Lamotte Color Q Footbath Chlorine Analyzer
| Brand | Lamotte |
|---|---|
| Origin | USA |
| Model | Color Q |
| Detection Parameters | Free Chlorine (0–10 mg/L), Total Chlorine (Low Range: 0–10 mg/L |
| High Range | 0–750 mg/L) |
| Resolution | 0.01 mg/L |
| Test Capacity | 50 tests per reagent set (low range), 50 tests per high-range liquid reagent vial |
| Optical Design | Dual-wavelength photometric system |
| Reagent Format | DPD effervescent tablets (low range), stabilized liquid DPD reagent (high range) |
| Enclosure Rating | IP57 |
| Display | Backlit digital LCD |
Overview
The Lamotte Color Q Footbath Chlorine Analyzer is a portable, field-deployable photometer engineered for precise quantification of free chlorine and total chlorine in recreational water systems—specifically designed for compliance monitoring in footbaths, splash pads, and pre-entry hygiene stations. It operates on the standardized N,N-diethyl-p-phenylenediamine (DPD) colorimetric method, where chlorine oxidizes DPD to form a stable magenta-colored compound proportional to concentration. The instrument employs a dual-wavelength optical architecture: one wavelength measures the primary absorbance peak of the DPD-chlorine complex (~515 nm), while the second serves as a reference channel to compensate for turbidity, sample color interference, and cuvette path-length variation. This design enhances measurement robustness across variable water matrices commonly encountered in high-traffic public facilities—where organic load, pH fluctuations, and residual oxidants may otherwise compromise accuracy.
Key Features
- Dual-wavelength photometric detection system with temperature-compensated LED light sources and precision silicon photodetectors
- Pre-calibrated, factory-validated method-specific firmware for both free chlorine (ASTM D1253-22 compliant) and total chlorine (APHA 4500-Cl G)
- Integrated reagent management: low-range measurements use individually sealed DPD effervescent tablets (each tablet delivers exact 0.05 mg DPD dose); high-range total chlorine analysis utilizes metered liquid reagent dispensed via calibrated dropper
- IP57-rated enclosure—dust protected and submersible up to 1 m for 30 minutes—enabling reliable operation in humid, splash-prone environments
- Backlit, 3.2-inch monochrome LCD display with intuitive menu navigation and real-time graphical feedback during measurement cycles
- Built-in battery diagnostics and auto-shutdown after 10 minutes of inactivity to extend alkaline AA battery life (>2,000 tests per set)
Sample Compatibility & Compliance
The Color Q is validated for use with clarified or mildly turbid aqueous samples typical of footbath recirculation systems (NTU < 25). It accommodates standard 10 mL glass or polystyrene cuvettes (10 mm path length) and includes a dedicated cuvette cleaning brush and calibration verification standard (1.0 mg/L Cl₂ certified reference solution). Method performance meets EPA Guidance Manual for Disinfectants (2021) requirements for secondary disinfection monitoring and aligns with CDC Model Aquatic Health Code (MAHC) Section 6.3.2.2 for footbath residual chlorine verification. Instrument traceability supports GLP documentation workflows through optional CSV export (via USB-C interface) and complies with ISO/IEC 17025:2017 clause 7.7 for measurement uncertainty estimation when used with certified reagents and calibrated pipettes.
Software & Data Management
While the Color Q operates as a standalone photometer without onboard data logging, it supports audit-ready documentation via its USB-C port. When connected to a Windows-based PC running Lamotte’s free LogBook Pro software (v3.2+), users can download timestamped test records—including sample ID, operator code, measured value, range selected, and reagent lot number. Each record contains embedded metadata required for FDA 21 CFR Part 11-compliant electronic records when paired with institutional electronic signature protocols. Firmware updates are distributed quarterly via Lamotte’s secure customer portal and include method revisions aligned with latest APHA Standard Methods amendments.
Applications
- Routine verification of footbath chlorine residuals in commercial aquatic facilities, water parks, and spa complexes
- Validation of disinfectant contact time efficacy during facility opening/closing procedures
- Third-party inspection support for health department audits under state sanitary codes (e.g., NY State Sanitary Code Title 10, Subpart 6-1)
- Training tool for lifeguard and maintenance staff on chlorine chemistry fundamentals and measurement best practices
- Supplemental testing in conjunction with online amperometric sensors to verify sensor drift or calibration integrity
FAQ
Does the Color Q require annual calibration verification?
Yes—Lamotte recommends verifying photometric accuracy quarterly using the included 1.0 mg/L Cl₂ standard and performing full recalibration annually per ISO 8466-1:2022 guidelines.
Can the same DPD tablet be used for both free and total chlorine tests?
No—free chlorine uses the standard DPD tablet; total chlorine requires addition of potassium iodide (KI) prior to tablet dissolution, which is supplied separately in the high-range kit.
Is the instrument compatible with non-Lamotte reagents?
Lamotte does not validate performance with third-party reagents; use of non-certified DPD formulations may invalidate MAHC compliance documentation and introduce interferences from stabilizer additives.
What is the minimum detectable concentration for free chlorine?
The instrument achieves a method detection limit (MDL) of 0.02 mg/L free chlorine at 99% confidence (n=7 replicates, ASTM D3852-20), consistent with reported resolution of 0.01 mg/L.
How is sample turbidity addressed during measurement?
The dual-wavelength algorithm inherently corrects for turbidity-induced scatter up to 25 NTU; samples exceeding this threshold must be filtered via 0.45 µm membrane prior to analysis per APHA 2540 B.
