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Physical & Chemical properties

Water solubility

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The water solubility of constituents of hydrogenated rosin alcohols was found to be in the range of 0.00148 – 0.292 mg/L (individual values: dihydroabietol 0.00812 mg/L, tetrahydroabietol 0.0203 mg/L, dehydroabietol 0.292 mg/L, and hydrogenated methyl esters 0.00148 mg/L).

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The water solubility of hydrogenated rosin alcohols was determined in a GLP-compliant study following OECD guideline 105, column elution method (Scymaris 2020). As the test item is a UVCB, solubility was determined for each of the four main constituent groups (tetrahydroabietol, dehydroabietol, dihydroabietol and rosin, hydrogenated, methyl esters). Two experimental runs were performed; in each, sand dosed with the test item in acetone was packed into duplicate columns and the acetone completely evaporated prior to starting the column flow. The eluate was extracted, derivatised and analysed by GC-MS. In run 1, column 1 had a flow rate of 25 mL/hour and column 2 had a flow rate of 12.5 mL/hour. As analysis of the water samples showed that for all but one constituent group (dehydroabietol) the water solubility was below or very close to the limit of quantification, the column size and flow rate was increased in run 2, to collect larger volume water samples to lower the level of quantification. The flow rates of the columns used in run 2 were 360 mL/hour and 180 mL/hour. The mean solubility values for each constituent did not differ by more than 30% between the two different flow rates studied, therefore the solubility results are considered valid. The water solubility of hydrogenated rosin alcohols was found to be in the range of 0.00148 – 0.292 mg/L (individual values: dihydroabietol 0.00812 mg/L, tetrahydroabietol 0.0203 mg/L, dehydroabietol 0.292 mg/L, and hydrogenated methyl esters 0.00148 mg/L).

In a supporting study following EU method A6 and OECD guideline 105, flask method, a water solubility value of 0.199 mg/L at 20°C was determined for the whole test item (Harlan Laboratories 2011). Three samples were prepared with 0.51 – 0.55 g test item in 1000 mL distilled water, before being shaken at 30°C, then left to stand at 20°C for at least 24 hours, before being centrifuged at 1000 rpm for 15 minutes and the resulting solution analysed by gas chromatography. A mean value from the three samples was reported, but individual solubilities of different constituents within the UVCB were not reported in this study.

The solubility of the constituents present in hydrogenated rosin alcohols has also been assessed using different QSAR models, the EPISuite models WSKOWWIN and WATERNT, SPARC and Chemicalize by ChemAxon (wca 2020). The structures for twelve representative constituents, covering each of the four constituent groups of the substance (tetrahydroabietol, dehydroabietol, dihydroabietol and rosin, hydrogenated, methyl esters), were run through the QSAR models. Overall, the QSAR predictions showed that all constituents of hydrogenated rosin alcohols are of low solubility, with the methyl ester constituents generally the least soluble, which agrees with the measured results from Scymaris (2020).The reliable QSAR predictions ranged from 0.001317 to 0.3456 mg/L for the constituents of hydrogenated rosin alcohols.