ChemTron MD 110 COD and MD 200 COD Photometric COD Analyzers

Overview

The ChemTron MD 110 and MD 200 COD Photometric Analyzers are benchtop and portable spectrophotometric instruments engineered for rapid, reliable quantification of chemical oxygen demand (COD) in wastewater, influent, effluent, and industrial process streams. These analyzers operate on the principle of photometric absorption measurement following closed-reflux digestion—per ASTM D1252 (Method B) and ISO 15705:2002—where dichromate oxidation under acidic, high-temperature conditions converts organic matter to CO₂, and the resulting colorimetric change (Cr³⁺ formation) is measured at two standardized wavelengths: 430 nm (for low-range samples) and 610 nm (for mid-to-high-range samples). Unlike electrochemical or titrimetric alternatives, this dual-wavelength photometric architecture eliminates interferences from turbidity and residual chloride, enabling direct analysis without dilution or correction factors across a 3–15,000 mg/L O₂ dynamic range when paired with ChemTron’s certified COD VARIO pre-filled reagent tubes.

Key Features

• Dual-wavelength optical system (430 nm and 610 nm) calibrated per ISO 15705:2002, ensuring traceable compliance with international standard methods
• IP65-rated rugged housing with sealed keypad and splash-resistant front panel—designed for laboratory, field, and plant-floor deployment
• Large, high-contrast backlit LCD display with intuitive icon-driven menu navigation; no external PC required for routine operation
• Integrated calibration verification protocol using included COD standard solutions (e.g., 50 mg/L and 500 mg/L O₂ reference standards)
• MD 200 variant includes internal rechargeable Li-ion battery (up to 8 h continuous use), USB-C data export, and auto-zero function with dark-current compensation
• Pre-programmed method library supporting all four COD VARIO reagent ranges, with automatic range selection and unit conversion (mg/L O₂, ppm, or mmol/L)

Sample Compatibility & Compliance

These analyzers accept standard 16-mm diameter COD VARIO pre-filled digestion tubes—certified to meet DIN EN ISO/IEC 17025 requirements for certified reference materials. The system accommodates undiluted samples within the specified range of each tube format: 3–150 mg/L O₂ (low-range), 15–300 mg/L O₂ (medium-range), 20–1500 mg/L O₂ (high-range), and 200–15,000 mg/L O₂ (ultra-high-range). Sample matrix compatibility includes municipal wastewater, food processing effluents, pharmaceutical rinse waters, and pulp & paper mill discharges. Chloride tolerance is up to 2000 mg/L (with optional Ag₂SO₄ interference suppression in digestion step). All instrument performance verifications—including photometric linearity, wavelength accuracy, and repeatability—are documented per ISO/IEC 17025 and support GLP/GMP audit readiness.

Software & Data Management

The MD 110 operates via embedded firmware with onboard storage for up to 500 test results, including timestamp, operator ID, sample ID, and selected method. The MD 200 adds USB-C connectivity for direct CSV export to LIMS or Excel, plus optional ChemTron LabLink software (Windows-based) for instrument configuration, method validation reports, and electronic signature-enabled result review. Both models support 21 CFR Part 11-compliant audit trails when used with validated software configurations—enabling secure user access control, change logging, and electronic record retention for regulated environments.

Applications

• Routine compliance monitoring of wastewater treatment plant influent/effluent per EU Urban Wastewater Treatment Directive and US EPA NPDES permit requirements
• Process control in bioreactor systems, where real-time COD trends inform aeration rate and sludge retention time adjustments
• Quality assurance of industrial pretreatment units handling chemical, textile, or brewery effluents
• Educational laboratories requiring robust, entry-level COD instrumentation aligned with ISO and ASTM curriculum standards
• Field-deployable verification of on-site digester performance or decentralized treatment system efficiency

FAQ

What digestion equipment is required to use the MD 110/MD 200?
A compatible COD digestion block—such as the ChemTron RD125 or equivalent 150 °C, 2-h reflux-capable heater—is required. Digestion must follow ISO 15705:2002 timing and temperature specifications.
Can the analyzer store calibration curves for multiple reagent lots?
Yes—each instrument retains up to five user-defined calibration sets, assignable to specific lot numbers of COD VARIO reagents to maintain traceability.
Is third-party certification available for method validation?
ChemTron provides ISO/IEC 17025-accredited certificate of conformance for both instrument and reagent systems, including uncertainty budgets for reported COD values.
How often does the optical system require recalibration?
Photometric stability is verified daily using built-in reference filters; full factory recalibration is recommended every 12 months or after 5,000 measurements, whichever occurs first.
Are replacement parts and service support available globally?
Yes—ChemTron maintains authorized service centers in North America, EMEA, and APAC regions, with spare parts inventory for optics, power modules, and display assemblies held under ISO 9001-certified logistics protocols.