YSI 5000 / 5100 Benchtop Dissolved Oxygen Meter System (Galvanic Cell Type)

Overview

The YSI 5000 and 5100 benchtop dissolved oxygen (DO) meter systems are engineered for high-reproducibility, trace-level DO quantification in environmental, wastewater, and regulatory laboratory settings. These instruments operate on the galvanic electrochemical principle—utilizing a self-polarizing, oxygen-permeable membrane electrode that generates a current proportional to the partial pressure of molecular oxygen diffusing across the membrane. Unlike polarographic sensors requiring external polarization voltage, galvanic cells deliver immediate stabilization, eliminate warm-up delay, and ensure long-term baseline stability with negligible zero drift. The system is designed specifically for compliance-driven workflows, supporting standardized BOD₅ analysis per GB 7488–1987, HJ/T 99–2003, and US EPA Method 405.1. While the 5000 model provides foundational DO measurement and data logging, the 5100 extends functionality with embedded respirometry software for Oxygen Uptake Rate (OUR) and Specific Oxygen Uptake Rate (SOUR) calculations per USEPA Method 503—enabling activated sludge process control and biodegradability assessment without external computing.

Key Features

• Benchtop architecture with large backlit LCD display and tactile keypad interface—designed for ergonomic, glove-compatible operation in regulated lab environments
• Integrated motorized stirring in the YSI 5010 self-stirring DO probe (compatible with both 5000 and 5100)—ensures consistent hydrodynamic boundary layer control, eliminating manual stirring variability and improving inter-laboratory reproducibility
• Pre-tensioned 5906-type gas-permeable membrane assembly—factory-installed to eliminate installation-induced tension errors and reduce calibration frequency
• Real-time membrane integrity monitoring—automatically triggers visual and audible alerts when membrane permeability degrades or breaches occur
• Internal real-time clock with automatic timestamping for all stored readings (up to 100 records), supporting GLP-compliant audit trails
• Galvanic sensor design requires no zero adjustment—stable baseline performance verified at <0.002 mg/L drift over 24 hours
• Temperature compensation algorithm compliant with ISO 5814:2012—uses integrated thermistor (±0.1 °C accuracy) for automatic, non-linear DO correction across –5.0 to +50.0 °C

Sample Compatibility & Compliance

The YSI 5000/5100 platform is validated for aqueous matrices including raw and treated wastewater, surface water, groundwater, and BOD₅ dilution samples. It supports direct immersion of the 5010 probe (1.5 m cable, YSI 5011 connector) or static measurements using the non-stirring 5750 probe with external magnetic stirrer. All DO measurements adhere to ISO 5814:2012 (water quality—determination of dissolved oxygen—electrochemical probe method) and ASTM D888 (standard test methods for dissolved oxygen in water). For BOD₅ applications, the system satisfies Chinese national standards GB 7488–1987 and HJ/T 99–2003, and aligns with US EPA’s 40 CFR Part 136 requirements for wastewater discharge monitoring. The 5100’s built-in OUR/SOUR module implements USEPA Method 503 for activated sludge respirometry, including automatic temperature and barometric pressure compensation (integrated barometer eliminates external calibration dependency).

Software & Data Management

The YSI 5000/5100 supports dual-mode data handling: onboard storage (100 timestamped readings) and PC-based automation via YSI 5120 BOD Analysis Software. This Windows-installed application establishes bidirectional RS-232 communication, enabling full instrument control—including automated start/stop timing, stable-point detection (DO drift <0.02 mg/L/min for ≥60 s), and dynamic endpoint recognition. The software performs BOD₅ calculation per dilution factor, blank correction, seed correction, and load compensation—while generating audit-ready PDF reports compliant with 21 CFR Part 11 requirements (electronic signatures, operator ID, change history). Optional barcode scanner integration allows sample ID auto-entry, minimizing transcription errors. Firmware updates are field-deployable via keyboard interface—ensuring long-term regulatory adaptability without hardware replacement.

Applications

• Regulatory BOD₅ testing in municipal and industrial wastewater laboratories
• Activated sludge process optimization through OUR and SOUR profiling
• Environmental monitoring of rivers, lakes, and estuaries under national water quality standards
• Research-scale biodegradability screening (OECD 301 series, ISO 14851)
• Calibration verification and method validation studies requiring trace-level DO precision
• Teaching laboratories requiring robust, low-maintenance electrochemical instrumentation

FAQ

Does the YSI 5000/5100 require daily zero calibration?
No. The galvanic cell design exhibits negligible zero drift (<0.002 mg/L/24 h), and zero adjustment is neither necessary nor supported by the firmware.
Can the 5100 perform dissolved oxygen measurements without the 5010 self-stirring probe?
Yes—when used with the 5750 non-stirring probe, the instrument retains full DO measurement capability but requires external magnetic stirring to meet ISO 5814 hydrodynamic conditions.
Is barometric pressure compensation mandatory for accurate DO reporting?
Yes—partial pressure of oxygen is pressure-dependent. The 5100 includes an integrated barometer; the 5000 requires manual pressure entry or external sensor integration via optional analog input.
How does the system handle supersaturated samples (e.g., aerated effluent)?
The instrument detects saturation >100% and displays values up to 600%, applying Henry’s law-based correction while flagging potential sensor membrane saturation or electrolyte depletion.
What data security features support GLP/GMP compliance?
Timestamped storage, password-protected firmware updates, electronic audit trail generation (via 5120 software), and 21 CFR Part 11–compliant report export ensure traceability and data integrity for regulatory submissions.