Table 3.

Oxidation markers or specific degradation products for polysorbate 20 and 80. Published oxidation markers or specific degradation products of PS20 and PS80 are summarized below. Not all identified degradation products are summarized. Only derivates, which are reported as oxidation markers or specific degradation products are listed.

Oxidation marker	Marker type	Applied stress	Molecular weighta / g·mol-1	Putative structure	Referencesb
PEGx10 peroxide	Universal	10 ppb Fe2+ & 40 °C	474.2676		Kranz et al. (2020) (Kranz et al., 2020)
PEGx9 glycolic acid ester	Universal	10 ppb Fe2+ & 40 °C	472.2520		Kranz et al. (2020) (Kranz et al., 2020)
Glycolic acid ester-PEGx2-laurate	PS20	10 ppb Fe2+ & 40 °C	346.2355		Kranz et al. (2020) (Kranz et al., 2020)
12-oxo-lauric acid	PS20	10 ppb Fe2+ & 40 °C	214.1569		Kranz et al. (2020) (Kranz et al., 2020)
9-oxo-C9:0-ester†	PS80	1.5 mM AAPH	1418.8232†		Borisov et al. (2015) (Borisov et al., 2015)
Hydroxy-C18:1-ester†	PS80	40 °C	1544.9641†		Hvattum et al. (2012) (Hvattum et al., 2012)
Hydroperoxyl-C18:1-ester†	PS80	1.5 mM AAPH	1560.959†		Borisov et al. (2015) (Borisov et al., 2015)
Keto-C18:1-ester†	PS80	40 °C	1542.9484†		Hvattum et al. (2012) (Hvattum et al., 2012)
Epoxy-C18:0-ester	PS80	40 °C	-		Hvattum et al. (2012) (Hvattum et al., 2012)
1,9-nonanedioic acid‡, ⨁	PS80	50 °C	-		Brovč et al. (2020) (Brovč et al., 2020a)
2-decenedioic acid-ester‡	PS80	Stored under air	-		Liu et al. (2022) (Liu et al., 2022a)

^aMolecular weight is given for the original structure and not for the measured adduct.

^bReference, which first reported and verified the degradation product.

^†Kranz et al. (2020) provided already published oxidation markers from Borisov et al. (2015) and Hvattum et al. (2012) including their molecular weights: esters of 9-oxo-C9:0, hydroxy-C18:1, hydroperoxyl-C18:1, and keto-C18.

^‡Specific degradation products not reported as oxidation markers.

^⨁1,9-nonanedioic acid is esterified to sorbitan-POE.