Dibutyltin oxide

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

14 January 2015 to 15 January 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The only suitable analytical method that could be used was ICP-AES. ICP-AES is not a substance-specific form of analysis as it measures the total tin content (which will include any soluble impurities). However, it is considered that since the % of impurities in the sample tested is very low the value obtained is considered to be representative.

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7840 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7860 (Water Solubility Generator Column Method)

Deviations:

no

GLP compliance:

yes

Type of method:

column elution method

Water solubility:

2.55 mg/L

Temp.:

20 °C

Remarks on result:

other: 2.55 ± 0.16 mg a.i./L (CV = 6.5 %, N = 11).The measured pH of reagent water and an aqueous sample was 6.5 and 4.4, respectively.

Details on results:

The matrix blank sample did not show any spectral interferences and background levels were significantly below the low-level calibration standard.
The temperature of the water bath remained constant at 20.0 ± 0.1 °C throughout the experiment.
Under the instrumental conditions presented, the mean measured reagent water solubility of the test material at 20 °C was 2.39 ± 0.084 mg a.i./L (CV = 3.5 %, N = 5) at a flow rate of approximately 1.0 mL/min and was 2.67 ± 0.071 mg a.i./L (CV = 2.7 %, N = 6) at a flow rate of approximately 0.5 mL/min (Table 1).
The mean test material concentration for the approximately 1.0 and 0.5 mL/min flow rate settings differed by 11 %, which was well within the ± 30 % test criterion. The overall mean measured water solubility at 20 °C was 2.55 ± 0.16 mg a.i./L (CV = 6.5 %, N = 11).
The pH was measured for an aqueous sample collected at a flow rate of 1.0 mL/min. The measured pH of reagent water and an aqueous sample was 6.5 and 4.4, respectively.

Table 1: Measured Concentration of the Test Material in Aqueous Samples Collected at 20.0 °C

Sample Number	Measured Flow rate (mL/min)	Calculated Test Material Concentration (mg/L)	Mean Calculated Concentration (mg/L)
1	1.0	2.27	2.39 ± 0.084 CV = 3.5 %
3		2.39
4		2.38
5		2.42
6		2.50
7	0.5	2.67	2.67 ± 0.071 CV = 2.7 %
8		2.70
9		2.70
10		2.60
11		2.78
12		2.59

CV = Coefficient of Variation

Overall: Mean = 2.55 ± 0.16 mg/L, CV = 6.5 % and % difference = 11 %

Conclusions:

Under the conditions of this study the water solubility of the test material in reagent water at 20 °C was determined to be 2.55 ± 0.16 mg a.i./L.

Executive summary:

The water solubility of the test material was determined in a study conducted in accordance with the standardised guidelines OECD 105, US EPA OPPTS 830.7840 and OPPTS 830.7860 under GLP conditions.

The test was performed using reagent-grade water and the column elution method as modified by use of a generator column apparatus. The test was carried out using flow rates of 1.0 and 0.5 mL/minute. The test was terminated when the mean measured concentrations of the test material at the two flow rates were determined to be within 30 % of each other.

The matrix blank sample did not show any spectral interferences and background levels were significantly below the low-level calibration standard. The temperature of the water bath remained constant at 20.0 ± 0.1 °C throughout the experiment.

Under the instrumental conditions presented, the mean measured reagent water solubility of the test material at 20 °C was 2.39 ± 0.084 mg a.i./L (CV = 3.5 %, N = 5) at a flow rate of approximately 1.0 mL/min and was 2.67 ± 0.071 mg a.i./L (CV = 2.7 %, N = 6) at a flow rate of approximately 0.5 mL/min. The measured pH of reagent water and an aqueous sample was 6.5 and 4.4, respectively.

The mean test material concentration for the approximately 1.0 and 0.5 mL/min flow rate settings differed by 11 %, which was well within the ± 30 % test criterion.

Under the conditions of this study, the overall mean measured water solubility at 20 °C was 2.55 ± 0.16 mg a.i./L (CV = 6.5 %, N = 11).

Reference 2

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

No information

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted to GLP in accordance with generally accepted scientific principles, possibly with incomplete reporting or methodological deficiencies, which do not affect the quality of the relevant results. Both runs were performed at the same flow rate. OECD Guideline 105 specifies that the second run should be performed at ½ the flow rate. The analytical method used (ICP) was not compound-specific. The solubility of the test substance was based on measurement of total tin in the samples. Measurement of total tin potentially includes any contribution(s) from more water-soluble impurities or hydrolysis products. DBTO is a hydrolysis product of the dibutyltins and is not subject to hydrolysis itself. In water, DBTO will precipitate as a stable oligomeric acid.

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Principles of method if other than guideline:

No further information required.

GLP compliance:

not specified

Type of method:

column elution method

Water solubility:

4 mg/L

Temp.:

20 °C

pH:

6.1

Details on results:

pH Concentration: 4 mg/l at 20 °C. The standard deviation is 0.15 mg/L. The repeatability of the runs is less than 20% and fulfils the required condition for repeatability <30% for the elution method.

Conclusions:

Based on the two independent runs, the water solubility of dibutyltin oxide was 4.0 ± 0.15 mg/L at 20 ºC.

Executive summary:

In accordance with OECD Guideline No. 105, the column elution method was used for the determination of the water solubility. Based on the two independent runs, the water solubility of dibutyltin oxide was 4.0 ± 0.15 mg/L .at 20 ºC.

Description of key information

The overall mean measured water solubility at 20 °C was 2.55 ± 0.16 mg a.i./L (CV = 6.5 %, N = 11).

Key value for chemical safety assessment

Water solubility:

2.55 mg/L

at the temperature of:

20 °C

Additional information

In the key study (Van Hoven et al., 2015), the water solubility of the test material was determined in a study conducted in accordance with the standardised guidelines OECD 105, US EPA OPPTS 830.7840 and OPPTS 830.7860 under GLP conditions. it was awarded a reliability score of 1 in accordance with the principles set forth by Klimisch et al. (1997).

The only suitable analytical method that could be used was ICP-AES. ICP-AES is not a substance-specific form of analysis as it measures the total tin content (which will include any soluble impurities). However, it is considered that as the registered material is the main constituent of the test material, the value obtained is considered to be representative.

The test was performed using reagent-grade water and the column elution method as modified by use of a generator column apparatus. The test was carried out using flow rates of 1.0 and 0.5 mL/minute. The test was terminated when the mean measured concentrations of the test material at the two flow rates were determined to be within 30 % of each other.

The matrix blank sample did not show any spectral interferences and background levels were significantly below the low-level calibration standard. The temperature of the water bath remained constant at 20.0 ± 0.1 °C throughout the experiment.

Under the instrumental conditions presented, the mean measured reagent water solubility of the test material at 20 °C was 2.39 ± 0.084 mg a.i./L (CV = 3.5 %, N = 5) at a flow rate of approximately 1.0 mL/min and was 2.67 ± 0.071 mg a.i./L (CV = 2.7 %, N = 6) at a flow rate of approximately 0.5 mL/min. The measured pH of reagent water and an aqueous sample was 6.5 and 4.4, respectively.

The mean test material concentration for the approximately 1.0 and 0.5 mL/min flow rate settings differed by 11 %, which was well within the ± 30 % test criterion.

Under the conditions of this study, the overall mean measured water solubility at 20 °C was 2.55 ± 0.16 mg a.i./L (CV = 6.5 %, N = 11).

This was selected as the key study as the most up to date and sensitive analytical methodology was used.

In the supporting study (Schering, 1989), the water solubility of dibutyltin oxide was determined to be 4.0 ± 0.15 mg/L at 20 ºC.

The study was conducted to recognised guidelines and according to the criteria of Klimisch et al. (1997) a reliability rating of 2 was assigned to this study.

Both runs were performed at the same flow rate. OECD Guideline 105 specifies that the second run should be performed at ½ the flow rate. The analytical method used (ICP) was not compound-specific. The solubility of the test substance was based on measurement of total tin in the samples. Measurement of total tin potentially includes any contribution(s) from more water-soluble impurities or hydrolysis products. DBTO is a hydrolysis product of the dibutyltins and is not subject to hydrolysis itself. In water, DBTO will precipitate as a stable oligomeric acid.