Leici DDSJ-307F Benchtop Conductivity Meter

Overview

The Leici DDSJ-307F is a high-precision benchtop conductivity meter engineered for routine and regulatory-compliant measurements in quality control laboratories, environmental testing facilities, and academic research settings. It operates on the principle of two-electrode AC conductivity measurement—applying a low-frequency alternating current across a conductive cell to determine solution conductance while minimizing polarization effects. The instrument simultaneously computes and displays conductivity, resistivity, total dissolved solids (TDS), salinity, and temperature, with automatic temperature compensation (ATC) based on user-selectable reference temperatures (20 °C or 25 °C). Its wide dynamic range—from ultra-pure water (5.00 Ω·cm) to highly concentrated brines (1000 mS/cm)—is achieved through intelligent auto-ranging circuitry and adaptive electrode constant recognition, ensuring metrological integrity across diverse sample matrices without manual range switching.

Key Features

• High-resolution 4.3-inch TFT LCD display with adjustable backlight for clear visualization under varied lighting conditions
• IP54-rated enclosure providing protection against dust ingress and water splashes—suitable for standard laboratory environments with moderate humidity and incidental spill exposure
• Intelligent endpoint detection algorithms enabling stable automatic reading, timed acquisition (1–999 s intervals), and manual hold modes
• Multi-mode temperature compensation: non-compensated, linear (with α = 2.0%/°C default), and pure-water-specific compensation per ISO 7888 Annex B
• Auto-recognition of four standard GB/T 6682–2008 conductivity reference solutions (e.g., 1413 µS/cm, 12.88 mS/cm), supporting 1–3 point calibration with traceable documentation
• Frequency auto-switching function—optimized for use with K = 1.0 cm⁻¹ electrodes across full range; recommends K = 0.1 or 0.01 cm⁻¹ cells for sub-20 µS/cm samples to improve signal-to-noise ratio
• Integrated power management: auto-shutdown after 10 min idle, battery-free operation via universal AC/DC adapter (input 100–240 VAC, output 9 VDC)

Sample Compatibility & Compliance

The DDSJ-307F accommodates aqueous samples ranging from deionized water and pharmaceutical buffers to industrial process streams and seawater dilutions. Its calibrated measurement domain adheres to internationally recognized electrochemical standards—including ASTM D1125 (Standard Test Methods for Electrical Conductivity of Water) and ISO 7888 (Water quality — Determination of electrical conductivity)—supporting method validation under GLP and GMP frameworks. All stored data include mandatory metadata: date/time stamp, operator ID (user-definable), electrode serial number, calibration history, and ambient temperature. The device meets IEC 61010-1 safety requirements for laboratory electrical equipment and carries CE marking for conformity with EU electromagnetic compatibility (EMC) directives.

Software & Data Management

Data integrity is enforced through GLP-compliant audit trails: each measurement record contains immutable timestamps, calibration verification logs, and system diagnostic flags (e.g., electrode impedance check at startup). Up to 500 datasets per parameter type (conductivity, TDS, resistivity, salinity, temperature) are retained in non-volatile memory. Export is supported via dual interfaces: RS-232 (compatible with ESC/P and PCL printers for direct hardcopy reports with configurable layout) and USB-B (enabling bidirectional communication with Leici’s proprietary PC software for CSV export, trend analysis, and electronic signature-enabled report generation). Firmware updates are performed locally via USB drive, preserving configuration files and calibration coefficients during version upgrades.

Applications

• Pharmaceutical water systems monitoring (PW, WFI) per USP and EP 2.2.38
• Environmental water quality assessment (surface water, groundwater, wastewater effluent)
• Chemical manufacturing process control—electrolyte concentration verification in plating baths, etchants, and cleaning solutions
• Food & beverage QC—salt content estimation in brines, dairy products, and sauces
• Academic teaching labs—demonstration of ion mobility, Kohlrausch’s law, and temperature dependence of electrolytic conduction
• Power plant boiler feedwater purity assurance (resistivity > 10 MΩ·cm threshold verification)

FAQ

What electrode constants are supported?
The DDSJ-307F natively supports K = 0.01, 0.1, and 1.0 cm⁻¹ electrodes. Automatic cell constant input is enabled during calibration; manual entry is also available.
Does the instrument support FDA 21 CFR Part 11 compliance?
While the DDSJ-307F itself does not provide electronic signatures or role-based access control, its data export protocols and audit-trail structure align with Part 11 foundational requirements when integrated into validated LIMS or ELN workflows.
Can it measure conductivity in organic solvents?
No—it is designed exclusively for aqueous electrolyte solutions. Non-aqueous media require specialized impedance analyzers due to dielectric and polarization limitations.
Is calibration traceability documented?
Yes. Each calibration event generates a timestamped log including standard solution lot numbers, measured values, deviation from certified values, and pass/fail status per ±1.0% FS tolerance.
What is the operating temperature limit for the included composite electrode?
The standard K = 1.0 electrode is rated for continuous use from 0 °C to 60 °C; intermittent exposure up to 80 °C is permissible with reduced lifespan.