Shenchanghong CHTA-211 Total Alkalinity Analyzer

Overview

The Shenchanghong CHTA-211 Total Alkalinity Analyzer is a dedicated laboratory-grade photometric instrument engineered for the precise quantification of total alkalinity in aqueous samples—expressed as milligrams per liter of calcium carbonate (mg/L as CaCO₃). Total alkalinity represents the acid-neutralizing capacity of water, defined as the sum concentration of all proton-accepting species, primarily bicarbonate (HCO₃⁻), carbonate (CO₃²⁻), and hydroxide (OH⁻) ions. The CHTA-211 employs standardized colorimetric methodology based on acid titration with endpoint detection via optical absorbance measurement at a fixed wavelength. It implements a calibrated pH-sensitive indicator system (e.g., bromocresol green–methyl red mixed indicator) to generate a stable, measurable color change proportional to alkalinity concentration. Designed for routine compliance monitoring and method validation, the analyzer complies with core principles outlined in APHA Standard Methods 2320 B (Titrimetric Method) and ISO 9963-1:1994 (Water quality — Determination of alkalinity — Part 1: Titrimetric methods), while offering rapid, operator-independent photometric readout.

Key Features

• High-stability optical architecture featuring imported long-life (≥100,000 h), high-luminance LED light source coupled with precision narrow-band interference filters—minimizing spectral drift and ambient light interference.
• Integrated 16-bit low-power microcontroller system enabling robust signal processing, automatic zero calibration, and real-time temperature-compensated absorbance calculation.
• Backlit monochrome LCD display with full Chinese-language interface and hierarchical menu navigation—optimized for field-deployable lab technicians with minimal training requirements.
• Dual-curve storage capability: factory-preloaded calibration curve plus one user-definable curve, supporting method verification, matrix-matched standardization, and multi-lab traceability.
• Chemically resistant ABS polymer housing—engineered for durability in humid laboratory environments and resistance to common reagents including dilute HCl, buffer solutions, and indicator dyes.
• Low thermal load design (30 W max power draw) and compact footprint (266 × 200 × 130 mm) enable seamless integration into constrained benchtop workflows without auxiliary cooling or ventilation.

Sample Compatibility & Compliance

The CHTA-211 is validated for use with potable water, surface water, groundwater, wastewater effluents, and treated industrial process water. Sample turbidity must be < 5 NTU; suspended solids should be removed by filtration (0.45 µm membrane) prior to analysis to avoid scattering artifacts. The instrument supports manual sample introduction using standard 10–25 mL volumetric flasks and calibrated pipettes per APHA 2320 B protocol. Data output conforms to GLP documentation standards: each measurement record includes timestamp, operator ID (manually entered), sample ID, calibration status flag, and raw absorbance value. While not FDA 21 CFR Part 11–certified out-of-the-box, audit trails and calibration logs are exportable in CSV format for integration into LIMS or electronic lab notebook (ELN) systems meeting ISO/IEC 17025:2017 requirements.

Software & Data Management

The CHTA-211 operates autonomously without external PC dependency. All data—including up to 500 measurement records—are retained in non-volatile memory with battery-backed clock. Internal memory supports chronological recall, batch filtering by date range, and on-device statistical summary (mean, SD, CV%). Calibration curves are stored with metadata (date, standard lot number, analyst initials). Export is facilitated via RS-232 serial interface (DB9 connector) using ASCII-based protocol compatible with generic terminal emulators or custom Python/Excel VBA scripts. No proprietary software installation is required; firmware updates are performed via UART bootloader using standard FTDI adapters.

Applications

• Regulatory compliance testing for municipal drinking water utilities under GB/T 5750.4–2023 (China National Standard for Drinking Water Quality).
• Process control in lime-soda softening units and corrosion inhibition programs within industrial water treatment plants.
• Environmental monitoring of carbonate buffering capacity in freshwater ecosystems and estuarine transition zones.
• Educational laboratories conducting AP Chemistry or Environmental Engineering coursework on acid-base equilibria and water chemistry modeling.
• QA/QC verification of titration-based alkalinity results where rapid secondary confirmation is required without additional reagent consumption.

FAQ

What is the principle behind the CHTA-211’s alkalinity measurement?
It uses endpoint-detection photometry following standard acid titration with a dual-indicator system; absorbance shift at 610 nm correlates quantitatively with total titratable alkalinity.
Can the CHTA-211 measure phenolphthalein alkalinity separately?
No—it is configured exclusively for total alkalinity (methyl orange endpoint); phenolphthalein alkalinity requires manual titration or a dual-mode instrument.
Is calibration verification traceable to NIST standards?
Yes—users may calibrate using certified reference materials (CRMs) traceable to NIST SRM 3194 (Alkalinity Standard) or equivalent national metrology institute equivalents.
Does the instrument support automatic dilution?
No—samples exceeding 1000.0 mg/L must be manually diluted prior to analysis; dilution factor must be entered manually during result interpretation.
What maintenance is required for long-term optical stability?
Annual verification of LED output intensity and filter transmittance using manufacturer-provided check standards; no optical alignment or lamp replacement is needed within the 100,000-hour service life.