator-dependent in DOS mode; XDOS is purely volumetric/time-based.
Is calibration traceable to national standards?
Burette calibration must be performed externally per ISO 8655-3 using certified weights and reference fluids; the 876 records calibration dates and operators but does not perform calibration itself.
What maintenance intervals are recommended?
Daily: Visual inspection of tubing and burette seal integrity. Quarterly: Replacement of peristaltic pump tubing and O-rings. Annually: Full functional verification against Metrohm Service Bulletin SB-876-04.
Can multiple 876 units be controlled from one PC?
Yes—via USB Hub or RS-232 multiplexer, provided each unit has a unique COM port assignment and tiamo™ is licensed for multi-instrument configuration.