Table 3.

TOC measurements in triplicate (average ± standard deviation) and polystyrene particle recoveries before and after filtration at 0.45 µm in ultrapure water and environmental water samples spiked with PS 1000 nm and PS 50 nm

		TOCa (mg L−1) [PS recovery] (%)
	Conditions (n = 3)	UPW (referencec)	Lake Maggiore	Variola River
Unspiked samples	(1) Unfiltered	0.028 ± 0.003	0.872 ± 0.098	0.202 ± 0.139
	(2) Filtered 0.45 µm	0.094 ± 0.002	0.750 ± 0.070	0.167 ± 0.046
Spikedb samples	(3) Unfiltered	1.712c ± 0.014 [100 ± 2]	1.637 ± 0.131 [96 ± 8]	1.538 ± 0.325 [90 ± 19]
	(4) Filtered 0.45 µm	0.830c ± 0.004 [100 ± 1]	0.788 ± 0.223 [95 ± 27]	0.577 ± 0.265 [70 ± 32]

^aFor conditions (3) and (4), native TOC contribution of unspiked sample (unfiltered or filtered) was subtracted, respectively

^bUnfiltered water spiked with 1 mg L⁻¹ PS 1000 nm and 1 mg L⁻¹ PS 50 nm (theoretically equivalent to (1 + 1) × 92.26%C = 1.8452 mg L⁻¹ organic carbon addition)

^cReference TOC values for PS recoveries calculations in conditions (3) and (4), respectively