Simplified Measurement of Coumarin in Diesel Oil

In Japan, diesel oil is subject to a consumption tax (national tax) and a diesel oil delivery tax (regional tax). However, kerosene and low-sulfur / high-sulfur A fuel oil are not subject to the delivery tax. Therefore, to avoid the tax, some vendors have been known to sell fraudulent diesel oil that has been mixed with kerosene or fuel oil. As a countermeasure, starting in March 1991, the then Ministry of Trade and Industry required addition of a 1 ppm concentration of coumarin to commercial kerosene and low-sulfur / high-sulfur A fuel oil products, so that they can be easily identified. Consequently, local tax bureaus have been using this marker for inspecting diesel oil by random sampling.
Here we show the example of simplified measurement of coumarin in diesel oil.