Dr-T9904 Total Nitrogen Analyzer by DoctorWater
| Brand | DoctorWater |
|---|---|
| Origin | Hunan, China |
| Model | Dr-T9904 |
| Measurement Method | Photometric (UV-Vis Spectrophotometry) |
| Range | 0–100 mg/L TN |
| Accuracy | ≤ ±5% |
| Detection Limit | 0 mg/L (as reported |
| Resolution | 0.001 Abs |
| Wavelength Range | 340–900 nm |
| Wavelength Accuracy | ±1 nm |
| Wavelength Repeatability | <0.2 nm |
| Spectral Bandwidth | 4 nm |
| Transmittance Error | ±0.5% |
| Transmittance Repeatability | ≤0.2% T |
| Optical Stability | ≤±0.005 Abs/20 min |
| Light Source | Imported Cold LED (Lifespan >100,000 h) |
| Display | 8-inch HD Capacitive Touchscreen |
| Sample Holders | Rotatable Cuvette Holder (360°), Dual Cuvette Positions (10 mm & 30 mm pathlength), 4 Independent Digital Electrode Ports |
| Calibration | Single- and Multi-point Standard Curve Generation |
| Preloaded Curves | 1,000 Method-Specific Calibration Curves |
| Data Storage | 1,000,000 Records with Timestamp, Operator ID, and Batch Traceability |
| Output | Thermal Printer, USB Export (CSV), On-screen Graphing & Filtering |
| Housing | Corrosion-Resistant ABS Enclosure |
| Dimensions | 392 × 315 × 170 mm |
| Weight | 4.4 kg |
Overview
The Dr-T9904 Total Nitrogen Analyzer by DoctorWater is a benchtop photometric analyzer engineered for precise, standardized quantification of total nitrogen (TN) in aqueous matrices using UV-Vis spectrophotometry—specifically the alkaline potassium persulfate digestion followed by absorbance measurement at 220 nm and 275 nm (dual-wavelength correction per ISO 11905-1 and HJ 636-2012). Unlike single-parameter instruments, the Dr-T9904 integrates optical detection with digital electrochemical sensing capability, enabling concurrent or sequential analysis of TN, ammonia nitrogen, nitrate, nitrite, total phosphorus, COD, turbidity, pH, conductivity, ORP, dissolved oxygen, and over 100 additional water quality parameters. Its modular optical architecture employs a fiber-optic detection system coupled with a high-stability cold LED light source, ensuring minimal thermal drift and long-term photometric fidelity across extended operational cycles. Designed for compliance-driven environments, the instrument supports traceable calibration workflows and audit-ready data logging aligned with GLP principles.
Key Features
- Triple-mode sample introduction: 360° rotatable cuvette holder to eliminate path-length variance and tube-to-tube optical heterogeneity; dual fixed-position cuvette slots accommodating both 10 mm and 30 mm pathlength cells; and four independent digital electrode ports for simultaneous potentiometric or amperometric measurements.
- 8-inch HD capacitive touchscreen with adjustable brightness, supporting intuitive gesture navigation and real-time spectral preview during method selection.
- Optical system certified to ISO 9001-manufactured tolerances: wavelength accuracy ±1 nm, repeatability <0.2 nm, and spectral bandwidth fixed at 4 nm—critical for resolving overlapping absorbance peaks in complex digested samples.
- Preloaded library of 1,000 validated calibration curves—including EPA 353.2, ISO 11905-1, HJ 636-2012, and GB/T 11894–1989—enabling immediate deployment without manual curve derivation.
- Onboard data integrity safeguards: automatic flagging of out-of-range results (user-defined thresholds), real-time optical stability monitoring (≤±0.005 Abs/20 min), and hardware-based timestamped storage of 1 million records with operator ID and batch metadata.
- Thermal printer integration and USB mass-storage export (CSV format) compliant with laboratory information management system (LIMS) ingestion protocols.
Sample Compatibility & Compliance
The Dr-T9904 accommodates raw and pretreated liquid samples from diverse environmental and industrial sources—including municipal wastewater, surface water, groundwater, industrial effluents (e.g., electroplating, pulp & paper, pharmaceutical manufacturing), aquaculture systems, and boiler feedwater. All digestion and measurement protocols adhere to internationally recognized standards: TN determination follows ISO 11905-1 (water quality — determination of nitrogen compounds — part 1: total nitrogen after acid digestion), while optical performance conforms to ISO 7027 (turbidity) and EN ISO 15705 (COD by dichromate). The system supports 21 CFR Part 11-compliant user access control when deployed with optional network authentication modules, and its audit trail functionality satisfies GLP/GMP documentation requirements for regulated laboratories.
Software & Data Management
The embedded firmware provides full method lifecycle management—from calibration verification (single/multi-point, bracketing, and linearity assessment) to QC sample tracking and recovery calculation. Each measurement session logs absorbance spectra, raw transmittance values, calculated concentrations, and deviation flags against preconfigured acceptance criteria. Data export via USB includes full metadata (date/time, operator ID, method ID, curve version, and instrument serial number), facilitating seamless integration into LIMS or ELN platforms. Optional cloud synchronization enables remote diagnostics and firmware updates without local IT intervention. All stored records are immutable post-acquisition unless explicitly overwritten under administrator privilege—ensuring data integrity for regulatory review.
Applications
- Environmental monitoring stations performing routine TN surveillance per national water quality standards (e.g., China’s Class III–V surface water criteria).
- Municipal wastewater treatment plants conducting process control at influent, bioreactor, and effluent points to verify nitrification/denitrification efficiency.
- Industrial QA/QC labs validating discharge compliance with local permit limits (e.g., textile dyeing effluents, semiconductor rinse waters).
- Academic and research institutions executing nutrient cycling studies, eutrophication modeling, or method validation intercomparisons.
- Third-party testing laboratories accredited to CNAS/ISO/IEC 17025 requiring documented uncertainty budgets and traceable reference material usage.
FAQ
What digestion method is required for total nitrogen analysis on the Dr-T9904?
The instrument itself does not perform digestion; it measures absorbance post-digestion. Users must apply standardized alkaline potassium persulfate oxidation (per ISO 11905-1 or HJ 636-2012) using external autoclaves or block digesters prior to photometric reading.
Can the Dr-T9904 be used for field deployment?
It is designed as a benchtop laboratory instrument (4.4 kg, AC-powered) and is not IP-rated for outdoor or mobile use. Portable variants require separate validation and are not covered under this model specification.
Is English language support available for the interface?
Yes—the system supports configurable UI localization, including full English translation, which can be enabled during initial setup or via administrator menu.
How is calibration traceability maintained?
Each calibration event is timestamped, associated with standard lot numbers, and archived with slope/intercept values and R² statistics. Reference standards must be NIST-traceable or certified reference materials (CRMs) meeting ISO Guide 34 requirements.
Does the instrument meet FDA or EU regulatory requirements for pharmaceutical water testing?
While not pre-certified for USP or Ph. Eur. 2.2.44, the Dr-T9904’s optical specifications and data handling architecture are compatible with validation protocols required for purified water and WFI monitoring when operated within a qualified analytical method framework.
