Hengmei HM-DN2 Automated Kjeldahl Nitrogen Determinator
| Brand | Hengmei |
|---|---|
| Origin | Shandong, China |
| Manufacturer Type | Direct Manufacturer |
| Instrument Type | Automated Kjeldahl Nitrogen Determinator |
| Automation Level | Fully Automated |
| Nitrogen Measurement Range | 0.1–240.0 mg N |
| Repeatability | ≤0.5% RSD (parallel determinations) |
| Sample Weight Capacity | ≤8.0 g (solid), ≤30.0 mL (liquid) |
| Nitrogen Recovery Rate | 99–101% |
| Power Consumption | ≤1500 W |
Overview
The Hengmei HM-DN2 Automated Kjeldahl Nitrogen Determinator is a fully integrated analytical system engineered for precise, traceable, and high-throughput quantification of total nitrogen content in organic matrices—based on the classical Kjeldahl digestion–distillation–titration principle standardized in ISO 8968-1, AOAC 981.10, and USP <467>. The instrument automates the complete sequence: post-digestion alkalization, steam distillation under controlled pressure and temperature, boric acid absorption, and potentiometric or colorimetric endpoint detection via high-resolution optical sensing. Unlike semi-automated systems, the HM-DN2 performs reagent dosing (NaOH, boric acid, diluent, condensate water), distillation initiation/termination, condensate flow regulation, reaction cup evacuation, and multi-cycle rinsing—all under closed-loop programmable logic control. Its architecture ensures stoichiometric completeness of ammonia liberation and quantitative capture, delivering data compliant with GLP and GMP documentation requirements when paired with audit-trail-enabled software.
Key Features
- 10.1-inch capacitive touchscreen running Android 10 OS, supporting intuitive method setup, real-time process visualization, and multilingual UI configuration.
- Fully automated fluid handling: independent peristaltic pumps deliver NaOH, boric acid solution (4%), diluent, and distilled water with volumetric accuracy ±1.0% at 1–50 mL range.
- Integrated safety subsystems: evaporator water-level sensor with dry-run cutoff, real-time condensate flow monitoring (1.5 L/min nominal, low-flow alarm threshold at 1.0 L/min), cold-junction temperature surveillance, and overpressure relief.
- High-fidelity endpoint detection: dual-wavelength colorimetric sensor tracks methyl red–bromocresol green indicator transition with 1.0 µL titrant resolution, eliminating subjectivity and drift-related errors.
- Robust corrosion-resistant construction: all wetted components—including digestion tube holders, distillation chamber, condenser jacket, and titration manifold—are fabricated from PTFE-coated stainless steel or high-purity borosilicate glass.
- Onboard data management: 16 GB internal eMMC storage retains ≥5 million test records; export formats include native .xlsx with embedded metadata (sample ID, operator, timestamp, method version, calibration log).
Sample Compatibility & Compliance
The HM-DN2 accommodates heterogeneous sample types common in regulated laboratories: ground cereals, dairy powders, feed pellets, soil extracts, wastewater digests, pharmaceutical excipients, and botanical matrices. Solid samples up to 8.0 g and liquid samples up to 30.0 mL are processed without manual intervention. Each analysis meets ISO 5983-1:2021 repeatability criteria (≤0.5% RSD for parallel digestions) and recovery validation per AOAC 992.15 (99–101%). Instrument qualification includes IQ/OQ documentation templates aligned with FDA 21 CFR Part 11 for electronic records and signatures, supporting audit readiness for food safety (FSMA), feed safety (FDA FSVP), and environmental compliance (EPA Method 350.1).
Software & Data Management
Data acquisition and reporting are governed by embedded firmware with configurable user roles (operator, supervisor, administrator). All actions—method edits, calibration events, maintenance logs, and result exports—are time-stamped and digitally signed. Excel reports contain full traceability: digestion batch ID, distillation cycle duration, titrant consumption (mL), calculated N %, protein conversion factor (e.g., 6.25, 5.70), and uncertainty estimation per GUM guidelines. USB mass storage enables direct report transfer; optional Wi-Fi module supports secure TLS 1.2 upload to LIMS or cloud-based QA platforms. Print output via built-in thermal printer complies with ISO/IEC 17025 record retention standards.
Applications
This system serves as a reference-grade tool across multiple sectors requiring regulatory-grade nitrogen determination: QC labs in dairy processing (casein, whey protein), animal feed mills (crude protein certification), agricultural extension services (soil fertility assessment), environmental testing (wastewater TN, sludge N), and academic research (plant nutrition studies, enzymatic hydrolysis kinetics). Its 3–9 min/sample throughput (dependent on matrix complexity and digestion protocol) enables batch processing of >60 samples per 8-hour shift—critical for contract testing labs operating under ISO/IEC 17025 accreditation.
FAQ
What digestion units are compatible with the HM-DN2?
The instrument interfaces with standard 100–500 mL Kjeldahl digestion tubes (e.g., Borosilicate Class A, ISO 17993-compliant); no proprietary consumables required.
Does the system support custom protein conversion factors?
Yes—users can define and save up to 20 matrix-specific factors (e.g., 5.70 for wheat gluten, 6.38 for milk) directly in method parameters.
How is calibration verified during routine operation?
Daily verification uses certified ammonium sulfate reference material (NIST SRM 2000 series); recovery must fall within 99–101% before sample analysis commences.
Is remote diagnostics supported?
Via optional Wi-Fi, technicians can initiate firmware updates, retrieve error logs, and perform sensor self-tests—subject to enterprise network security policies.
What maintenance intervals are recommended?
Peristaltic pump tubing replacement every 6 months; condenser cleaning every 200 runs; annual full-system performance verification per manufacturer’s PQ protocol.
