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Environmental fate & pathways

Hydrolysis

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Endpoint:
hydrolysis
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Principles of method if other than guideline:
Hydrolysis pre-test
GLP compliance:
no
Radiolabelling:
no
Analytical monitoring:
yes
Details on sampling:
Samples were taken and analysed after 1, 5, 48 and 96 hours. Measurements were carried out in duplicate.
Details on test conditions:
Analysis of WAF

Organic ligand:

2 litres of a phosphate-buffer (pH 7) were mixed with 1 mL of Karstedt-concentrate and stirred for 24 hours. For the analysis of the water accommodated fraction samples were taken after 24 h of stirring. The analyte was extracted from the buffer by BME solvent with a ratio of 45 mL of buffer to 5 mL of BME solvent to which 5 μL (98 ng/mL) of internal standard (IS) in BME solvent were added. The samples were then shaken for 30 min and centrifuged subsequently. 1 mL of the organic phase was transferred into a 1 mL-GC-vial and analysed directly via GC-MS. The analysis was carried out in quadruplicate.

Platinum:

Platinum in aqueous samples was quantified, detected and evaluated at the isotope 194 in the so-called high-helium mode (194Pt [3]) of the ICP-MS to exclude interferences as much as possible. Prior to analysis the samples were acidified for stabilisation (2.5 mL concentrated nitric acid added to 20 mL of sample). A commercially available solution was used as platinum standard, containing 1000 mg/L Pt. This standard solution was used to prepare appropriate stock solutions and subsequently calibration solutions. All calibration standard solutions were acidified to a target concentration of 10 % HNO3.

Hydrolysis study

4.3 mg of Karstedt concentrate was weighed into a 100 mL volumetric flask and filled
with phosphate buffer pH 7 to the ring mark. The solution was transferred into a 2 L bottle and the volumetric flask was rinsed about 10 times with the buffer transferring the solvent to the bottle and subsequently filling the bottle up to 2 L with the phosphate buffer. Samples were taken and analysed after 1, 5, 48 and 96 hours. Measurements were carried out in duplicate.
Duration:
96 h
pH:
7
Preliminary study:
Preliminary study only was conducted.

1 hour:
Platinum concentration (run 1; run 2): 710 µg L-1; 650 µg L-1
Organic ligand concentration (run 1; run 2): 56.75 µg L-1; 59.46 µg L-1
5 hour
Platinum concentration (run 1; run 2): 700 µg L-1; 730 µg L-1
Organic ligand concentration (run 1; run 2): 40.65 µg L-1; 40.87 µg L-1
48 hour
Platinum concentration (run 1; run 2): 360 µg L-1; 360 µg L-1
Organic ligand concentration (run 1; run 2): 24.7 µg L-1; 22.69 µg L-1
96 hour
Platinum concentration (run 1; run 2): 270 µg L-1; 260 µg L-1
Organic ligand concentration (run 1; run 2): 19.01 µg L-1; 18.16 µg L-1
Conclusions:
It appears from the preliminary results that platinum and the organic ligand dissociate and over time concentrations of the organic ligand decrease, potentially due to further hydrolysis. As it is not possible to analyse the whole parent test item a full hydrolysis study was not conducted for this substance.
Executive summary:

A preliminary hydrolysis study was conducted (Kotthoff 2016). It appears from the preliminary results that platinum and the organic ligand dissociate and over time concentrations of the organic ligand decrease, potentially due to further hydrolysis. As it is not possible to analyse the whole parent test item a full hydrolysis study was not conducted for this substance.

Description of key information

A preliminary hydrolysis test was conducted with the test item. It appears from the preliminary results that platinum and the organic ligand dissociate and over time concentrations of the organic ligand decrease, potentially due to further hydrolysis. A full hydrolysis study was not conducted as it is not considered to be technically feasible.

Key value for chemical safety assessment

Additional information

A preliminary hydrolysis study was conducted with the test item (Kotthoff 2016) and based on the results of this study conducting a full hydrolysis study is considered to be technically not feasible. In order to conduct a full hydrolysis test, analysis of the parent substance is required. In the preliminary test, LC and GC-based methods were used to analyse the organic ligand, and ICP-MS was used to analyse for platinum. It appears from the preliminary results that platinum and the organic ligand dissociate and over time concentrations of the organic ligand decrease, potentially due to further hydrolysis. A full hydrolysis study assesses hydrolysis of the parent substance initially, at a range of pH values. As no analytical method is available for analysing the parent substance as a whole in this case it would not be possible to determine hydrolysis of the parent and conducting the full study is considered to be technically not feasible. Results from the preliminary hydrolysis study analysing separately for platinum and the organic ligand are reported as supporting information.