• Drinking water
  • Process optimisation of wastewater treatment plants
  • Industrial and municipal wastewater
  • Mineral water monitoring
  • Surface water


The instrument is ideal for potable water or suface water analysis and with the addition of a dilution module is also capable of the determination of nitrates in complex matrices such as urban and industrial wastewaters.
The determination ranges of the nitrate analyzer vary from trace μg/L to 25.0 mg/L N-NO3 (80 mg/L NO3) using the (optional) internal dilution module. The result can be expressed as NO3 or N-NO3.


Both hydrazine and copper catalyst reagents are used to reduce Nitrate to Nitrite in a basic medium inside a heated reaction cell. A sulfanilamide and N-(1-naphthyl)-ethylene diammonium dichloride reagent is added to react with the Nitrite to form a purple colored compound. The absorbance intensity is proportional to the Nitrite concentration in the sample and is measured at 525 nm


Measured parameter NO3-


(Ø 26 mm) 2 - 400 ppb N-NO3 (1.28 ppm NO3)
(Ø 16 mm) 4 - 650 ppb N-NO3 (2.08 ppm NO3)
(with dilution) 25 ppm N-NO3 (80 ppm NO3)


* if two values take whichever is greater.
(Ø 26 mm) ± 2 ppb / ± 5%
(Ø 16 mm) ± 5 ppb / ± 5%
Limit of detection 2 ppb
Wavelength 525 nm
Demineralized water Not required
Termoregulation 37 °C
Number of reagents 3
Min. analysis time 11 minutes
Default analysis time 20 minutes

Reagent consumption**

** per month, at the default analysis frequency.
(Ø 26 mm) 5.8 L
(Ø 16 mm) 4.3 L

Technical Specifications

Model 3S-CL
Sampling Mode Batch, with freely settable frequency.
Sample Pressure: Atmospheric
Temperature: 5 ‐ 45°C (41 ‐ 113°F)
Flow Rate: 80 to 500 mL/min
Connection: 6 mm (¼-in.)
Drain Pressure-free drain
Connection: 12 mm (½-in.)
Input Streams 2
Material Epoxy-coated stainless steel AISI 304
Dimensions (H x W x D) 604 x 380 x 210 mm (23.6 x 14.8 x 8.2 in)
Weight 20 kg (44 lbs)
Power Supply Input Voltage: 115 VAC,230 VAC,24 VDC
Power consumption: max. 80 W
Output signals 2 x 4-20 mA analog outputs
Modbus via RS485,Ethernet
Alarms 2 SPDT programmable voltage-free relays
Digital Input None, Online, Start Extra, Skip Idle, Emergency Stop
Ambient Temperature 5 - 45 °C (41 - 113 °F)
Ambient Humidity 10 - 90 % RH (non-condensing)
Protection Grade IP54 (indoor only, outdoor use possible with external cabinet, not included)