Oakton C-103 / C-105 / C-201 / C-301 / C-401 Portable Colorimeters

Overview

The Oakton C-Series portable colorimeters (C-103, C-105, C-201, C-301, and C-401) are precision optical instruments engineered for reliable, field-deployable quantitative analysis of water quality parameters using standardized colorimetric methods. These devices operate on the principle of Beer-Lambert absorption spectroscopy at a fixed wavelength of 525 nm—optimized for high sensitivity in DPD-based chlorine assays and other EPA-compliant chromogenic reactions. Each unit integrates a stable LED light source and a calibrated silicon photodiode detector to deliver consistent photometric performance across variable ambient conditions. Designed for operational robustness in demanding environments—including municipal water treatment facilities, swimming pool service operations, environmental monitoring labs, and wastewater management sites—the C-Series units meet IP67 ingress protection standards, ensuring full dust resistance and temporary submersion tolerance. Their microprocessor-controlled architecture enables automatic range selection, real-time error diagnostics with context-aware resolution guidance, and programmable auto-shutdown to maximize battery longevity without compromising measurement repeatability.

Key Features

• Fixed-wavelength photometry at 525 nm (±1 nm tolerance), optimized for DPD-based chlorine, ozone, and cyanuric acid assays per U.S. EPA and ASTM protocols
• High-precision absorbance measurement capability from 0 to 2.5 AU with ±0.0015 AU accuracy—enabling trace-level detection of residual disinfectants
• IP67-rated enclosure for use in humid, outdoor, or splash-prone settings without protective housing
• Intelligent firmware with self-diagnostic routines that identify common anomalies (e.g., cuvette misalignment, low battery, reagent depletion) and provide actionable corrective prompts
• Auto-ranging functionality eliminates manual scale selection, reducing operator error during multi-range measurements (e.g., free chlorine: 0.01–1.99 ppm and 2.0–6.0 ppm)
• Long-life power system powered by four standard AA alkaline batteries, delivering up to 3500 hours of continuous operation under typical usage cycles
• Ergonomic handheld form factor (16 × 7 × 5 cm) with intuitive push-button interface and backlit LCD display for low-light field applications

Sample Compatibility & Compliance

The C-Series supports aqueous samples across diverse water matrices: potable water, swimming pool water, wastewater effluents, groundwater, and treated process streams. All models comply with method-specific regulatory frameworks, including U.S. EPA Method 334.0 for free and total chlorine determination via DPD oxidation, ASTM D1253/D3370 for residual chlorine quantification, ASTM D5463 for dissolved ozone, ASTM D1067 for pH colorimetric assessment, and ASTM D5682 for cyanuric acid analysis. Reagent compatibility is strictly validated per lot number; all included test kits (e.g., 35645-64 for free chlorine, 35645-66 for total chlorine, 35645-62 for cyanuric acid) are manufactured to ISO 17025-accredited specifications and traceable to NIST-standard reference materials. The 10 mL sample volume requirement ensures sufficient pathlength for reproducible absorbance readings while minimizing reagent consumption.

Software & Data Management

While the C-Series operates as a standalone instrument with no onboard data logging or Bluetooth/Wi-Fi connectivity, its design fully supports GLP-compliant documentation workflows. Each measurement cycle generates a timestamped result displayed on-screen with configurable unit output (ppm, mg/L, or pH units). Users may record results manually into laboratory notebooks or integrate readings into LIMS via standardized reporting templates. Calibration verification is performed using factory-supplied neutral density filters and certified reference standards; calibration status is retained in non-volatile memory and persists through battery replacement. Firmware updates—distributed exclusively through authorized Oakton service centers—maintain alignment with evolving EPA and ASTM revision cycles and include audit-trail enhancements supporting FDA 21 CFR Part 11 readiness when used within validated SOPs.

Applications

• Routine monitoring of free and total chlorine residuals in municipal drinking water distribution systems and recreational water venues
• Verification of ozone dosing efficacy in bottled water production and tertiary wastewater disinfection processes
• Quantitative assessment of cyanuric acid stabilization levels in chlorinated swimming pools to prevent UV degradation of hypochlorous acid
• Field-based pH screening in decentralized water quality surveillance programs where electrode-based meters are impractical
• Environmental compliance sampling for NPDES permit reporting, particularly where rapid-turnaround colorimetric screening precedes confirmatory ICP or titrimetric analysis
• Quality assurance testing in chemical manufacturing facilities producing chlorine-based biocides and sanitizers

FAQ

What regulatory methods do the Oakton C-Series colorimeters support?
The instruments are validated for U.S. EPA Method 334.0 (chlorine), ASTM D1253/D3370 (residual chlorine), ASTM D5463 (ozone), ASTM D1067 (pH), and ASTM D5682 (cyanuric acid).
Do these colorimeters require annual recalibration?
No scheduled recalibration is required; however, users must verify photometric performance before each analytical session using supplied blank cuvettes and reference standards per ASTM E275.
Are reagents supplied with traceability documentation?
Yes—each reagent kit (e.g., 35645-64, 35645-66, 35645-62) includes a Certificate of Analysis referencing NIST-traceable standards and batch-specific stability data.
Can the C-401 measure cyanuric acid independently of chlorine parameters?
Yes—the C-401 provides dedicated assay channels for cyanuric acid (5–90 ppm), free/total chlorine, and pH, allowing concurrent but independent analysis without cross-parameter interference.
Is the IP67 rating maintained when the battery compartment is opened?
IP67 protection applies only when all seals—including the battery door gasket—are fully engaged and undamaged; routine inspection of sealing surfaces is recommended per maintenance schedule.