Table 1.

Overview of preparation approaches for nC₆₀-stock suspensions and characteristics of the colloidal fullerenes

Ref.	Preparation		Characterization		Quantification
	Stock suspension	Filter	Size (nm)	Charge (mV)	Conc. (mg/L)	Method
[62]	Solvent exchange	NR	250–350	NR	1.512	NR
	ben/C60 + THF + acetone + UPW
[63]	Solvent exchange + co-solubilization	NR	NR	NR	400	Nominal
	ben/C60 + CLF + PVP + UPW + son.
[56]	Solvent exchangea	0.45 μm, c	62.8	−30	NRd	LLE-UV
	THF/C60 + UPW	PTFE
[55]	Solvent exchange
	Tol/C60 + THF + acetone + UPW	NR	20–168	−50f	151–1 498	NR
	THF/C60	NR	249	NR	NR	NR
[22]	Solvent exchange	0.22 μm, cellulose acetate	60–120e	−36 (at pH 5.0)	NR	LLE-LC/UV
	THF/C60 + UPW + rotary evap.				NR	TGA
[24]	Solvent exchangea	0.22 μm, c Nylon & cellulose	50–150	NR	2–15	LLE-UV
	THF/C60 + UPW + rotary evap.
	Sonication	0.45 & 0.22 μm, nylon & cellulose	<10–25	NR	2–15	LLE-UV
	tol/C60 + UPW
	Stirring	0.45 & 0.22 μm, nylon & cellulose	30–100	NR	2–15	UV
	2–4 weeks, in UPW at 40°C
	Co-solubilization	0.45 & 0.22 μm, nylon & cellulose	<10–25	NR	2–15	UV
	tol/C60 + CLF + PVP + UPW
[37]	Solvent exchange	0.22 μm, c nylon	NR	NR	3.10	LLE-LC/UV
	THF/C60 + UPW + rotary evap.
[47]	Solvent exchange
	tol/C60 + THF + acetone + UPW + dist.	NR	170±20	−30	3.5	NR
	THF/C60 + UPW + rotary evap.	0.22 μm, c Nylon	160±20	−50	6	NR
	tol/C60 + UPW + son.	0.45 μm, Type NR	160±20	−30	9	NR
	Stirring	0.45 μm, Type NR	180±20	−30	5	NR
	2 weeks
[42]	Grinding	NR	235	−39.0 ±1.4	473	NR
	Ground C60 + UPW + SDS + son.
[60]	Solvent exchange	NR	NR	NR	50 (31b)	Nominal (LLE-LC/MS)
	DMSO/C60 + UPW + son.
[44]	Solvent exchange	0.45 μm, Type NR	121.8 ±0.8	−31.6 ±2.3	4.20 ±0.86	LLE- LC-MS
	EtOH/C60 + UPW + son. +rotary evap.
	Stirring	0.45 μm, Type NR	178.6 ±1.2	−13.5 ±1.1	0.22 ±0.07	Evap-UV
	2 weeks – 11 months		211.8 ±1.9	−44.5 ±0.4	0.23 ±0.05	UF-UV
[41]	Stirring	NR	513–1270	−61.8 to −43	250	NR
	13 days in 10 mM NaCl, pH = 4,7,10
[64]	Solvent exchange	0.7 μm, glass fiber	60–70	−44 (at pH 7.2)	87.3	TGA
	tol/C60 + UPW + EtOH + son.
[43]	Solvent exchange	NR	120–250	−54 to −48 (at pH 7.0)	50	Nominal
	tol/C60 + UPW + N2 purging
	Stirring	Settling + 10 μm, type NR	380–580g	NR	50	Nominal
	4 weeks in UPW, SDS, or NOMg
[1]	Stirring	NR	360 ±210	NR	NR	NR
	5 weeks in UPW
[48]	Sonication	0.45 & 0.22 μm,	50.5 ±1.0	−40 to −20 (at pH 5.5)	11.62	TOC
	tol/C60 +UPW + EtOH + son.	Cellulose
	Stirring	0.45 & 0.22 μm, cellulose acetate & cellulose nitrate	83.1	−60 to −30 (at pH 5.5)	3.34	TOC
	40 days
[15]	Sonication
	Corn oil/nC60	NR	234–3124	NR	NR	NR
	Saline/nC60	NR	407–5117	NR	NR	NR
[65]	Solvent exchange	0.45 μm, type NR	73–191	−40	NR	LLE-UV/Vis
	tol/C60 + UPW + EtOH + son.
[51]	Sonication	0.45 μm, cellulose acetate	130 ±1	−40 ±1	1.7 ±0.12	LLE-LC/MS
	Ground C60 + son.

ben, benzene; CLF, chloroform; Conc., concentration; dist., distillation; DMSO, dimethylsulfoxide; EtOH, ethanol; Evap., evaporation; LC-UV, online ultraviolet spectroscopy following liquid chromatography; LLE, exhaustive liquid-liquid extraction; ¹³C NMR, nuclear magnetic resonance targeting ¹³C; NOM, natural organic matter; Nominal, weighed mass per added volume of solvent; NR, information was not reported; MS, mass spectrometry; PTFE, polytetrafluoroethylene; PVP, polyvinylpyrrolidone; rotary evap., rotary evaporation; SDS, sodium dodecyl sulfate; son., sonication; TGA, thermogravimetric analysis; THF, tetrahydrofuran; tol, toluene; TOC, total organic carbon analysis; UF, ultrafiltration; UPW, ultrapure water (18.2 MΩ/cm); UV, ultraviolet spectroscopy measurement in 1 cm cuvette.

^aunder anoxic conditions;

^bafter exhaustive LLE the concentration was 60% of the nominal concentration;

^cfiltration prior to addition of water;

^dmore than 75% of C₆₀ remained in water, a yellow film was observed sticking to the glass wall of the vial;

^epH 10.25–3.75;

^fat 10 μM NaCl pH 7.0;

^gin the presence of 50 and 5 mg/L-C NOM, respectively.