In this process, trace substances are solubilized by selective chemical reactions as a dye and then detected in a highly sensitive manner in a so-called "liquid core waveguide" in long-path absorption.

In the development of the devices, an emphasis is placed on the avoidance of cross-sensitivity to other traces of traces (interferences).

• Development of the world's most sensitive measuring instrument for the detection of nitrous acid (HONO) with a detection limit of 0.2 ppt (1 ppt corresponds to one particle to 10¹² = 1.000.000.000.000 air particles)
• Development of a very sensitive HNO₃ -measuring instrument (detection limit approx. 2 pptV)
• Development of a very sensitive NO₂ -measuring instrument (detection limit approx. 1 pptV)
• Development of a Combined measuring instrument for the simultaneous detection of O₃ , NO₂ and NO (running project).