RatnerPrestia
Tagging system
A method of tracing an aqueous liquid, particularly an aqueous urea used for addition to a selective catalytic reduction system to remove NOx from diesel exhaust includes adding a tracer comprising a pre-determined amount of a phenol to the liquid. The liquid can subsequently be identified by reacting a sample with a reagent containing a predetermined amount of 4-aminoantipyrine in the presence of an initiating compound such that the reaction between the reagent and a phenol in the liquid produces a chromophore and measuring the absorbance of the resulting solution of the chromophore.
Johnson Matthey PLC
Y C G G F F Y F
Y10T C01C G01N G01N F01N F01N Y02T F01N
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Darrell Andrew
Green West