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EC number: 233-036-2 | CAS number: 10025-67-9
Hydrolysis
Administrative data
Link to relevant study record(s)
Description of key information
In a study according to OECD 111 hydrolysis was found to be rapid. Half lives were < 2 min (pH4), < 2 min (pH7) and < 2 min (pH9). Hydrolysis products indentified were elementary sulphur, sulphide, sulphate, sulphite, thiosulphate and chloride.
Key value for chemical safety assessment
- Half-life for hydrolysis:
- 2 min
- at the temperature of:
- 20 °C
Additional information
The substance is reported in the literature to undergo rapid hydrolysis in aqueous conditions. A guideline test was performed according OECD TG 111 (Hydrolysis as a Function of pH) to verify fast and quantitative hydrolysis in water. As the hydrolysis was known to occur rapidly, hydrolysis behaviour of the substance in aqueous solutions was investigated in a Tier 1 test at room temperature instead of 50 °C, at different pH (4, 7 and 9). The main hydrolysis products expected are chloride, sulfide, sulfur dioxide, sulfite, sulfate, thiosulfate and sulfur.
The following analytical methods were used to detect different hydrolysis products: chloride, sulphite, sulphate and thiosulphate were quantified via ion chromatography; sufide was determined iodometrically and precipitable sulphur was identified by Raman-Spectroscopy and determined by ICP-OES analysis.
As expected, the hydrolysis is rapid and quantitative. Due to the observed rapid and complete degradation of the substance between sample preparation and injection into ion chromatography apparatus, no precise half-life could be calculated. At 23 °C (room temperature) the half-life was calculated to be < 2 minutes for all pH investigated (4, 7 and 9). Recoveries based on the contents of chloride and total Sulphur were in the range of 97.7 to 101.7 %, indicating quantitative hydrolysis.
The total sulphur fraction was further investigated at different time points and dependent on the pH (4, 7 or 9) contained ca. 9.8 – 25% perceptible sulphur; 6.3 - < 4.2% sulphite; < 3.5% sulphate; 15.1 – 60% thiosulfate. Based on the mass balance additional volatile sulphur species as sulphur dioxide are also likely to be present, but were not specifically monitored.
The analytical method for determination of sulfide (iodometry) is not a specific method for testing hydrolysis reactions. The performed procedure resulted in an extreme sulfide concentration (expected influence of equilibrium reaction). Therefore the recovery values reported for sulphide (3.1 – 12.2 %) should be taken as qualitative figures.
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