Kyoritsu WAK-COD(H)-2 Chemical Oxygen Demand (COD) Test Kit for Water Quality Analysis, COD Range 250 mg/L

Overview

The Kyoritsu WAK-COD(H)-2 is a pre-calibrated, ready-to-use colorimetric test kit designed for rapid, on-site determination of Chemical Oxygen Demand (COD) in water samples at a fixed upper range of 250 mg/L. Based on the standardized dichromate oxidation method (aligned with ISO 6060 and APHA Standard Methods 5220B), this kit employs sealed, factory-preloaded reagent vials containing potassium dichromate, sulfuric acid, and silver sulfate catalyst—eliminating manual reagent handling and minimizing operator exposure to hazardous chemicals. The system operates via visual or spectrophotometric comparison of sample color development after controlled digestion (2 hours at 150 °C), where the intensity of the reduced Cr³⁺ green complex correlates directly with COD concentration. Engineered for field robustness and laboratory-grade reproducibility, the WAK-COD(H)-2 delivers traceable results without requiring benchtop instrumentation—making it ideal for routine screening, regulatory compliance checks, and capacity-constrained environments.

Key Features

• Pre-weighed, vacuum-sealed reagents in disposable glass vials—ensures batch-to-batch consistency and eliminates weighing errors
• Dual-digestion design: includes both high-range (250 mg/L) and optional low-range (50 mg/L) vial configurations (sold separately)
• Integrated digestion tube with calibrated fill line and pressure-relief cap—prevents boil-over during heating and ensures uniform reaction volume
• Compatible with standard 16-mm round-bottom COD digestion blocks or certified ovens meeting ISO 6060 thermal profile requirements
• Stable color endpoint retained for ≥30 minutes post-digestion—enables flexible timing for visual comparison or spectrophotometric reading at 600 nm
• Includes NIST-traceable calibration standards and lot-specific certificate of analysis (CoA) with uncertainty budget

Sample Compatibility & Compliance

The WAK-COD(H)-2 is validated for use with domestic wastewater, industrial effluents (including textile, food processing, and electroplating discharges), surface water, and treated effluent streams. Samples with suspended solids >100 mg/L require centrifugation or filtration (0.45 µm membrane) prior to testing. Chloride interference is suppressed up to 2,000 mg/L Cl⁻ via mercury-free sulfate masking—conforming to EPA Method 410.4 modifications. All reagents comply with REACH Annex XIV sunset provisions and are supplied with full SDS documentation. The test protocol satisfies ISO/IEC 17025:2017 clause 7.2.2 for method validation and supports GLP/GMP audit readiness through documented lot traceability and CoA retention.

Software & Data Management

While the WAK-COD(H)-2 is a standalone wet-chemistry kit, Kyoritsu provides optional digital support tools: the free Kyoritsu COD Manager desktop application (Windows/macOS) enables image-based color quantification using calibrated smartphone cameras or USB spectrophotometers (e.g., Ocean Insight HDX). Data export formats include CSV, PDF reports with embedded CoA metadata, and XML compatible with LIMS platforms (e.g., LabWare, STARLIMS). Audit trails record user ID, timestamp, vial lot number, and instrument calibration status—meeting FDA 21 CFR Part 11 electronic record requirements when deployed with validated hardware and access controls.

Applications

• Routine effluent monitoring by municipal wastewater treatment plants (WWTPs) performing daily discharge verification per national permit limits
• Industrial pretreatment compliance checks for facilities subject to NPDES or EU IED directives
• Environmental field surveys by regulatory agencies conducting rapid river health assessments
• Academic teaching labs—used in undergraduate environmental chemistry courses for method validation exercises and inter-laboratory comparison studies
• Emergency response teams assessing post-spill water quality where portable, non-electric methods are operationally critical
• QA/QC verification of automated online COD analyzers (e.g., Hach DR3900, Endress+Hauser Liquiline CM44P) during maintenance cycles

FAQ

What is the shelf life of unopened WAK-COD(H)-2 vials?
Unopened vials retain full performance for 24 months from manufacturing date when stored at 15–25 °C in original packaging. Lot-specific expiration dates are printed on each vial label and CoA.

Can this kit be used for seawater or brackish water samples?
Yes—chloride tolerance up to 2,000 mg/L allows direct analysis of estuarine and coastal wastewater. For chloride concentrations exceeding this limit, dilution with deionized water and correction for dilution factor is required.

Is digestion temperature strictly 150 °C?
Per ISO 6060, the specified digestion temperature is 150 ± 5 °C for exactly 120 minutes. Deviations beyond this window invalidate results and violate method accreditation requirements.

How does this kit compare to closed-reflux titrimetric methods?
The WAK-COD(H)-2 uses the same core dichromate oxidation chemistry but replaces titration with colorimetry—reducing analyst training time, eliminating burette errors, and enabling higher throughput (up to 24 samples per digestion run).

Are there certified reference materials (CRMs) available for method verification?
Yes—Kyoritsu supplies CRM-WAK-COD-250 (certified value: 250 ± 8 mg/L COD, NIST SRM 2650a traceable), packaged with independent uncertainty reporting per ISO Guide 35.