Shenchanghong CN-201C/D COD & Ammonia-N Analyzer

Overview

The Shenchanghong CN-201C/D is a dual-parameter laboratory water quality analyzer engineered for precise, routine quantification of Chemical Oxygen Demand (COD) and Ammonia-Nitrogen (NH₃-N) in municipal wastewater, industrial effluents, and surface water samples. It implements two standardized spectrophotometric methodologies: rapid digestion followed by dichromate-based optical detection for COD measurement, and Nesslerization for ammonia-nitrogen determination. The system separates optical measurement and thermal digestion into independent modules—host analyzer and external digester—to eliminate thermal crosstalk and ensure long-term photometric stability. Its optical architecture utilizes high-brightness, low-drift cold-light sources with optimized optical path design (enhanced in the CN-201D variant), delivering consistent performance across extended operational cycles. Designed for compliance with national and international water analysis protocols—including HJ/T 399–2007 (COD) and HJ 535–2009 (NH₃-N)—the instrument supports method validation, QC/QA workflows, and regulatory reporting in environmental testing laboratories.

Key Features

• Modular architecture: Physically decoupled host analyzer and temperature-controlled digester (DIS-16B standard; DIS-20B/25B/36B optional) prevents heat-induced baseline drift in optical measurements.
• Precision thermal control: PID-regulated digester with ±0.5 °C accuracy over 0–200 °C range; programmable digestion time (1–9999 min) enables method flexibility beyond standard COD protocols.
• High-resolution human interface: 5-inch capacitive touchscreen (800×480) with bilingual (English/Chinese) GUI, intuitive icon-driven navigation, and one-touch system recovery function.
• Extended data management: CN-201C stores up to 300 calibration curves and 1000 test records; CN-201D expands capacity to 3500 curves and 100,000 records—supporting multi-user labs and longitudinal trend analysis.
• Robust optical system: Imported long-life cold-light source, minimized stray light design, and real-time absorbance drift monitoring (<0.002 A/20 min) ensure metrological reliability per ISO/IEC 17025 requirements.
• Regulatory-ready connectivity: USB 2.0 interface enables secure export of raw data, calibration logs, and audit trails to external PCs for GLP-compliant documentation and LIMS integration.

Sample Compatibility & Compliance

The CN-201C/D accepts standard 16 mm glass or quartz digestion tubes (compatible with all DIS-series digesters) and accommodates sample volumes of 2.5–5.0 mL. It meets key Chinese environmental standards: HJ/T 399–2007 for COD determination and HJ 535–2009 for ammonia-nitrogen analysis. Its chloride interference tolerance of ≤2000 mg/L Cl⁻ (for COD) aligns with typical wastewater matrix challenges. While not certified to ISO 6060 (COD) or ISO 7150-1 (NH₃-N) out-of-the-box, its measurement principle, repeatability (≤±3% RSD), and traceable calibration protocol support laboratory validation per ISO/IEC 17025:2017 Clause 7.7. The instrument’s firmware architecture allows user-defined method configuration and parameter logging—facilitating internal SOP development and third-party audit readiness.

Software & Data Management

Embedded firmware provides full method setup, curve calibration (linear, polynomial, or multi-point non-linear), and automatic concentration calculation. All operations—including date/time stamping, operator ID entry (via on-screen keyboard), and result validation—are logged with immutable timestamps. USB data export generates CSV files containing sample ID, measured absorbance, calculated concentration, calibration curve ID, digestion parameters, and QC flag status. No proprietary software is required for data review; exported files are compatible with Microsoft Excel, LabArchives, and most LIMS platforms. Audit trail functionality satisfies basic FDA 21 CFR Part 11 expectations for electronic records when paired with institutional procedural controls (e.g., password-protected access, defined user roles).

Applications

• Routine wastewater treatment plant (WWTP) influent/effluent monitoring per discharge permit requirements.
• Industrial pretreatment compliance verification for electroplating, pharmaceutical, food processing, and textile facilities.
• Environmental monitoring station QA/QC for surface water bodies (rivers, lakes, reservoirs).
• Educational laboratories conducting AP Environmental Science or undergraduate analytical chemistry experiments.
• Contract testing labs performing batch analysis under CNAS-accredited scopes (with validated methods).

FAQ

What digestion methods does the CN-201C/D support?
It supports rapid closed-vessel digestion at 165 °C for 15 minutes (COD) and room-temperature Nesslerization (NH₃-N), both compliant with Chinese EPA standard methods.
Can the instrument be used for total nitrogen or phosphorus analysis?
No—the CN-201C/D is dedicated exclusively to COD and ammonia-nitrogen. Total nitrogen requires alkaline persulfate digestion and UV spectrophotometry; phosphorus requires ascorbic acid/molybdate colorimetry—neither is supported.
Is the digester temperature calibrated traceably?
The DIS-series digesters include factory-calibrated Pt100 sensors with documented uncertainty; users may perform periodic verification using NIST-traceable reference thermometers.
How is data integrity maintained during power interruption?
All active measurements and calibration data reside in non-volatile flash memory; unsaved results prior to interruption are retained in RAM with battery backup (≥30 sec hold-up time).
Does the instrument support external printer connectivity?
Yes—via USB-to-serial adapters compatible with ESC/POS command-set thermal printers (e.g., Star SP200 series); direct parallel or Bluetooth printing is not supported.