Leichi DGB-421 Portable Water Colorimeter

Overview

The Leichi DGB-421 Portable Water Colorimeter is a field-deployable optical instrument engineered for rapid, reliable quantification of color in potable water, wastewater, and process streams using the internationally recognized Platinum-Cobalt (Pt-Co) method. Based on spectrophotometric absorption measurement at a fixed wavelength (typically ~455 nm), the device compares sample absorbance against traceable Pt-Co reference standards defined in GB/T 5750.4–2023—the Chinese national adaptation of ISO 7887 and ASTM D1209. Unlike subjective visual comparison methods, the DGB-421 delivers objective, numerical results expressed in Platinum-Cobalt Units (PCU), directly equivalent to Hazen units and mg Pt/L. Its compact form factor, ruggedized housing, and dual-power architecture make it suitable for routine monitoring in resource-constrained environments—including remote sampling sites, mobile laboratories, and on-site QA/QC audits—without sacrificing metrological integrity.

Key Features

• Optical system calibrated against certified Pt-Co standard solutions per GB/T 5750.4–2023, ensuring traceability to national reference materials
• High-contrast monochrome LCD display with backlight for legibility under variable ambient lighting conditions
• No reagent consumption required during routine operation—eliminates chemical handling, storage, and disposal concerns
• Dual calibration capability: user-accessible zero-point (deionized water) and full-scale (50 PCU standard) adjustment to maintain long-term stability
• IP65-rated enclosure providing dust-tight integrity and protection against low-pressure water jets—validated for outdoor and industrial deployment
• Integrated data management: stores up to 200 measurement records with timestamp, enabling offline review and manual export via USB interface
• Intelligent power management: auto-shutdown after 10 minutes of inactivity; real-time battery level indicator displayed on startup and during operation

Sample Compatibility & Compliance

The DGB-421 is validated for use with clarified, non-turbid aqueous samples meeting turbidity thresholds <5 NTU (as specified in GB/T 5750.4). It is not intended for highly colored, opaque, or suspended-solid-laden matrices without prior filtration (e.g., 0.45 µm membrane). The instrument conforms to the measurement principle and reporting requirements of GB/T 5750.4–2023, which aligns with ISO 7887:2011 and ASTM D1209–18 for color determination in drinking water and related matrices. While not FDA 21 CFR Part 11-compliant out-of-the-box (lacking electronic audit trail and user authentication), its calibration log and stored data support GLP-aligned documentation when paired with laboratory notebooks and procedural SOPs.

Software & Data Management

The DGB-421 operates as a standalone embedded system with no external software dependency. All firmware logic—including absorbance-to-PCU conversion, calibration interpolation, and memory management—is executed internally. Measurement data (PCU value, date/time stamp, calibration status flag) are retained in non-volatile memory and can be reviewed sequentially on-device. USB connectivity serves exclusively for power input and does not support data download or firmware updates—a design choice prioritizing field robustness over digital integration. For regulated environments requiring electronic records, users must manually transcribe results into LIMS or ELN systems compliant with ALCOA+ principles.

Applications

• Routine color verification in municipal drinking water treatment plants pre- and post-filtration
• Compliance screening for effluent discharge permits (e.g., local environmental protection bureau requirements)
• In-process monitoring of purified water in pharmaceutical manufacturing (USP reference method alignment)
• Quality control of bottled water, soft drinks, and brewing wort clarity assessment
• Field-based environmental surveys assessing tannin-stained surface waters or humic acid contamination
• Educational laboratories demonstrating standardized colorimetric analysis protocols

FAQ

What color standard does the DGB-421 implement?
It implements the Platinum-Cobalt (Pt-Co) scale per GB/T 5750.4–2023, with results reported in PCU—numerically identical to Hazen units and mg Pt/L.
Can the instrument measure samples with high turbidity?
No. Turbidity >5 NTU interferes with absorbance measurement; filtration through a 0.45 µm membrane is required prior to analysis.
Is calibration traceable to national standards?
Yes—calibration uses Pt-Co reference solutions certified to GBW(E) 130242 or equivalent, with documentation supporting traceability to NIM (National Institute of Metrology, China).
Does the device support data export to CSV or Excel?
No. Data must be manually recorded; the USB port provides power only and lacks data communication capability.
What is the recommended recalibration frequency?
Zero calibration before each measurement session; full-scale calibration every 30 days or after exposure to extreme temperature/humidity shifts.