Fig. 1.

The scheme detailing the three main components of a system engineering approach is meant to be read from the kernel (the “black box”) of a yet to be analysed MP sample. Under the overall goal of enabling a sample to be submitted for efficient microspectroscopic particle identification, the main objectives are the near-complete reduction of natural substances and the preservation of the contained MP. Users requirements (UR, placed around the kernel) formulate typical considerations of MP researchers working under these objectives. They are summarised here by the targets of a QuEChERS approach. One or more UR define a system requirement (SR, in rounded boxes) that specifies what a solution must provide in order to achieve the UR targets. The coloured circles indicate which SR are derived from which UR. Finally, the approach culminates in technical specifications (TS) that satisfy the previously defined requirements. Part of the solutions are the equipment (chemicals, laboratory set up, devices) and procedures used, presented here together as protocols or manuals ready for MP laboratory work (m0–m6).