This application note gives a complete solution for determining the aldehyde content in AdBlue® diesel exhaust liquid by measuring the absorbance of aldehyde-chromotropic acid complex using METTLER TOLEDO UV Vis spectrophotometer.
What is AUS32 Solution?
Combustion of diesel engines generally exhausts more nitrogen oxides (NOx) into the atmosphere. NOx has an adverse impact on the environment causing smog formation, acid rains or depletion of the ozone layer in the atmosphere. Reducing the level of NOx in the atmosphere is of utmost importance. One of the methods to minimize the release of NOx is by reducing it into nitrogen and water through the combustion process. Such reactions demand a catalyst and urea is quite an effective one for the above mentioned reduction process. Urea solution in water (AUS 32) is sprayed into the exhaust tank for reducing the NOx gases. This urea solution is termed AdBlue® globally.
One of the quality parameters of AUS 32 solutions is the content of free and bound aldehydes expressed as formaldehyde (HCOH). The amount of aldehydes typically found in AUS 32 samples ranges from 0.5 to 10 mg/kg.
How to Evaluate the Aldehyde Content?
Aldehyde forms a purple-colored complex with chromotropic acid in strong sulfuric acid solutions. Absorbance values of this colored complex measured at 565 nm using UV Vis spectrophotometer can be used to evaluate the concentration of aldehyde.
Download our free application note to learn more and benefit from our experience in determining the aldehyde content in AdBlue® diesel.
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