Leici DDSJ-307F Benchtop Conductivity Meter

Overview

The Leici DDSJ-307F Benchtop Conductivity Meter is a precision-engineered electrochemical analyzer designed for routine and regulatory-compliant conductivity, resistivity, total dissolved solids (TDS), salinity, and temperature measurements in academic, industrial, and quality control laboratories. It operates on the principle of two-electrode or four-electrode conductometric measurement—applying an alternating current across a defined electrode geometry and calculating solution conductivity based on Ohm’s law and geometric cell constant correction. The instrument employs frequency-sweeping excitation to minimize polarization effects and electrode fouling, enabling stable readings across wide dynamic ranges—from ultrapure water (≥18.2 MΩ·cm) to highly concentrated brines (up to 1000 mS/cm). Its dual-temperature sensor architecture ensures accurate thermal compensation under variable ambient conditions, and its adherence to fundamental metrological traceability principles aligns with international standards including ISO/IEC 17025, ASTM D1125 (Standard Test Methods for Electrical Conductivity and Resistivity of Water), and ISO 7888 (Water Quality — Determination of Electrical Conductivity).

Key Features

• High-resolution graphical LCD display with dual-unit temperature readout (°C/°F) and user-selectable reference temperatures (20 °C or 25 °C)
• Intelligent endpoint detection with multiple reading modes: auto-read, timed-read, interval-read, and manual-hold
• Automatic temperature compensation (ATC) with configurable algorithms: non-compensated, linear (α = 2.0%/°C default), and pure-water mode (non-linear compensation per ISO 7888 Annex B)
• Auto-ranging electronics with adaptive resolution switching: 0.001 µS/cm minimum at low-conductivity ranges; 0.01 mg/L for TDS; 0.01% for salinity
• Integrated diagnostics: power-on self-test, battery-free memory retention, automatic shutdown, factory reset, and firmware upgradability via USB
• IP54-rated enclosure for dust resistance and limited water splashing protection—suitable for standard laboratory benchtop use
• Support for three electrode geometries (cell constants: 0.01, 0.1, 1.0 cm⁻¹) with automatic frequency selection to optimize signal-to-noise ratio across full measurement span

Sample Compatibility & Compliance

The DDSJ-307F accommodates aqueous samples ranging from deionized water and pharmaceutical buffers to seawater analogs and industrial process streams. Its extended resistivity range (5.00 Ω·cm to 20.00 MΩ·cm) enables characterization of high-purity water systems used in semiconductor rinsing or biopharmaceutical formulation. Calibration follows nationally recognized GB/T 6682 and GB/T 11025 protocols, with automatic recognition of four standardized KCl solutions (1413 µS/cm, 12.88 mS/cm, 111.8 mS/cm, and 1.413 S/cm). All measurement data are timestamped, operator-ID tagged (where enabled), and stored with full audit trail metadata—including calibration history, electrode ID, temperature, and compensation method—fully satisfying GLP documentation requirements and facilitating FDA 21 CFR Part 11 readiness when paired with validated PC software.

Software & Data Management

Data handling is governed by a robust internal memory system supporting up to 500 datasets per parameter group (conductivity, TDS, resistivity, salinity, temperature). Each record includes raw signal, compensated value, temperature, date/time stamp, and calibration status flag. Export is enabled via two physical interfaces: an RS-232 port compatible with industry-standard serial printers (user-configurable print templates), and a USB interface for bidirectional communication with Leici’s certified PC application. This software provides secure data export (CSV, TXT), report generation (PDF), calibration certificate printing, and optional electronic signature integration for regulated environments. All exported files retain embedded metadata required for ISO/IEC 17025 technical records and internal QA audits.

Applications

• Pharmaceutical water system validation (PW, WFI, Purified Water per USP )
• Environmental monitoring of surface water, groundwater, and wastewater effluents
• Food & beverage quality assurance (e.g., brine concentration, syrup density estimation)
• Electroplating bath composition control and rinse water purity verification
• Academic teaching labs for fundamental electrochemistry and solution thermodynamics experiments
• Chemical manufacturing QC for electrolyte strength assessment and catalyst wash efficiency

FAQ

What calibration standards does the DDSJ-307F support?
It automatically identifies four Chinese national standard KCl solutions (GB/T 11025): 1413 µS/cm, 12.88 mS/cm, 111.8 mS/cm, and 1.413 S/cm. Up to three-point calibration is supported with manual entry of non-standard solutions.
Can the instrument measure ultrapure water accurately?
Yes—when equipped with a 0.01 cm⁻¹ cell and operated in pure-water compensation mode, it achieves reliable resistivity readings up to 20.00 MΩ·cm with minimized capacitive coupling error.
Is the device compliant with FDA 21 CFR Part 11?
The hardware supports ALCOA+ data integrity principles; full Part 11 compliance requires implementation of validated third-party software with electronic signatures, audit trails, and role-based access controls.
Does it support electrode diagnostics or aging detection?
While no real-time electrode health algorithm is embedded, the instrument logs cell constant deviation during calibration and flags out-of-specification drift beyond ±5%—a key indicator of contamination or coating.
What is the operating temperature limit for continuous measurement?
The sensor input circuitry is rated for continuous operation between −5.0 °C and 110.0 °C; however, prolonged exposure above 80 °C may affect long-term stability of the integrated temperature sensor and should be verified per application-specific validation protocols.