Vacutrainer for heating oil detection in Diesel fuel. The reagent is at the bottom part underneath the Diesel/heating oil mixture. Even in the left Vacutrainer the reagent changed its color into very light red although there is just a small amount of Diesel/heating oil mixture.
<a href="https://de.wikipedia.org/wiki/Benutzer:Delphin_74" class="extiw" title="de:Benutzer:Delphin 74">Delphin 74</a>
CC BY-SA 3.0
<span class="int-own-work">Self-photographed</span>