Experimental block diagram, showing overall workflow (top) and the experimental design and apparatus (bottom).  Treatments A-F are as follows: A) water only (negative control); B) water + OP (negative control 2); C) water + standardized polyethylene spheres (positive control); D) water + collected microplastic spheres (experimental sample); E) polyethylene spheres + OP (positive control 2); and F) water + microplastic sphers + OP.  Samples E and F are for HOP/EDX analysis, described in section 4.2.  Additional cuvettes can be added for additional OPs, and all samples will done in triplicate.  OP = Organic pollutant.