Cycle-P Phosphate Sensor

Cycle-P Phosphate Sensor



High accuracy in-situ phosphate measurement

The Cycle P methodology is based on US EPA standard methods and combines precision fluidics with state-of-the-art optics to provide unparalleled precision and accuracy. Ideally suited for unattended monitoring the Cycle P includes pre-mixed onboard reagent cartridges and onboard calibration standards.


  • Robust: Excellent anti-fouling capability provided by copper mesh screens and 10 µm stainless steel intake filters
  • Accurate: Nanomolar resolution and scattering insensitive optical cell
  • Cost Effective: Over 1000 samples including onboard spike calibration for QA/QC, typical deployment duration of three months, reducing field costs


Height (w/handle) 56 cm
Width 18 cm
Weight in air 6.8 kg (w/ reagents)
Weight in water 0.37 kg
Depth 200 m
Temperature *1 1 … 35 °C
Input  10 … 18 VDC
Current draw 2.0 A max; 125 mA avg
Data output  RS-232 or SDI-12
Host Connector  MCBH-6-MP
SDI Connector MCBH-8-MP
Sample rate 2 per hour
Data memory 1 GB
LED wavelength 870 nm
Pathlength 5 cm
Linearity equal or greater than 95% R2
Detection limit, three standard deviations of 18 MOhm water equal to or less than 0.075 µM
equal to or less than 0.0023 mg/L PO4-P
Quantification limit, ten standard deviations of 18 MOhm water equal to or less than 0.25 µM
equal to or less than 0.0077 mg/L PO4-P
Standard deviation of standard solution of 2.6 µM equal to or less than 0.05 µM
equal to or less than 0.0015 mg/L PO4-P
Range, nominal *2 0 … 10 µM
0-0.3 mg/L PO4-P
Note: *1 Both storage and operating temperature for sensor and reagent cartridges.
*2 Higher range is possible (0 … 40 µM, 0 … 1.2 mg/L PO4-P) but is outside specifications
Units: M = moles per liter.
mg/L PO4-P refers to mg of atoms phosphorus per liter measured in the form of reactive phosphate.
ppm ~ mg/L, ppb ~µg/L

Specifications are subject to change without notice.