Zhuochi AOX-WK-S Microcoulometric Adsorbable Organic Halogens (AOX) Analyzer

Overview

The Zhuochi AOX-WK-S Microcoulometric Adsorbable Organic Halogens (AOX) Analyzer is a fully integrated, laboratory-grade instrument engineered for the precise quantification of adsorbable organic halogen compounds—including chlorinated, brominated, and iodinated organics—in aqueous environmental matrices. It operates on the principle of high-temperature catalytic combustion followed by microcoulometric titration, in strict accordance with China’s national standard HJ 1214–2021, as well as internationally recognized protocols including ISO 9562 and ASTM D5908. Water samples are first passed through activated carbon columns to adsorb halogenated organic compounds; the loaded carbon is then combusted at 950 °C under oxygen-rich conditions, converting all bound halogens into hydrogen halides (HX). These gaseous species are swept into an electrolytic titration cell where quantitative electrochemical detection occurs via silver ion generation and coulometric endpoint determination. This method delivers high specificity for total halogen content without interference from inorganic halides—provided proper sample pretreatment (e.g., acidification, filtration, and chloride removal) is performed.

Key Features

• Compliance-certified architecture: Fully aligned with HJ 1214–2021 mechanical, thermal, and signal-processing requirements—including dedicated combustion furnace design, quartz sample cup geometry, and dual-stage gas drying/adsorption configuration.
• Dual-function combustion system: Integrated programmable furnace with precision temperature control (±5 °C) and inert gas purging capability to minimize background halogen contamination.
• Microcoulometric detection module: Equipped with a dual-electrode titration cell (Ag/Ag₂S reference + Pt indicator), optimized for low-noise current measurement and sub-microgram-level halogen sensitivity.
• Modular hardware layout: Separated combustion, gas conditioning, and titration workstations mounted on rigid aluminum frames with standardized fittings (ground-glass joints, PTFE tubing, and stainless-steel gas lines) to ensure long-term seal integrity and reproducible flow dynamics.
• Robust sample handling suite: Includes custom-designed ceramic combustion boats, quartz sample cups, nitrogen-pressurized activation columns, and chlorine-free filter paper sets—all traceable and pre-cleaned to meet GLP-grade blank requirements.
• Integrated vacuum-assisted filtration station: Paired with a diaphragm vacuum pump and AOX-specific filter housing to support rapid, particle-free carbon loading without solvent carryover or column channeling.

Sample Compatibility & Compliance

The AOX-WK-S supports analysis of surface water, groundwater, wastewater effluents, drinking water, and industrial process streams. It accommodates sample volumes from 10 mL to 1 L, depending on expected AOX concentration and required detection limit. All wetted components—including quartzware, activated carbon (AOX-grade, 50 mL columns), and gas-drying tubes—are certified chlorine-free and validated for ≤0.5 µg Cl⁻ blank contribution per run. The system meets essential regulatory prerequisites for environmental laboratories operating under CNAS (China National Accreditation Service) and CMA (China Metrology Accreditation) frameworks. Its software supports 21 CFR Part 11-compliant user authentication, electronic signatures, and full audit trail logging—including method parameters, calibration history, raw coulombic integrals, and manual intervention records.

Software & Data Management

AOX-Control v3.2 is a Windows-native application designed for method-driven operation, real-time signal visualization, and automated report generation. It enables stepwise execution of HJ 1214–2021 workflows—including automatic blank subtraction, multi-point calibration curve fitting (linear or quadratic), spike recovery calculation, and uncertainty propagation per ISO/IEC 17025 guidelines. Data files are stored in encrypted SQLite format with SHA-256 hash integrity verification. Export options include CSV, PDF analytical reports (with embedded chromatogram-like titration curves), and XML for LIMS integration. All software updates are digitally signed and distributed via secure HTTPS portal—no third-party cloud dependencies.

Applications

• Regulatory monitoring of AOX discharge limits in municipal and industrial wastewater treatment plants (per GB 8978–1996 and local environmental protection bureau mandates).
• Process validation in pulp and paper mills, chlor-alkali facilities, and pharmaceutical manufacturing sites where halogenated solvents or disinfection by-products are used.
• Research on formation and fate of disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs) in chlorinated drinking water systems.
• Environmental impact assessments (EIAs) requiring baseline AOX profiling of receiving waters near chemical manufacturing zones.
• Method verification studies supporting inter-laboratory comparison programs coordinated by provincial EPBs or national institutes like CNEMC.

FAQ

What standards does the AOX-WK-S comply with?
It is fully compliant with HJ 1214–2021, and its operational methodology aligns with ISO 9562 and ASTM D5908 for adsorbable organic halogen determination.
Is the system suitable for unattended overnight operation?
Yes—the combustion furnace includes overtemperature cutoff, gas-flow monitoring, and auto-shutdown upon titration endpoint confirmation; however, operator supervision is recommended during initial method validation and high-throughput batches.
Can the instrument quantify individual halogens (Cl, Br, I) separately?
No. The AOX-WK-S measures total adsorbable organic halogens as chloride-equivalent mass; speciation requires complementary techniques such as GC-ECD or IC-MS.
What maintenance intervals are recommended for routine use?
Quartz components should be inspected after every 50 runs; electrolyte solution in the titration cell must be replaced weekly; activated carbon columns require regeneration or replacement after 10–15 sample loads, depending on matrix complexity.
Does the system support external LIMS connectivity?
Yes—via configurable ODBC drivers and XML-based data export modules compatible with major LIMS platforms including LabWare, STARLIMS, and Thermo Fisher SampleManager.