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Environmental fate & pathways

Phototransformation in air

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Description of key information

Initially, TBBPA decreased rapidly with a half-life of about 0.12 day. However, after 0.25 day of UV exposure, the rate of degradation decreased. The half-life of the second phase was determined to be 1.1 day.

Key value for chemical safety assessment

Half-life in air:
0.12 d

Additional information

To investigate photolysis of the test material, 14-C TBBPA applied to a silica gel surface was irradiated with 254 nm UV light. Five µL of acetone solution containing 2.68 µg of 14C TBBPA was applied to a thin layer chromatography plate, with 8 replicates in total. This plate was placed a short wave UV light in a Chromato-Vue TLC viewing box. Acetone droplets were covered with aluminium foil at predetermined times during UV exposure.

To determine degradation products of 14C TBBPA photolysis, larger amounts of the substance were applied to plates and irradiated for 5 days. After this, residues were scraped, eluted with acetone and subjected to analysis.

Initially, TBBPA decreased rapidly with a half-life of about 0.12 day. However, after 0.25 day of UV exposure, the rate of degradation decreased. The half-life of the second phase was determined to be 1.1 day.

TBBPA was rapidly degraded to at least 8 degradation products. All of the degradation products detected by TLC analysis were transitory; that is, each product reached a maximum after about 1 day of UV irradiation and then gradually decreased upon further irradiation. Four of the degradation products were identified by mass spectrometry: 4-(2-(3-amino-5-bromo-4-methoxyphenyl)propan-2-yl)-2,6-dibromophenol, 1,3-dibromo-5-isopropyl-2-methoxybenzene, 2,6-dibromo-4-(1-hydroxypropan-2-yl)phenol and 2,6-dibromo-3,5-dihydroxy-4-iminocyclohexa-2,5-dien-1-one.