A summary of the LODs for all presented submicron- and nanoplastics on SERS substrates composed of AuSpheres and AuStars. In addition to mass based LODs, the lowest concentration measured is reported as an estimated total number of particles within the final sample drop applied to the substrate. PE and PP particle number values are reported for the drop applied at stock concentration for comparison.

Plastic sample	SERS LOD on AuSpheres (μg mL−1)	Approximate plastic particle number on AuSpheres	SERS LOD on AuStars (μg mL−1)	Approximate plastic particle number on AuStars
161 nm PS	10a	9.84 × 109	0.625	3.08 × 108
33 nm PS	20a	4.24 × 107	1.25	1.32 × 106
36 nm PET	20	5.89 × 109	5	7.36 × 108
121 nm PP	Not detectable	2.46 × 107	Not detectable	1.23 × 107
126 nm PE	Not detectable	2.04 × 107	Not detectable	1.02 × 107

^aData adapted from Caldwell et al., Nanomaterials, 2021.²³