Naphthalenesulfonic acid, di-C9-rich C8-10-branched alkyl derivs., calcium salts

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Start : 19 March 2012 Completion : 29 June 2012

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

column elution method

Water solubility:

0.266 mg/L

Temp.:

19.9 °C

pH:

>= 7.4 - <= 7.5

Details on results:

The results for the samples taken at a flow rate of 12 ml/hour and 24 ml/hour are given in the attached Table.
The concentration of test substance analysed during the first experiment at 24 ml/hour (samples 1-10) are higher than those obtained with a flow rate of 12 ml/hour. Furthermore, the concentrations show a clear trend to decreasing concentrations. This indicates incomplete equilibration of the column. Therefore, calculations will be based on the experiment at 12 ml/hour and the second experiment at 24 ml/hour.
The coefficient of variation (CV) (n = 10) obtained was ≤ 30% at the flow rate of 12 ml/hour and the second application of a flow rate of 24 ml/hour. The maximum difference (MD) on the mean values of the samples at both flow rates was also ≤ 30%. Based on this, it was concluded that the system was equilibrated and the water solubility of the test substance is given as the mean value of these measurements.
The turbidity of the eluates was < 0.2 NTU. According to this, no undissolved particles were detected in the eluates.
A small response was observed in the samples from the blank column at the retention time of the test substance. The concentration was < 2 μg/l (taking a dilution factor of two into account).

Conclusions:

Interpretation of results: slightly soluble (0.1-100 mg/L)
The water solubility of the test substance at 20°C was 0.266 mg/l. The substance is slightly soluble in water.

Executive summary:

The water solubility of Calcium bis( di C8-C10, branched, C9 rich, alkylnaphthalene sulphonate) was determined following OECD Guidelines for the Testing of Chemicals no. 105: "Water Solubility", July 27, 1995.

Methods

Preliminary test

Test substance was stirred with double distilled water at a nominal concentration of 0.301 g/l at 20.0 ± 0.3°C for 92 hours (4 days). After stirring, the water phase was centrifuged, treated and analysed. In the preliminary test the water solubility of the test substance was < 0.1 g/L. Therefore, the column elution method was chosen for the main study.

Main study

A solution with an absolute test substance quantity of 68.1 mg was prepared in acetone. The solution was mixed with 5 g LiChroprep Si 60 25-40 μm column material (Merck, Darmstadt, Germany). Acetone was completely evaporated at 35°C using a rotary evaporator. The loaded carrier material was stored overnight at room temperature. A 150 mm × 4.6 mm i.d. column was filled with the carrier material and 0.5 μm frits were used to enclose the column. Double distilled water was pumped through the column until it was completely filled. The system was allowed to equilibrate for two hours. After the equilibration period, the column was eluted overnight with double distilled water at a flow rate of 12 ml/hour. The following day the flow was increased to 24 ml/hour. Ten consecutive samples of 2 ml were taken (samples 1-10). The flow was halved to 12 ml/hour and ten consecutive samples of 1 ml were taken (samples 11-20). The lower concentrations found in the samples taken at a flow of 12 ml/hour indicated that during sampling at 24 ml/hour the system had not been stable. Based on this, one day later the flow rate was doubled to 24 ml/hour and ten consecutive samples of 2 ml were taken (samples 21-30). Analysis was performed on subsamples of 750 μl. The samples were diluted in a 1:1 (v:v) ratio with acetonitrile and analysed. The pH was measured from the water fractions that were collected for the determination of the flow rates. To 1.8 ml of each fraction 0.2 ml 0.1 M sodium chloride was added in order to obtain a high electrolyte concentration for accurate pH measurement. The eluates were checked for the presence of undissolved particles using a turbidimeter. The experiment was also performed using a column filled with blank carrier material. The procedure was identical to the procedure used for the column loaded with test substance. At each flow rate, two consecutive samples were taken for analyses. The column elution method was performed at 19.9°C ± 0.3°C.

Results

The results for the samples taken at a flow rate of 12 ml/hour and 24 ml/hour are given in the attached Table. The concentration of test substance analysed during the first experiment at 24 ml/hour (samples 1-10) are higher than those obtained with a flow rate of 12 ml/hour. Furthermore, the concentrations show a clear trend to decreasing concentrations. This indicates incomplete equilibration of the column. Therefore, calculations will be based on the experiment at 12 ml/hour and the second experiment at 24 ml/hour. The coefficient of variation (CV) (n = 10) obtained was ≤ 30% at the flow rate of 12 ml/hour and the second application of a flow rate of 24 ml/hour. The maximum difference (MD) on the mean values of the samples at both flow rates was also ≤ 30%. Based on this, it was concluded that the system was equilibrated and the water solubility of the test substance is given as the mean value of these measurements. The turbidity of the eluates was

Conclusions

The column elution method was applied for the determination of the water solubility of Calcium bis( di C8-C10, branched, C9 rich, alkylnaphthalene sulphonate). The water solubility of the test substance at 20°C was 0.266 mg/l. The pH of the aqueous samples was 7.4 – 7.5. The substance is slightly soluble in water.

Description of key information

The water solubility of the test substance at 20°C was 0.266 mg/l.

Key value for chemical safety assessment

Water solubility:

0.266 mg/L

at the temperature of:

20 °C

Additional information

The substance is slightly soluble in water.