A method of evaluating and selecting a suitable chemistry for removal of microplastics in a liquid matrix, said method comprising the steps of: a. providing a predetermined volume of a liquid matrix, b. adding a preset amount of a chemical system comprising at least one coagulant and/or flocculant to the liquid matrix of step a), and allowing the added chemical system to interact to form flocs and/or aggregates containing any microplastic particles, if present in the liquid matrix, c. removing flocs and/or aggregates containing any microplastic particles of the liquid matrix in a separation step to form a clarified liquid matrix, d. measuring fluorescence intensity and light scattering intensity of any particles in a sample volume of clarified liquid matrix by an optical measurement, d'. gathering and combining the scattering intensity data and the fluorescence intensity data of the particles, d". identifying particle populations of the measured data representing microplastic particles populations based on predetermined identification data, d′′′. determining the number of microplastic particles of the microplastic particles populations, e. assessing the efficiency of microplastics removal based on: the number of microplastic particles in the sample volume used in step d), or the number of microplastic particles in the sample volume used in step d) compared to a known number of microplastic particles, if used, added to the liquid matrix in step a); wherein steps a) to e) are repeated a number of times with other chemical systems than said at least one chemical system, and further comprising the steps of: f. comparing the efficiency of microplastics removal of all chemical systems tested, and g. selecting a suitable chemical system for the desired removal efficiency in a liquid matrix. a. providing a predetermined volume of a liquid matrix, b. adding a preset amount of a chemical system comprising at least one coagulant and/or flocculant to the liquid matrix of step a), and allowing the added chemical system to interact to form flocs and/or aggregates containing any microplastic particles, if present in the liquid matrix, c. removing flocs and/or aggregates containing any microplastic particles of the liquid matrix in a separation step to form a clarified liquid matrix, d. measuring fluorescence intensity and light scattering intensity of any particles in a sample volume of clarified liquid matrix by an optical measurement, d'. gathering and combining the scattering intensity data and the fluorescence intensity data of the particles, d". identifying particle populations of the measured data representing microplastic particles populations based on predetermined identification data, d′′′. determining the number of microplastic particles of the microplastic particles populations, d'. gathering and combining the scattering intensity data and the fluorescence intensity data of the particles, d". identifying particle populations of the measured data representing microplastic particles populations based on predetermined identification data, d′′′. determining the number of microplastic particles of the microplastic particles populations, e. assessing the efficiency of microplastics removal based on: the number of microplastic particles in the sample volume used in step d), or the number of microplastic particles in the sample volume used in step d) compared to a known number of microplastic particles, if used, added to the liquid matrix in step a); wherein steps a) to e) are repeated a number of times with other chemical systems than said at least one chemical system, and further comprising the steps of: f. comparing the efficiency of microplastics removal of all chemical systems tested, and g. selecting a suitable chemical system for the desired removal efficiency in a liquid matrix. the number of microplastic particles in the sample volume used in step d), or the number of microplastic particles in the sample volume used in step d) compared to a known number of microplastic particles, if used, added to the liquid matrix in step a); wherein steps a) to e) are repeated a number of times with other chemical systems than said at least one chemical system, and further comprising the steps of: f. comparing the efficiency of microplastics removal of all chemical systems tested, and g. selecting a suitable chemical system for the desired removal efficiency in a liquid matrix. f. comparing the efficiency of microplastics removal of all chemical systems tested, and g. selecting a suitable chemical system for the desired removal efficiency in a liquid matrix.