The ubiquitous presence of small plastic particles and fibers ( To overcome this limitation we present a novel approach to measure, characterize and quantify microfibers and -particles concentrated onto membrane filters within one measurement. FTIR imaging was extended to fibers via a specialized sample handling to fix the fibers in the focal plane of the instrument. Further, after the automated analysis, an analytical procedure via Image Analysis was developed. Potential fibers were preselected from the dataset and further investigated. Different parameters allowed a detailed investigation with regard to object shape to differentiate small particles from short fibers. Afterwards, the fibers are investigated for each individual polymer type, their length and abundances. Via a filament closing process small gaps within larger fibers are closed to exclude an overestimation by overlaying objects. Subsequently the procedure was applied on datasets from studies of treated waste water to investigated type and number of micro-fibers and –particles within the effluent of the treatment plans. As first result in all of the investigated samples cellulose fibers were found. Moreover, synthetic fibers of different polymer types were successfully identified and consisted mainly of polyethylene, polypropylene, polyacrylates and polyamide. With this dataset we could show that we developed a versatile and easily applicable tool for the investigation of micro litter. The automated analysis of microfibers and –particles within one measurement further improved the necessary harmonization of microplastic research to lead to the implementation of standardized operational protocols (SOP) in the future.