Multi-element Analysis of AUS 32 (AdBlue®) following DIN ISO 22241-2
Since 1992, when the first emission standard Euro 1 was introduced, maximum limits for the emission of air pollutants such as carbon monoxide (CO) and nitrous oxides (NOx) were set for newly registered vehicles. To meet the decreasing maximum NOx emission limits, new technologies primarily for diesel engines had to be developed.
The selective catalytic reduction (SCR) has proven effective to reduce the emission of NOx from diesel engines. Using an aqueous urea solution (AUS 32 or AdBlue®) made from 32.5% urea and deionized water  and a suitable catalyst, the emission of nitrous oxides can be reduced by up to 90% . Applying the SCR technology, AUS 32 is injected into the exhaust stream. The released ammonia reduces the nitrous oxides to nitrogen and water  at the catalyst’s surface.
DIN ISO 22241-1 to 4 regulate the quality of AUS 32 and set contamination limits for iron, sodium and potassium.