Potassium 1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulphonate

Water solubility

Description of key information

The average solubility of PFBSK+ in water at 22.5-24 °C were determined to be 52,600 μg/mL (RSD% = 1.2%) and 56,600 μg/mL (RSD% = 2.0%) for the Lot 1 and Lot 2, respectively.

Additional information

The water solubility of PFBSK+ was determined according to USEPA OPPTS 830.7840, “Water Solubility: Column Elution Method; Shake Flask Method” Guideline. Two lots (Lot 1, and Lot 2) of PFBSK+ were tested for water solubility at three time points (day 1, 2, and 3). Triplicate samples were prepared for each lot and each time point. Adequate amounts of PFBSK+ were weighed into the test vessels and sufficient water added gravimetrically to obtain an approximate total weight of 10 times of the sample weight. The samples were placed in a temperature-controlled orbital shaker set at 30 °C (29.5 -30 °C) and rotation speed set at approximately 250 rpm. At the end of each time point, the samples were removed and allowed to equilibrate at 22.5-24 °C for 24 hours and centrifuged. Four replicates of aliquots were transferred from the supernatant of each sample and diluted with a series of dilutions. The final diluted samples were spiked with THPFOS as internal standard and analyzed via HPLC/ES/MS. The overall solubilities of PFBSK+ in water at 22.5-24 °C were determined to be 52,600 μg/mL (RSD% = 1.2%) and 56,600 μg/mL (RSD% = 2.0%) for the Lot 1 and Lot 2, respectively. This is a guideline study conducted under GLP compliance. It is considered reliable without restriction and a key study.

A previous study was conducted according to OECD 105 (Water solubility). Triplicate PFBSK+ samples were prepared by adding approximately 10 g of test substance into 100 mL of water. The samples were incubated at 30 °C for 1, 2, 3 days, respectively. After incubation, the samples were equilibrated at 20 °C for 24 hours. Triplicate aliquots from each sample were transferred and centrifuged. The centrifuged subsamples had undissolved, suspended material present, therefore, aliquots of the supernatant from each subsample were transferred to plastic microcentrifuge tubes and centrifuged at ~ 13000 rpm for ~ 5 minutes. An appropriate volume was volumetrically removed from each subsample aliquot and diluted into calibration range with 50% methanol and 50% Nanopure water and analyzed by HPLC/MS. The overall water solubility for PFBSK+ was 46.2 g/L (RSD%= 0.38%), obtained by averaging the sample incubated for two and three days. This is a guideline study conducted under GLP compliance. However, the exclusion of day one data was not clear and not explained. Therefore, it is considered reliable with restrictions and a supporting study.

A third experiment was conducted according to EU method A.6 (Water solubility). Triplicate PFBSK+ samples were prepared by adding approximately 4.0 g of test substance into 80 mL of water. The samples were incubated at 30 °C for 24, 48, and 72 hours respectively. After incubation, the samples were equilibrated at 20 °C for 24 hours and centrifuged. After centrifugation, the test solutions were combusted, and the combustion gas (containing fluorine) was absorbed with diluted sodium hydroxide solution. The fluorine content was determined using a Fluoride ion selective electrode. Subsequently, the water solubility of the PFBSK+ was calculated from the measured Fluorine content. The measured PFBSK+ water solubility was 44.3 g/L (RSD = 1.7%). This is a guideline study conducted under GLP compliance. However, it lacks detailed documentation on the analytical information. Therefore, it is considered reliable with restrictions and a supporting study.