Leici PXSJ-270F Fluoride Ion Meter

Overview

The Leici PXSJ-270F Fluoride Ion Meter is a precision benchtop potentiometric analyzer engineered for reliable, trace-level quantification of fluoride ions (F⁻) in aqueous samples. Based on the Nernstian response of a solid-state lanthanum fluoride (LaF₃) crystal membrane electrode, the instrument measures the potential difference between the ion-selective electrode (ISE) and a stable reference electrode (typically Ag/AgCl), converting it into concentration values via logarithmic calibration. Designed specifically for environmental water quality laboratories, municipal drinking water facilities, and industrial effluent monitoring stations, the PXSJ-270F delivers high reproducibility and long-term electrode stability under routine operational conditions. Its architecture conforms to fundamental electrochemical measurement principles defined in ISO 10523 (water quality — determination of pH) and supports method development aligned with EPA Method 300.0 and ASTM D6919 for anion analysis.

Key Features

• Benchtop form factor with integrated LCD display (128 × 64 pixels) and intuitive soft-key navigation for multi-parameter operation
• Dual-channel capability: simultaneous measurement of fluoride ion concentration and sample temperature with automatic temperature compensation (ATC)
• Advanced electrode diagnostics: real-time slope monitoring, asymmetry potential check, and electrode status indicator to ensure measurement integrity
• Calibration flexibility: supports 2–5 point calibration using standard fluoride solutions; built-in calibration curve verification and residual error reporting
• Robust input circuitry with ≥3 × 10¹² Ω input impedance to minimize loading effects and maintain signal fidelity during low-conductivity measurements
• Non-volatile memory stores up to 200 data sets with timestamp, electrode ID, calibration history, and user-defined sample IDs
• RS-232 interface compliant with standard serial protocols for direct connection to LIMS or PC-based data acquisition software

Sample Compatibility & Compliance

The PXSJ-270F is optimized for use with natural waters (surface, groundwater, drinking water), wastewater effluents, and industrial process streams containing fluoride at environmentally relevant concentrations (sub-ppb to ppm levels). Sample matrix compatibility includes TISAB (Total Ionic Strength Adjustment Buffer)-adjusted solutions per standard fluoride ISE methodology. The instrument meets general electrical safety requirements per GB/T 18268.1–2010 (equivalent to IEC 61326-1) and electromagnetic compatibility (EMC) criteria for laboratory environments. While not certified to FDA 21 CFR Part 11 out-of-the-box, its data logging structure—including immutable timestamps, operator ID fields, and calibration audit trails—supports GLP-compliant documentation when deployed within validated laboratory workflows.

Software & Data Management

Data export is performed via ASCII-formatted text files through the RS-232 port, enabling seamless import into Excel, LabArchives, or custom LIMS platforms. Each stored record includes measured [F⁻], mV potential, temperature, date/time stamp, calibration slope (%Nernst), and electrode identification. The meter does not include proprietary PC software; however, its communication protocol is publicly documented and compatible with third-party terminal emulators (e.g., Tera Term, PuTTY) for automated scripting and batch reporting. Audit-ready functionality includes manual entry of analyst ID and sample notes prior to storage—critical for QA/QC traceability in regulated environmental testing labs.

Applications

• Regulatory compliance monitoring of fluoride in public drinking water supplies per WHO guidelines (1.5 mg/L max) and US EPA MCL (4.0 mg/L)
• Process control in aluminum smelting and phosphate fertilizer manufacturing where fluoride emissions require continuous tracking
• Groundwater contamination assessment near fluorite mining or ceramic glaze production sites
• Educational laboratory instruction in analytical chemistry, focusing on ISE theory, calibration strategies, and activity vs. concentration corrections
• Verification of fluoride removal efficiency in activated alumina or bone char filtration systems

FAQ

Does the PXSJ-270F support calibration with non-fluoride standards or other ion-selective electrodes?
No. The PXSJ-270F is factory-configured exclusively for fluoride ion measurement and lacks configurable ion selection menus or generic ISE mode. It is not compatible with chloride, nitrate, or calcium ISEs.
Is a dedicated fluoride ISE included with the instrument?
Yes — the system ships with a LaF₃-based fluoride-selective electrode and a double-junction Ag/AgCl reference electrode, both pre-characterized and ready for immediate calibration.
Can the meter perform automatic drift correction during extended measurements?
No. Drift compensation is not implemented algorithmically; users must monitor electrode stability manually via periodic re-measurement of calibration standards or blank solutions.
What is the recommended maintenance interval for the fluoride electrode?
Electrode polishing with 0.5 µm alumina slurry is advised every 50–100 measurements or when slope falls below 92% of theoretical Nernst response (−59.2 mV/decade at 25 °C).
Is TISAB addition mandatory for all sample types?
Yes — TISAB (typically containing NaCl, acetic acid/acetate buffer, and CDTA) is required to control ionic strength, pH, and complexing interferences (e.g., Al³⁺, Fe³⁺) that suppress free fluoride activity.