Dimethylbis[(1-oxoneodecyl)oxy]stannane

Endpoint summary

Link to relevant study record(s)

Reference

Endpoint:

basic toxicokinetics in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 September 2017 to 03 November 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Objective of study:

bioaccessibility (or bioavailability)

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 111 (Hydrolysis as a Function of pH)

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)

Deviations:

no

GLP compliance:

no

Radiolabelling:

not specified

HYDROLYSIS AT PH 4,7 AND 9

Samples of the test material were added to the respective buffer solutions at 50 °C for 5 days (120 h). At no pH value did the 119Sn-NMR spectra of the extracted reaction products show signs of hydrolysis.

The half-life time of the test material under the conditions of the study was > 1 year for the pH values 4 and 7 and the test material can be considered as hydrolytically stable.

At pH 9 besides the signal for the test material a new broad signal at -200 ppm appeared with a intensity equivalent to 57 Mol% which cannot be attributed unequivocally to a specific tin containing species.

Based on the chemistry the formation of a hydroxide and possible further reaction products can be postulated.

HYDROLYSIS AT PH 1.2

1 g (2.03 mMol) of the test material was added to an excess 0.1 M hydrochloric acid at 37 °C for 4 hours and extracted with hexane after cooling down to room temperature. The 119Sn-NMR spectrum of the organic extract showed no signal between 200 and -500 ppm. A small signal at -523 ppm points to a highly coordinated tin compound or may be just an artefact.

The 1H-NMR spectrum of the hexane extract was identical with the reference spectrum of neodecanoic acid. It can be concluded that under the conditions of the study the neodecanoic acid ligand is hydrolysed from the tin atom and the dimethyltin cation forms a water soluble breakdown product.  

ATOMIC ABSORPTION SPECTOMETRY

- The aqueous phases of the low pH hydrolysis has been analysed after extraction with hexane by AAS and contained 1690 mg/L Sn.

Conclusions:

Under the conditions of this study, the test material was hydrolytically stable at pH 7 and 4. At pH 9 57 Mol % of a substance was formed which cannot be unequivocally attributed to a known tin compound. At pH 1.2 the only identifiable breakdown product was the ligand neodecanoic acid.

Executive summary:

The hydrolysis of the test material as a function of pH was investigated in accordance with the standardised guidelines OECD 111 and EU Method C.7.

The stability of the test material was investigated at pH 4, 7 and 9 and pH 1.2 using NMR spectroscopy.

The study showed that the test material is hydrolytically stable at pH 7 and 4. After 5 days of hydrolysis at 50 °C less than 10 % of the test material was hydrolysed (half life at 25 °C > 1 year). At pH 9 / 50 °C / 5 days 57 Mol % of a substance was formed which cannot be unequivocally attributed to a known tin compound. Based on the chemistry the formation of a hydroxide and possible further reaction products can be postulated.

At simulated gastric conditions (0.1 M HCl /pH 1.2 /37 °C/ 4 h) the only identifiable breakdown product was the ligand neodecanoic acid, which was extracted in the hexane phase and identified by 1H-NMR spectroscopy.

The lower recovery of substance in the hexane extract and the content of 1690 mg/L tin remaining in the aqueous phase indicate that the dimethyltin cation remains in a soluble form in water.

Description of key information

Hydrolysis as a function of pH

Under the conditions of the study, the test material was hydrolytically stable at pH 7 and 4. At pH 9 57 Mol % of a substance was formed which cannot be unequivocally attributed to a known tin compound. At pH 1.2 the only identifiable breakdown product was the ligand neodecanoic acid.

Additional information

Hydrolysis as a function of pH

The hydrolysis of the test material as a function of pH was investigated in accordance with the standardised guidelines OECD 111 and EU Method C.7.

The stability of the test material was investigated at pH 4, 7 and 9 and pH 1.2 using NMR spectroscopy.

The study showed that the test material is hydrolytically stable at pH 7 and 4. After 5 days of hydrolysis at 50 °C less than 10 % of the test material was hydrolysed (half life at 25 °C > 1 year). At pH 9 / 50 °C / 5 days 57 Mol % of a substance was formed which cannot be unequivocally attributed to a known tin compound. Based on the chemistry the formation of a hydroxide and possible further reaction products can be postulated.

At simulated gastric conditions (0.1 M HCl /pH 1.2 /37 °C/ 4 h) the only identifiable breakdown product was the ligand neodecanoic acid, which was extracted in the hexane phase and identified by 1H-NMR spectroscopy.

The lower recovery of substance in the hexane extract and the content of 1690 mg/L tin remaining in the aqueous phase indicate that the dimethyltin cation remains in a soluble form in water.