Refined oil sensor

What is Refined Oil?

Refined oils are products derived from crude oil. BETX hydrocarbons are some examples, such as benzene, toluene, ethylbenzene, and xylenes. These hydrocarbons can be measured by the refined oils sensor.

Aquaread Refined Oil Sensor

The sensor is fixed response fluorometer, which provides excitation at 285nm (deep UV) and detects any resultant fluorescence between 330nm and 370nm.

The electrode induces the aromatic hydrocarbons within the refined oil to fluoresce, then measures the longer wavelength light which is emitted as a result of the fluorescence process.


Key Features

  • Dense sapphire lenses are used on our refined oil sensor for their high clarity and scratch resistance.
  • Specialised deep UV LED is used to excite the refined oil.
  • Measurement range 0 – 10,000µg/l.
  • Resolution: 0.1µg/l.
  • Repeatability: +/- 10% of reading.
  • Simple to install on a wide range of Aquaprobes.
  • Easy 2-point calibration using naphthalene salt.
  • Site specific calibration with grab sample calibration option.

Our Refined Oils sensors can be installed into many of our probes, below are some examples.

To see all of the probes can house the refined oils sensor please visit the Products section



Single parameter Aquaprobe, for use with any of our sensors.



The Aquasonde-5000 has 4 spare ports. They can house any combination of ISE and Optical sensors.



Advanced portable multi-parameter Aquaprobe.

Simple installation

Installing the refined oil sensor into an Aquaprobe is a very simple process. Simply unscrew the blanking plug from an appropriate aux socket, apply some silicon grease to the thread of the sensor (grease provided) and screw in the sensor. After installation full calibration is required.


In order to 'calibrate' the REFOIL electrode, a 10ppm calibration solution of 1-5, naphthalenedisulfonic acid disodium salt should be used. This solution contains naphthalene, an aromatic hydrocarbon, which has similar fluorescence characteristics to many Refined Oils.

The 10ppm calibration solution should be freshly prepared by serial dilution from pure 1-5, naphthalenedisulfonic acid disodium salt. When calibrating the Refined Oil sensor with naphthalenedisulfonic acid disodium salt, the readings given will be in μg/L (ppb) naphthalene.

In order to display readings with respect to a specific type of refined oil, it is necessary to prepare a 10ppm solution of the target oil type and use that to calibrate the electrode in place of the naphthalene solution. Alternatively, apply a suitable Grab Sample Factor to correct the naphthalene readings for the target oil type.

Auto zero feature

When this sensor is deployed in an Aquaprobe or Aquasonde it is able to automatically calibrate the 0 point. It is able to do this by measuring the response when the deep UV LED is not active.