AdBlue®/DEF: Refractometric Analysis

AdBlue®, also known as DEF, is an aqueous urea solution. It lowers nitrogen oxides in diesel emissions. International standards demand that refractive index be measured for the determination of the urea concentration in AdBlue®.

AdBlue® goes green

AdBlue® is an aqueous solution with a concentration of 32.5 % urea. In North America, it is referred to as DEF (for "diesel exhaust fluid"). Urea reacts with nitrogen oxides and creates environmentally safe nitrogen and water. AdBlue® is therefore added to diesel to lower nitrogen oxide emissions. In countries where taxes are graduated according to vehicle emissions, reduced emissions of nitrous oxides may be cost efficient. Moreover, the addition of AdBlue® results in a reduction of fuel consumption by 3 % to 8 %.

The international standard ISO 22241 demands the analysis of AdBlue® using one of several defined methods. ISO 22241-2 Annex C specifies the determination of urea content in AdBlue® with refractive index measurement.

Anton Paar’s refractometers of the Performance Plus and Heavy Duty lines are ideal for measuring refractive index in AdBlue®

Compared to other methods, refractive index measurements are highly cost effective, fast and do not require highly trained operators. ISO 22241-2 Annex C requires the use of refractometers

  • Refractive index range from 1.33000 to 1.39000: Abbemat refractometers of the Heavy Duty, Performance and Performance Plus lines have a measuring range of at least 1.32 nD to 1.56 nD.
  • Resolution of 10-5 nD: Anton Paar’s refractometers have a resolution of 10-5 nD to 10-6 nD.
  • Temperature control: Abbemat refractometers very quickly achieve stable temperatures with their Peltier thermostats and have a temperature accuracy of at least 0.05 °C.

Learn more about the Anton Paar’s refractometers 

Other relevant instruments

DIN EN ISO 12185 demands the measurement of density of AdBlue® solutions, which can easily be done with Anton Paar’s DMA density meters.

Good to know

Abbemat refractometers fulfill the specifications required for refractive index measurements of AdBlue® according to ISO 22241.