Leichi DDSJ-319L Benchtop Conductivity Meter

Overview

The Leichi DDSJ-319L is a high-precision benchtop conductivity meter engineered for rigorous laboratory applications in environmental monitoring, pharmaceutical water testing, chemical process control, and academic research. It operates on the principle of two-electrode or four-electrode conductometric measurement—applying an alternating current across a defined electrode cell and measuring the resulting conductance to determine solution conductivity. The instrument simultaneously calculates derived parameters—including resistivity, total dissolved solids (TDS), and salinity—using configurable algorithms aligned with internationally recognized standards such as ISO 7888 (water quality — determination of electrical conductivity), ASTM D1125 (standard test methods for electrical conductivity of water), and USP (Water Conductivity). Its wide dynamic range (0.000 µS/cm to 3000 mS/cm) accommodates ultrapure water analysis (e.g., Type I reagent water per ISO 3696/GB/T 6682) through highly concentrated brines and industrial electrolytes, all within a single, stable platform.

Key Features

• Intelligent endpoint detection: Supports auto-read, timed-read, interval-read, and manual-read modes to optimize workflow consistency and minimize operator dependency.
• Automatic temperature compensation (ATC): Utilizes integrated Pt1000 sensor with programmable compensation curves (linear, NaCl, or custom) to correct conductivity values to 25 °C reference, ensuring traceable comparability across samples.
• Multi-point calibration management: Recognizes up to five standard solutions; includes built-in recognition for four Chinese national standard (GB) conductivity standards (e.g., 1413 µS/cm, 12.88 mS/cm), enabling rapid, error-resistant calibration verification.
• Smart frequency switching: A single conductivity cell automatically adjusts excitation frequency (e.g., 30 Hz to 1 kHz) to maintain optimal signal-to-noise ratio across low- and high-conductivity ranges—eliminating manual cell swapping and reducing measurement drift.
• Comprehensive compensation models: Includes pure-water conductivity correction (per ISO 3696 Annex B), seawater salinity compensation (PSS-78 algorithm), and customizable TDS conversion factors (0.4–1.0) for accurate reporting in diverse matrices.
• Integrated automation interface: Equipped with RS-232 and USB-B ports to connect external automatic samplers or titrators, enabling unattended calibration sequences and batch sample processing with timestamped metadata.

Sample Compatibility & Compliance

The DDSJ-319L is validated for aqueous samples across pH 2–12 and viscosity ≤10 mPa·s. It accepts standard DIN/ISO-compatible conductivity cells (e.g., K=0.01, 0.1, 1.0, 10 cm⁻¹) and supports both two-electrode (for low-to-moderate conductivity) and four-electrode (for high-conductivity or polarizable samples) configurations. All measurement data are logged with full audit trail—including operator ID, calibration history, electrode serial number, ambient temperature, and timestamp—ensuring compliance with GLP (Good Laboratory Practice) and GMP (Good Manufacturing Practice) requirements. Data integrity meets FDA 21 CFR Part 11 criteria when used with password-protected user roles and electronic signature-enabled software export.

Software & Data Management

The instrument embeds a secure, role-based data management system supporting method templates, electrode lifecycle tracking (including usage count and recalibration alerts), and hierarchical user permissions (Admin, Technician, Viewer). Up to 1000 complete measurement records—including raw conductance, compensated values, and environmental metadata—are stored internally with non-volatile memory retention. Data export is supported via USB mass storage (to U-disk) or direct PC connection using Leichi’s proprietary PC Suite v3.2, which enables CSV/Excel export, statistical analysis (mean, SD, RSD, trend charts), and PDF report generation with embedded calibration certificates. All exported files retain embedded digital signatures and hash-verified integrity checks.

Applications

• Pharmaceutical water systems: Routine QC of Purified Water (PW) and Water for Injection (WFI) per USP and EP 2.2.38.
• Environmental labs: Monitoring conductivity in surface water, groundwater, wastewater effluent, and seawater per ISO 5667-3 and EPA Method 120.1.
• Power plant chemistry: Boiler feedwater and condensate purity assurance in accordance with ASTM D4582 and IAPWS guidelines.
• Academic research: Electrolyte characterization, membrane performance evaluation (e.g., EDI, RO reject streams), and ion exchange resin regeneration endpoint detection.
• Food & beverage QA: Salt concentration verification in brines, sauces, and dairy processing streams using salinity mode with PSS-78 compensation.

FAQ

What calibration standards are preloaded in the DDSJ-319L?
The meter includes factory-programmed recognition for four GB-standard conductivity solutions: 1413 µS/cm, 12.88 mS/cm, 111.8 mS/cm, and 1.413 S/cm. Users may add up to one custom standard.
Does the instrument support four-electrode conductivity measurement?
Yes—it accepts four-electrode cells for high-accuracy, polarization-free measurements in conductive or viscous media (e.g., seawater, acid baths, or slurries).
How is data integrity ensured for regulatory audits?
All measurements include immutable timestamps, operator login context, electrode ID, calibration status, and environmental conditions—fully compliant with GLP documentation requirements and suitable for 21 CFR Part 11 validation protocols.
Can the DDSJ-319L be integrated into LIMS or SCADA systems?
Via ASCII protocol over RS-232 or Modbus RTU over optional RS-485 adapter, enabling bidirectional communication with laboratory information management systems (LIMS) and industrial control platforms.
What is the temperature measurement accuracy specification?
±0.1 °C over the full operating range (−5.0 to 130.0 °C), verified per IEC 60751 for Pt1000 sensors, with resolution of 0.1 °C.