Sodium diisobutylnaphthalenesulphonate

Hydrolysis

Administrative data

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 02 July 2012 to April 2013

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Sodium diisopropylnaphthalenesulphonate

EC Number:

215-343-3

EC Name:

Sodium diisopropylnaphthalenesulphonate

Cas Number:

1322-93-6

Molecular formula:

C16H20O3S.Na

IUPAC Name:

sodium 2,3-diisopropylnaphthalene-1-sulfonate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

See confidential details on test material section

Radiolabelling:

no

Study design

Analytical monitoring:

yes

Details on sampling:

Aliquots from each prepared sample solution and the blank buffer solutions were analysed at the beginning of the test (day 0) and the samples and blanks stored at 50°C were analysed at the end of the test (day 5). Samples were submitted for HPLC analysis following analytical procedure PC 8265266 01V.
The pH of each prepared sample solution and each blank buffer solution was measured before and after incubation.

Buffers:

pH 4
1 ampoule of pH 4 ConVol buffer (Batch OC112733) was diluted in 1 litre of double distilled water. The pH was then tested and confirmed as 3.98.

pH 7
1 ampoule of pH 7 ConVol buffer (Batch 90350156) was diluted in 1 litre of double distilled water. The pH was then tested and confirmed as 6.99.

pH 9
500 mL of Merck Certipur pH buffer solution (Batch HC126891) was made up to1 litre with double distilled water. The pH was then tested and confirmed as 8.99.

Sterilisation
All glassware was sterilised by autoclave.

Details on test conditions:

Sample Preparation
Samples were prepared at the following concentrations:
pH Concentration Supragil WP (µg/mL) Concentration Mono (µg/mL) Concentration Di (µg/mL) Concentration Tri (µg/mL)
4 17.23 3.54 7.38 2.66
7 17.27 3.55 7.39 2.66
9 17.31 3.56 7.41 2.67

The components of Supragil WP analysed in this study are: sodium monoisopropylnaphthalenesulphonate, sodium diisopropylnaphthalenesulphonate and sodium triisopropylnaphthalenesulphonate. These will be identified as mono, di and tri, respectively.
The concentrations were achieved by diluting stock solutions with pH 4, 7 and 9 buffer solutions. From the prepared samples, two vials were filled for each pH level, along with a third vial which was filled with blank buffer for each pH level. The vials were all incubated for 5 days at approximately 50°C (actual temperature ranges measured were 50°C for the pH 4 and pH 7 test and 49.7°C to 49.8°C for the pH 9 test).

pH Measurement
The pH of each prepared sample solution and each blank buffer solution was measured before and after incubation.

Hydrolysis
For the pH 4 and pH 7 testing the samples were placed in an incubator set at 50°C ± 2°C on 24 September 2012. They were then left to stand at temperature, in the dark, until 28 September 2012 when they were removed for analysis.
For the pH 9 testing the samples were placed in a water bath set at 50°C ± 1°C on 15 October 2012. The water bath was covered and the samples were left to stand at temperature, in the dark, until 19 October 2012 when they were removed for analysis.

Sample Analysis
Aliquots from each prepared sample solution and the blank buffer solutions were analysed at the beginning of the test and the samples and blanks stored at 50°C were analysed at the end of the test. Samples were submitted for HPLC analysis following analytical procedure PC 8265266 01V.

Duration of test

Duration of test 1

Duration:

5 d

pH:

4

Initial conc. measured:

17.23 mg/L

Duration of test 2

Duration:

5 d

pH:

7

Initial conc. measured:

17.27 mg/L

Duration of test 3

Duration:

5 d

pH:

9

Initial conc. measured:

17.31 mg/L

Number of replicates:

Two vials were filled for each pH level, along with a third vial which was filled with blank buffer for each pH level.

Positive controls:

no

Negative controls:

no

Results and discussion

Preliminary study:

Less than 10% degradation of reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic soda was observed after 5 days incubation at 50.0 °C in sterile pH 4.0, pH 7.0 and pH 9.0 buffer samples. The tri at pH 4 showed a drop of 10.91%; however this was not deemed significant when the standard error of the results and the concentration of this compound in the test item was taken into account.
The test substance was considered to be hydrolytically stable (estimated half-life greater than 1 year at 25 °C) and no additional testing was performed.

Test performance:

not measured

Transformation products:

not measured

Dissipation DT50 of parent compound

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

The hydrolysis results are shown in "any other information on results incl.tables"

Any other information on results incl. tables

Table 1: Hydrolysis results

pH	Compound	Conc. T0	Mean Conc. T0	Conc. T5	Mean Conc. T5	% Change	Minimum % change (corrected for standard error)*		Maximum % change (corrected for standard error)*
4	Mono	3.87	3.89	3.79	3.76	-3.2173	T0 min value	3.87	T0 max value	3.91
				3.72			T5 max value	3.78	T5 min value	3.75
		3.91		3.78			% change	-2.41	% change	-4.01
				3.77
	Di	7.68	7.71	7.80	7.76	0.5904	T0 min value	7.68	T0 max value	7.74
				7.75			T5 max value	7.78	T5 min value	7.73
		7.74		7.69			% change	1.31	% change	-0.12
				7.80
	Tri	2.96	2.98	2.68	2.66	-10.9065	T0 min value	2.96	T0 max value	3.00
				2.67			T5 max value	2.67	T5 min value	2.64
		3.00		2.64			% change	-9.96	% change	-11.84
				2.64
7	Mono	3.86	3.86	3.73	3.76	-2.5691	T0 min value	3.86	T0 max value	3.86
				3.82			T5 max value	3.79	T5 min value	3.74
				3.71			% change	-1.85	% change	-3.28
				3.80
	Di	7.68	7.68	7.63	7.70	0.1855	T0 min value	7.68	T0 max value	7.68
				7.75			T5 max value	7.72	T5 min value	7.67
				7.71			% change	0.52	% change	-0.15
				7.71
	Tri	2.78	2.78	2.48	2.52	-9.3928	T0 min value	2.78	T0 max value	2.78
				2.49			T5 max value	2.54	T5 min value	2.50
				2.57			% change	-8.61	% change	-10.17
				2.55

 

pH	Compound	Conc. T0	Mean Conc. T0	Conc. T5	Mean Conc. T5	% Change	Minimum % change (corrected for standard error)*		Maximum % change (corrected for standard error)*
9	Mono	3.40	3.31	3.47	3.52	6.4484	T0 min value	3.28	T0 max value	3.34
		3.32		3.62			T5 max value	3.57	T5 min value	3.48
		3.24		3.58			% change	8.89	% change	4.06
		3.28		3.43
	Di	6.89	6.77	7.35	7.37	8.9210	T0 min value	6.73	T0 max value	6.81
		6.72		7.44			T5 max value	7.40	T5 min value	7.35
		6.72		7.34			% change	9.95	% change	7.90
		6.75		7.36
	Tri	2.29	2.32	2.51	2.49	7.4823	T0 min value	2.31	T0 max value	2.33
		2.32		2.49			T5 max value	2.50	T5 min value	2.48
		2.33		2.49			% change	8.29	% change	6.69
		2.34		2.48

 

The components of Supragil WP analysed in this study are: sodium monoisopropylnaphthalenesulphonate, sodium diisopropylnaphthalenesulphonate and sodium triisopropylnaphthalenesulphonate. these will be identified as mono, di and tri, respectively.

T0 minimum value = T0 mean – standard error        T0 maximum value = T0 mean + standard error

T5 minimum value = T5 mean – standard error        T5 maximum value = T5 mean – standard error

Standard error = σ_n-1/(n^1/2)

Where:

·        σ_n-1is the standard deviation of the data set

·        n is the number of values in the data set

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Less than 10% degradation of reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic soda was observed after 5 days (half-life is estimated to be greater than 1 year at 25 °C) in the sterile pH 4.0, pH 7.0 and pH 9.0 buffer samples. Reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic soda was considered to be hydrolytically stable at pH 4.0, 7.0 and 9.0 .

Executive summary:

The hydrolysis of reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic soda was studied in accordance with the OECD Testing Guideline 111 and under the GLP. No deviation from the guideline was observed in the study.

Samples were prepared at the following concentrations:

pH	Concentration reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic soda (µg/mL)	Concentration Mono (µg/mL)	Concentration Di (µg/mL)	Concentration Tri (µg/mL)
4	17.23	3.54	7.38	2.66
7	17.27	3.55	7.39	2.66
9	17.31	3.56	7.41	2.67

 

The samples were incubated for 5 days at 50°C at pH 4.0, pH 7.0 and pH 9.0 sterile aqueous buffer solutions in dark conditions. At the beginning of the test and at the end of the test, duplicate samples were analyzed by High Performance Liquid Chromatography (HPLC) with UV detection to quantify the three components of interest of the test substance (sodium monoisopropylnaphthalenesulphonate, sodium diisopropylnaphthalenesulphonate and sodium triisopropylnaphthalenesulphonate) presents in the aqueous samples.

Less than 10% degradation of reaction product of naphthalene, propan-2-ol, sulfonated and neutralized by caustic soda was observed after 5 days incubation at 50.0 °C in sterile pH 4.0, pH 7.0 and pH 9.0 buffer samples. The sodium triisopropylnaphthalenesulphonate at pH 4 showed a drop of 10.91%; however this was not deemed significant when the standard errorof the resultsand the concentration of this compound in the test item was taken into account.

The test substance was considered to be hydrolytically stable at pH 4.0, 7.0 and 9.0 and no additional testing was required or performed.