YSI DO200 Portable Dissolved Oxygen and Temperature Meter

Overview

The YSI DO200 Portable Dissolved Oxygen and Temperature Meter is a field-deployable, single-parameter instrument engineered for reliable, on-site measurement of dissolved oxygen (DO) concentration and water temperature in freshwater, estuarine, and coastal environments. It employs the well-established steady-state polarographic principle using a gas-permeable polyethylene (PE) membrane electrode, which ensures stable current output proportional to molecular oxygen diffusion rate across the membrane. Temperature is measured via a precision 10 kΩ thermistor calibrated per NIST-traceable standards. The integrated dual-sensor design eliminates inter-unit calibration drift between DO and temperature channels, supporting accurate automatic temperature compensation (ATC) without external referencing. Designed for routine environmental monitoring, wastewater process control, aquaculture management, and ecological field studies, the DO200 delivers traceable data under variable ambient conditions while maintaining compliance with fundamental quality assurance requirements for field instrumentation.

Key Features

• IP65-rated housing for dust-tight operation and protection against low-pressure water jets — suitable for rain-exposed field use and splash-prone sampling locations
• Stainless steel DO sensor with overmolded polymer protective sleeve, enhancing mechanical durability during repeated immersion and minimizing fouling risk
• Strain-relieved cable connector design reduces cyclic fatigue at the probe–cable junction, extending service life in high-mobility deployment scenarios
• Two standard cable lengths available (4 m and 10 m), enabling flexible vertical profiling or shore-based surface sampling without auxiliary reels or tripods
• Next-generation PE membrane with reduced stirring sensitivity and sub-30-second response time (t₉₀) in static water, improving measurement repeatability in low-flow or stagnant conditions
• Onboard automatic temperature compensation with user-accessible manual inputs for salinity (0–70 ppt) and barometric pressure (60–110 kPa), supporting DO correction per Winkler-derived solubility models
• Low-battery indicator and intuitive button-driven interface optimized for one-handed operation with gloved hands or wet conditions

Sample Compatibility & Compliance

The DO200 is validated for direct immersion in natural waters, treated effluents, aquaculture tanks, and laboratory mesocosms. Its polarographic sensor demonstrates minimal interference from common ions (e.g., Cl⁻, NO₃⁻, SO₄²⁻) and negligible cross-sensitivity to hydrogen sulfide below 0.5 mg/L. While not certified to ISO/IEC 17025 for accredited testing, the instrument supports GLP-aligned documentation practices through standardized field log templates and traceable calibration records. Sensor performance meets the functional criteria outlined in ASTM D888–22 (Standard Test Methods for Dissolved Oxygen in Water) for field portable systems, and its temperature accuracy conforms to ASTM E74–23 requirements for liquid-in-glass and electronic thermometers used in environmental applications.

Software & Data Management

The DO200 operates as a standalone field meter with no embedded memory or Bluetooth connectivity. All measurements are displayed in real time on a backlit LCD screen with dual-unit readout (mg/L and % air saturation). Users manually record values in field notebooks or digital logs compatible with LIMS platforms. Calibration verification follows a two-point DO procedure (zero-oxygen and saturated-air standards) per manufacturer guidelines, with documented date, operator ID, and environmental parameters (salinity, barometric pressure) retained for audit purposes. Though lacking FDA 21 CFR Part 11-compliant electronic signatures or audit trails, the device supports paper-based QA/QC workflows aligned with EPA Method 360.1 and ISO 5814:2012 for field DO determination.

Applications

• Routine stream and lake health assessments conducted by municipal environmental agencies and watershed associations
• Wastewater treatment plant influent/effluent monitoring for aeration basin optimization and regulatory reporting
• Aquaculture site management, including pond DO trending, feed timing support, and hypoxia early warning
• Academic and NGO-led biodiversity surveys requiring rapid, repeatable spot measurements across multiple transects
• Stormwater outfall screening prior to discharge authorization under NPDES permit conditions
• Calibration verification and field validation of fixed online DO sensors in distributed monitoring networks

FAQ

Does the DO200 support data logging or USB export?
No — the DO200 is a real-time display-only instrument with no internal memory or digital interface.
What calibration standards are required for routine use?
A zero-oxygen solution (sodium sulfite or nitrogen-purged distilled water) and an air-saturated water standard prepared at known temperature, salinity, and barometric pressure.
Is the probe suitable for long-term deployment?
No — the DO200 is designed for grab sampling and short-duration profiling; continuous immersion exceeds recommended operational limits for the PE membrane.
Can the instrument measure DO in seawater?
Yes — provided salinity is manually entered during setup to enable appropriate oxygen solubility correction.
How often should the PE membrane be replaced?
YSI recommends replacement every 2–4 weeks under regular field use, or immediately after exposure to oil, grease, or heavy biofouling.