Lohan COD Automatic Titrator LH-JA100

Overview

The Lohan COD Automatic Titrator LH-JA100 is a dedicated, high-precision electronic titrator engineered for compliant implementation of the dichromate oxidation method (COD_Cr) as specified in HJ 828–2017 and GB 11914–1989. It operates on optical endpoint detection—utilizing RGB colorimetric recognition calibrated to the characteristic green-to-brown transition of the ferroin indicator during titration with ammonium ferrous sulfate (AFS). Unlike generic potentiometric or pH-based titrators, the LH-JA100 embeds a purpose-built algorithmic engine that interprets chromatic shifts across standardized color gradients, enabling unambiguous endpoint identification without manual intervention. This architecture eliminates subjectivity inherent in visual titration while maintaining full alignment with regulatory wet-chemistry protocols required for environmental wastewater compliance testing.

Key Features

• Optical endpoint detection via RGB sensor array with adaptive color-step discrimination—trained specifically on the Fe²⁺/Fe³⁺ redox transition in the presence of 1,10-phenanthroline (ferroin)
• Automated reagent dispensing: precise delivery of ferroin indicator and ammonium ferrous sulfate solution; optional single-reagent mode (AFS only) to minimize rinse volume and cross-contamination risk
• Dual-range support: programmable calibration for low-range (16–50 mg/L COD) and high-range (50–700 mg/L COD), with automatic dilution factor compensation where integrated with upstream digestion systems
• Chloride tolerance up to 2000 mg/L Cl⁻: robust signal processing accommodates mild turbidity without false endpoint triggering
• Titration resolution: 0.02 mL per dispense step; volumetric accuracy ≤ ±0.01 mL (verified per ISO 8655-6 for piston burettes)
• Integrated magnetic stirrer with variable speed control (100–800 rpm) ensures homogeneous reaction kinetics and complete oxidant–reductant mixing
• Corrosion-resistant fluid path: all wetted components constructed from borosilicate glass or PTFE—fully compatible with hot sulfuric acid (H₂SO₄), Ag₂SO₄, and K₂Cr₂O₇ solutions
• Onboard data retention: non-volatile memory stores up to 2000 test records with timestamp, operator ID, sample ID, blank values, and raw titrant volume

Sample Compatibility & Compliance

The LH-JA100 is validated for aqueous matrices including municipal wastewater, industrial effluent, surface water, and digested sludge filtrates. Its optical detection system remains stable under conditions typical of post-digestion samples—elevated temperature residuals (<60 °C), suspended solids ≤100 mg/L, and moderate chloride interference. The instrument meets functional requirements outlined in HJ 828–2017 Annex B (automatic titration validation) and supports audit-ready documentation for GLP and ISO/IEC 17025-accredited laboratories. All reagent delivery events, endpoint decisions, and manual overrides are time-stamped and logged—enabling traceability in accordance with FDA 21 CFR Part 11 principles when paired with validated LIMS integration.

Software & Data Management

Data export is supported via USB 2.0 interface (CSV format) and direct thermal printing (via integrated 58-mm thermal printer). The onboard interface permits user-defined blank management (up to four stored blanks), parallel sample sequencing (five positions), and real-time statistical evaluation (mean, SD, CV%). Abnormal titration curves trigger audible and visual alerts—including over-titration, insufficient color development, or inconsistent baseline drift—prompting operator review prior to result finalization. No proprietary software installation is required; exported datasets conform to ASTM D129–18 and ISO 6060 standard reporting templates.

Applications

• Routine COD_Cr analysis in wastewater treatment plants (WWTPs) for process control and discharge compliance
• Environmental monitoring labs conducting EPA Method 410.4-equivalent testing under national regulatory frameworks
• Research institutions performing method validation studies comparing automated vs. manual titration precision (RSD <1.2% at 100 mg/L COD)
• Academic teaching labs requiring reproducible, hands-off demonstration of redox titration fundamentals
• Integration with Lohan’s LH-F510/F112/F108/6F intelligent reflux digesters to form a closed-loop COD_Cr workflow—from digestion to endpoint quantification

FAQ

Does the LH-JA100 comply with HJ 828–2017 for automatic titration verification?

Yes—the instrument satisfies Clause 7.3.2 of HJ 828–2017, including endpoint repeatability (≤0.05 mL RSD across five replicates) and recovery accuracy (95–105% for certified reference materials).
Can it be used with non-Lohan digestion systems?

Yes—provided digested samples meet standard cooling, dilution, and clarity specifications; manual sample loading is supported.
Is the RGB sensor calibrated against NIST-traceable color standards?

Calibration uses internal reference spectra aligned to CIE 1931 xyY color space; factory calibration certificates include deviation metrics against ISO 17025-accredited spectrophotometric references.
What maintenance intervals are recommended for long-term accuracy?

Burette piston lubrication and optical window cleaning every 3 months; annual verification of volumetric delivery against gravimetric standards per ISO 8655-6.
Does it support remote diagnostics or firmware updates?

Firmware updates are performed locally via USB drive; remote access is not implemented to preserve data integrity and regulatory isolation requirements.