YSI 556MPS Multiparameter Water Quality Meter
| Brand | YSI |
|---|---|
| Origin | USA |
| Model | YSI 556MPS |
| Instrument Type | Portable Multiparameter Water Quality Analyzer |
| DO (Air Saturation) | 0–500%, Resolution: 0.1%, Accuracy: ±2% or ±2% air saturation (0–200%), ±6% (200–500%) |
| DO (mg/L) | 0–50 mg/L, Resolution: 0.01 mg/L, Accuracy: ±2% or ±0.2 mg/L (0–20 mg/L), ±6% (20–50 mg/L) |
| Temperature | −5 to +45 °C, Resolution: 0.1 °C, Accuracy: ±0.15 °C |
| Conductivity | 0–200 mS/cm, Resolution: 0.001–0.1 mS/cm (range-dependent), Accuracy: ±0.5% or ±0.001 mS/cm (4-m cable), ±1.0% or ±0.001 mS/cm (20-m cable) |
| Salinity | 0–70 ppt, Resolution: 0.01 ppt, Accuracy: ±1.0% or ±0.1 ppt |
| pH (optional) | 0–14, Resolution: 0.01, Accuracy: ±0.2 |
| ORP (optional) | −999 to +999 mV, Resolution: 0.1 mV, Accuracy: ±20 mV |
| TDS | 0–100 g/L, Resolution: 4-digit |
| Barometer (optional) | 500–800 mmHg, Resolution: 0.1 mmHg, Accuracy: ±3 mmHg (within ±15 °C of calibration temperature) |
Overview
The YSI 556MPS Multiparameter Water Quality Meter is a field-deployable, handheld instrument engineered for high-precision, real-time measurement of critical aquatic parameters in freshwater, estuarine, and marine environments. Built upon YSI’s legacy of electrochemical and thermistor-based sensor architecture, the 556MPS integrates six core sensors—temperature, conductivity, salinity, dissolved oxygen (DO), pH, and oxidation-reduction potential (ORP)—into a single, synchronized acquisition platform. Its measurement methodology relies on Clark-type polarographic DO sensing with fast-response, low-stirring-dependence polymer electrolyte (PE) membranes; potentiometric pH and ORP detection using glass and noble-metal reference electrodes; and four-electrode conductivity cells calibrated per ASTM D1125 and ISO 7888 standards. Designed for regulatory-grade field use, the system delivers traceable, reproducible data under dynamic environmental conditions—supporting compliance with EPA Method 160.1, APHA Standard Methods 4500-O, and ISO 5814 for dissolved oxygen.
Key Features
- Simultaneous real-time acquisition of up to seven parameters—including temperature, conductivity, salinity, DO (mg/L and % saturation), pH, ORP, and TDS—with all values displayed concurrently on a backlit, menu-driven LCD screen
- IP67-rated housing ensures full dust ingress protection and water immersion resistance up to 1 meter for 30 minutes; buoyant design enables automatic surface recovery if dropped into water
- Ergonomic, smartphone-style keypad allows intuitive one-handed operation, with integrated battery-level indicator and low-power sleep mode
- 512 KB internal memory stores up to 49,000 timestamped data records (date/time stamped) and 100 site-specific location IDs—enabling long-term unattended profiling or scheduled interval logging
- Modular probe architecture permits user-replaceable sensors in the field without tools or recalibration downtime; all probes feature ruggedized stainless-steel housings and NIST-traceable calibration certificates
- Supports optional barometric pressure compensation (500–800 mmHg range) and flow-through cell integration for continuous monitoring applications
Sample Compatibility & Compliance
The YSI 556MPS is validated for direct immersion in natural waters—including rivers, lakes, wetlands, coastal zones, wastewater effluents, and aquaculture systems. Its sensor suite meets the operational requirements of U.S. EPA Region 10 Field Manual protocols and aligns with ISO/IEC 17025:2017 principles for field measurement uncertainty estimation. Conductivity and salinity measurements adhere to ASTM D1125 (Standard Test Method for Electrical Conductivity of Water) and are cross-validated against KCl standard solutions at 25 °C. DO accuracy specifications conform to ISO 5814:2012 (Water quality — Determination of dissolved oxygen — Electrochemical probe method). The instrument supports GLP-compliant data integrity through EcoWatch™ software audit trails and time-stamped metadata embedding.
Software & Data Management
Data transfer occurs via USB connection to Windows-based PCs running YSI EcoWatch™ software—a validated application compliant with FDA 21 CFR Part 11 for electronic records and signatures. EcoWatch™ provides automated calibration verification logs, statistical summaries (mean, SD, min/max), customizable report templates (PDF/CSV/XLSX), and geotagged site mapping. All stored datasets include embedded timestamps, operator ID fields, and sensor-specific calibration history. Software-generated reports support audit readiness for state water quality agencies (e.g., TCEQ, NYDEC) and third-party environmental laboratories accredited to ISO/IEC 17025.
Applications
- Regulatory ambient water quality monitoring per Clean Water Act Section 305(b) reporting requirements
- Wastewater treatment plant influent/effluent characterization and process control
- Aquatic ecosystem health assessments—including hypoxia event detection and eutrophication trend analysis
- Marine and estuarine salinity stratification studies supporting NOAA NOS hydrographic survey protocols
- Academic and research field campaigns requiring multi-parameter synchronicity and ruggedized portability
- Stormwater runoff evaluation and Total Maximum Daily Load (TMDL) implementation support
FAQ
Can the YSI 556MPS be used for continuous unattended monitoring?
Yes—when paired with optional accessories such as the Flow-Through Cell and external power supply, the 556MPS supports scheduled logging intervals from 1 second to 24 hours, with data retained in non-volatile memory.
Is pH calibration required before each deployment?
While two-point (pH 4.01 and 7.00 or 10.01) calibration is recommended prior to critical measurements, the system retains calibration coefficients across power cycles and supports slope/offset validation checks between field sessions.
How does the instrument compensate for temperature effects on conductivity readings?
The 556MPS applies automatic temperature compensation (ATC) using a built-in thermistor, with linear or nonlinear (NaCl-based) algorithms selectable per ASTM D1125 Annex A1.
Are sensor calibrations traceable to national standards?
All factory calibrations are performed against NIST-traceable reference standards, and calibration certificates include uncertainty budgets calculated per GUM (Guide to the Expression of Uncertainty in Measurement).
Does the system support export to LIMS platforms?
Yes—EcoWatch™ exports fully structured CSV files compatible with major LIMS vendors including LabWare, Thermo Fisher SampleManager, and Waters Empower, with configurable column headers and metadata tagging.
