HORIBA LAQUAtwin pH B-711/B-712 Pocket-Sized pH Meter

Overview

The HORIBA LAQUAtwin pH B-711 and B-712 are compact, handheld pH meters engineered for rapid, reliable field and laboratory measurements using a flat-surface glass electrode architecture. Unlike conventional combination electrodes requiring bulk sample immersion, these instruments operate on the principle of direct-contact potentiometry: hydrogen ion activity in micro-volume samples generates a Nernstian potential across the integrated pH-sensitive glass membrane, which is converted into a calibrated pH reading via an internal high-impedance amplifier. Designed as successors to the B-211/B-212 series, the B-711/B-712 deliver enhanced electrode stability, reduced drift, and improved response time—enabling accurate measurement from as little as 0.05 mL of aqueous solution. Their application scope spans quality control in food processing, environmental water screening, aquaculture monitoring, educational labs, and point-of-use verification in pharmaceutical manufacturing where minimal sample consumption and instrument portability are critical.

Key Features

• Flat-surface glass electrode with optimized hydration layer kinetics for fast (<5 s), reproducible readings from microliter volumes
• IP67-rated enclosure ensures full protection against dust ingress and temporary submersion (1 m depth, 30 min), meeting IEC 60529 requirements for rugged field deployment
• Intuitive single-button operation: press once to initiate calibration or measurement; visual confirmation via smiley-face icon on LCD display
• Automatic temperature compensation (ATC) across 5–40 °C using built-in thermistor; compensation coefficient fixed at 2 %/°C per ISO 7888
• Auto-hold function freezes stable readings automatically, eliminating manual timing errors during batch testing
• Lightweight design (≈50 g body weight) with ergonomic pen-form factor and included protective carrying case for daily transport and storage

Sample Compatibility & Compliance

The B-711/B-712 are validated for use with clear, low-turbidity aqueous solutions including drinking water, nutrient solutions, buffer standards, and processed food extracts. For particulate-laden or viscous samples, HORIBA recommends pre-filtration using certified 0.45 µm membrane filters (sold separately) to prevent electrode clogging and surface fouling. The instruments comply with key international metrological guidelines: calibration traceability to NIST-traceable pH 4.01, 7.00, and 9.21 reference standards; measurement uncertainty aligned with ISO 11293 (routine pH measurement in water quality analysis); and electrical safety conforming to IEC 61010-1:2010 for portable measuring equipment. While not certified for GMP-regulated production environments, their audit-ready calibration logs (when used with optional PC interface software) support GLP-aligned documentation practices.

Software & Data Management

Although the B-711/B-712 operate as standalone instruments without onboard memory, they are compatible with HORIBA’s optional LAQUA Connect software (Windows/macOS) via USB-to-serial adapter. This enables export of timestamped calibration and measurement records—including electrode slope, offset, temperature, and user-defined sample IDs—to CSV or Excel formats. All data exports include embedded metadata required for basic 21 CFR Part 11 compliance: operator ID, device serial number, calibration date/time, and measurement sequence. Firmware updates are distributed through HORIBA’s secure customer portal and require no hardware modification.

Applications

• On-site verification of municipal and bottled water pH per EPA Method 150.1 and ISO 10523
• Routine monitoring of hydroponic and aquaponic nutrient reservoirs to maintain optimal plant root zone conditions
• Quick-check validation of cleaning-in-place (CIP) rinse water neutrality in food and beverage facilities
• Student experiments in general chemistry and environmental science curricula requiring low-cost, durable instrumentation
• Field-based assessment of soil extract pH (using 1:5 water suspension method per ASTM D4972)
• Pre-screening of cosmetic formulations and topical pharmaceuticals prior to full QC release testing

FAQ

What is the minimum sample volume required for accurate measurement?
0.05 mL when used with the optional LAQUAtwin Sampling Film (B-771 accessory); otherwise, ≥0.1 mL is recommended for consistent contact with the flat electrode surface.
Can the B-711 perform two-point calibration?
No—the B-711 supports only one-point calibration (typically at pH 7.00). For two-point calibration (e.g., pH 4.01 and pH 7.00), the B-712 model is required.
Is the instrument suitable for measuring pH in non-aqueous or high-alcohol solutions?
Not recommended. The flat glass electrode is optimized for aqueous electrolyte systems. Measurements in solvents with dielectric constant 20 % v/v) may yield unstable potentials and erroneous readings due to junction potential shifts.
How often should the electrode be cleaned and reconditioned?
Rinse with deionized water after each use. For routine maintenance, soak the sensing surface in 0.1 M HCl for 5 minutes weekly. Store immersed in pH 4 buffer or专用 storage solution (HORIBA B-700S) to preserve hydration layer integrity.
Does IP67 rating permit underwater operation?
No. IP67 certifies resistance to temporary immersion (1 m, 30 min), but active measurement must occur above liquid level. Submerged operation risks electrolyte dilution and irreversible electrode damage.