Sodium octane-1-sulphonate monohydrate

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

16 January 2018 - 12 March 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Remarks:

Study was conducted in accordance with international guidelines and in accordance with GLP. All guideline validity criteria were met.

Qualifier:

according to guideline

Guideline:

other: EU Method A.8. (Partition Coefficient - Estimation Method (Solubility Ratio))

Version / remarks:

Regulation (EC) 440/2008 of 30 May 2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

estimation method (solubility ratio)

Partition coefficient type:

octanol-water

Analytical method:

other: Not applicable

Key result

Type:

log Pow

Partition coefficient:

< -2.25

Temp.:

19.8 °C

Remarks on result:

other: Estimated value.

Remarks:

Estimation method using solubility ratios.

Data Evaluation:

The partition coefficient is estimated from the ratio of the solubilities of the test item in the pure solvents.

P_{OW estimate} = saturation c_n-octanol/ saturation c_water

Table 1:       Solubility in n-octanol (at 19.8 °C)

Weight of Test Item (mg)	Volume n-octanol	Duration of Shaking	Remarks
31.5 mg	25 ml	10 min	not dissolved
	50 ml	10 min	not dissolved
	125 ml	10 min	not dissolved
	250 ml	10 min	not dissolved
	500 ml	10 min	not dissolved
	550 ml	overnight	not completely dissolved, (therefore solubility < 55.3 mg/L)

The critical micelle concentration of the test item was measured using ISO 4311:1979 and mean measured value of 9,836 mg/l was determined⁽¹⁾.  As the test item is surface active⁽²⁾, the critical micelle concentration of the test item is used as a surrogate value for water solubility.

The POW is estimated as  "max possible saturation conc. n-octanol/saturation conc. water"

i.e. POW = < 55.3 mg/L/9800 mg/L  = < 0.0058.

The log POW is calculated to be < log 0.0058 = < - 2.24.

As the limit of the log Pow of the shake flask method is - 2, the log POW of the test item can therefore be stated as <   2.

⁽¹⁾Anon (2017): "Use of processor Tensiometer K100 in combination with the double dosing unit for characterization of cristical micelle concentrations", Source: KRÜSS GmbH, Borsteler Chaussee 85, 22453 Hamburg, Germany. Unpublished report, Report No.: Not Applicable.

⁽²⁾ Anderson, D. (2018): “Surface Tension Determination of Sodium octane-1-sulphonate” Source: ECOLAB, 370 Wabasha Street North, St. Paul, MN 55102-1390, USA. Unpublished report, Report No.: Not Applicable.

Conclusions:

The partition coefficient of the test item was estimated to be Log Pow = < - 2.25 at a temperature of 20 ± 1.0 °C.

Executive summary:

EU Method A.8.  – The partition coefficient of the test item was determined using the estimation method (solubility ratio).  The procedures employed were designed to be compatible with Method A.8., partition coefficient, of Commission Regulation (EC) No 440/2008 of 30 May 2008.

An aliquot of test item (31.5 mg) was placed in a glass vessel, n-octanol was added in a stepwise manner.  After each addition of n-octanol, the vessel was shaken for at least 10 min.  The sample was then visually checked for undissolved test item.  If the test item was not dissolved further n-octanol was added in the manner previously described.  The test was performed at 19.8 ℃.

For the test item an estimated partition coefficient of log Pow < - 2.25 was determined.  As the limit of the log Pow of the shake flask method is – 2, further dilution of the test item was not pursued.

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

16 January 2018 - 28 February 2018

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

unsuitable test system

Remarks:

Whilst the study has been conducted according to the guideline method under GLP conditions. The test item is a complex substance that has been determined to be surface active. As such this study must be regarded as not reliable. The nature of the test item means that there is the potential for secondary column interactions to occur, leading to a potential overestimation of the partition coefficient. To mitigate against this phenomenon, this study is being used as a part of a weight of evidence for this endpoint.

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - HPLC Method)

Version / remarks:

Regulation (EC) 440/2008 of 30 May 2008

Deviations:

yes

Remarks:

The study was conducted on a surface active substance.

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Version / remarks:

April 2004

Deviations:

yes

Remarks:

The study was conducted on a surface active substance.

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

other: N/A - Partition coefficient determined by HPLC method.

Key result

Type:

log Pow

Partition coefficient:

< 0

Temp.:

20 °C

Remarks on result:

other: Limit Value

Remarks:

Worst case limit.

Type:

log Pow

Partition coefficient:

< 0

Temp.:

20 °C

Remarks on result:

not determinable

Remarks:

Test 1 - Test item eluted from the column quicker than the unretained reference substance, i.e. tr < t0

Type:

log Pow

Partition coefficient:

< -1.31

Temp.:

20 °C

Remarks on result:

not determinable because of methodological limitations

Remarks:

Test 2 - The determined Log Pow value is below the determination limit of the method (Log Pow = 0.0 according to OECD 117 and EC method A.8).

Details on results:

Data Evaluation
Calculation of log k – The corresponding logarithms of the capacity factors, log k, were calculated from the retention times and the dead time.
Calibration Graph – A correlation graph of log k versus log Pow was plotted.
Sample Results – The log Pow was below the determination limit of this method (log Pow = 0.0), the log Pow was stated as < 0.

Table 3:          Retention time and log Pow of the test item (mean of two runs)

	Retention time [min]	Mean retention time [min]	Mean retention time of two runs [min]	Absolute deviation [min]	Log POWdetermined	Mean log POW	Mean log Powof two runs	Absolute deviation of log Pow
Run 1, Injection 1	1.536	1.54	1.63	0.16	Not determined.   tR< t0	< 0.0*	< 0.0*	N/A
Run 1, Injection 2	1.540
Run 1, Injection 3	1.545
Run 1, Injection 4	1.552
Run 2, Injection 1	1.706	1.71			-1.314	< 0.0*
Run 2, Injection 2	1.705				-1.319
Run 2, Injection 3	1.707				-1.308
Run 2, Injection 4	1.710				-1.292

*: below determination limit of the method (0.0 according to OECD 117 and EC method A.8). The log Pow values were below the limit of the method (log Pow < 0). Therefore the repeatability could not be determined.

 

Table 4:          Calibration parameter obtained from first run

	Slope	x	Intercept
Log Pow =	2.205795	log k	+ 1.278437
R =	0.9983

 

 

Table 5:          Calibration parameter obtained from second run

	Slope	x	Intercept
Log Pow =	2.205313	log k	+ 1.278914
R =	0.9983

 

 

Table 6:          Values for determination of Pow, dead time and calibration graph obtained from 1st run

Name	Log Pow nominal	RT [min]**	Mean RT [min]	SD [min]**	log k	Log Pow determined	Mean log Pow	SD log Pow
Test Item	---	1.536	1.543	0.007	N/A: tR< t0	< 0.0*	< 0.0*	N/A	Log k not determinable.
		1.540			N/A: tR< t0	< 0.0*
		1.545			N/A: tR< t0	< 0.0*
		1.552			N/A: tR< t0	< 0.0*
Thiourea**	---	1.626	1.627	0.001	---	---	---		Dead time
		1.626
		1.628
		1.626
2-Butanone	0.3	2.266	2.265	0.001	-0.406	0.38	0.38	0.00	Reference Items
		2.264			-0.407	0.38
		2.266			-0.406	0.38
		2.264			-0.407	0.38
Acetanilide	1.0	2.789	2.790	0.001	-0.146	0.96	0.96	0.00
		2.789			-0.146	0.96
		2.791			-0.145	0.96
		2.789			-0.146	0.96
Nitrobenzene	1.9	4.794	4.793	0.002	0.289	1.92	1.92	0.00
		4.791			0.289	1.92
		4.795			0.289	1.92
		4.792			0.289	1.92
Atrazine	2.6	7.193	7.187	0.005	0.534	2.46	2.46	0.00
		7.182			0.533	2.45
		7.185			0.534	2.46
		7.186			0.534	2.46
Diphenylamine	3.4	17.296	17.280	0.020	0.984	3.45	3.45	0.00
		17.262			0.983	3.45
		17.263			0.983	3.45
		17.299			0.984	3.45
Benzylbenzoate	4.0	30.792	30.757	0.031	1.253	4.04	4.04	0.00
		30.721			1.252	4.04
		30.745			1.253	4.04
		30.771			-0.406	0.38

*t_R< t₀: Retention time of the test item (t_R) below retention time of thiourea (t₀). Therefore Log Pow of the test item is below determination limit of the method (0.0 according to OECD 117 and EC method A.8)

**Thiourea was used for determination of the dead time; RT = retention time; SD = standard deviation

 

 

Table 7:          Values for determination of Pow, dead time and calibration graph obtained from 2nd run

Name	Log Pow nominal	RT [min]	Mean RT [min]	SD [min]	log k	Log Pow determined	Mean log Pow	SD log Pow
Test Item	---	1.706	1.707	0.002	-1.314	< 0.0*	< 0.0*	N/A
		1.705			-1.319	< 0.0*
		1.707			-1.308	< 0.0*
		1.710			-1.292	< 0.0*
Thiourea**	---	1.627	1.627	0.001	---	---	---	---	Dead time
		1.626
		1.627
		1.627
2-Butanone	0.3	2.265	2.265	0.001	-0.407	0.38	0.38	0.00	Reference Items
		2.266			-0.406	0.38
		2.264			-0.407	0.38
		2.265			-0.407	0.38
Acetanilide	1.0	2.789	2.789	0.002	-0.146	0.96	0.96	0.01
		2.791			-0.145	0.96
		2.787			-0.147	0.95
		2.788			-0.147	0.95
Nitrobenzene	1.9	4.795	4.794	0.003	0.289	1.92	1.92	0.00
		4.797			0.290	1.92
		4.790			0.289	1.92
		4.792			0.289	1.92
Atrazine	2.6	7.192	7.187	0.007	0.534	2.46	2.46	0.01
		7.192			0.534	2.46
		7.179			0.533	2.45
		7.183			0.533	2.45
Diphenylamine	3.4	17.294	17.280	0.021	0.984	3.45	3.45	0.00
		17.302			0.984	3.45
		17.259			0.983	3.45
		17.265			0.983	3.45
Benzylbenzoate	4.0	30.757	30.746	0.027	1.253	4.04	4.04	0.00
		30.771			1.253	4.04
		30.707			1.252	4.04
		30.747			1.253	4.04

*Log Pow of the test item is below determination limit of the method (0.0 according to OECD 117 and EC method A.8)

**Thiourea was used for determination of the dead time; RT = retention time; SD = standard deviation

Conclusions:

The test item was determined to have a partition coefficient (Log Pow) of < 0.0 at a mean temperature of 20 ± 1.0 °C.

Executive summary:

EU Method A.8.  – The partition coefficient of the test item was determined using the HPLC method.  The procedures employed were designed to be compatible with Method A.8., partition coefficient, of Commission Regulation (EC) No 440/2008 of 30 May 2008.

Analysis was performed using a solid phase of long hydrocarbon chains chemically bound onto silica (Luna 5µ C18(2) 100A; 250 x 3.0 mm), with a mobile phase mixture of 60 % methanol and 40 % ultra-pure water.  A PDA detector was used at 270 nm (reference solution), 223 nm (test item).  Reference items were used to determine column dead time and regression coefficients.

For the test item a measured partition coefficient of log Pow < 0.0 was determined.  The measured log Pow was below the limit of the method as the test item eluted from the column before the unretained organic substance selected to determine the deadtime of the column.  As the log Pow value of the test item is below the limit of detection for the method, repeatability could not be determined.

Description of key information

Partition coefficient: Log P_ow= < -2.25 at 20.0°C ± 1.0 °C; EU Method A.8. (Estimation Method (Solubility Ratio)); C Bär (2018)

Partition coefficient: Log P_ow= < 0.0 at 20.0°C ± 1.0 °C; EU Method A.8. (HPLC Method); C Bär (2018)

Key value for chemical safety assessment

Log Kow (Log Pow):

-2.25

at the temperature of:

19.8 °C

Additional information

EU Method A.8. – The partition coefficient of the test item was determined using the HPLC and calculation methods.  The procedures employed were designed to be compatible with Method A.8., partition coefficient, of Commission Regulation (EC) No 440/2008 of 30 May 2008.  As part of the wider testing programme it was determined experimentally that the test item is surface active (D. Anderson, EU Method A.5. (2018)).  As per EU Method A.8., neither the shake-flask method nor the HPLC method is applicable to surface active substances.  Potentially misleading results may arise due to emulsification (flask method) or secondary column interactions (HPLC Method).  As such the HPLC Method should be regarded as supplementary information as part of a weight of evidence based on the calculation method.

HPLC Method:  Analysis was performed using a solid phase of long hydrocarbon chains chemically bound onto silica (Luna 5µ C18(2) 100A; 250 x 3.0 mm), with a mobile phase mixture of 60 % methanol and 40 % ultra-pure water.  A PDA detector was used at 270 nm (reference solution), 223 nm (test item).  Reference items were used to determine column dead time and regression coefficients.

For the test item a measured partition coefficient of log Pow < 0.0 was determined.  The measured log Pow was below the limit of the method as the test item eluted from the column before the unretained organic substance selected to determine the dead time of the column.  As the log Pow value of the test item is below the limit of detection for the method, repeatability could not be determined.

Estimation Method (Solubility Ratio):  An aliquot of test item was placed in a glass vessel, n-octanol was added in a stepwise manner.  After each addition of n-octanol, the vessel was shaken for at least 10 min.  The sample was then visually checked for undissolved test item.  If the test item was not dissolved further n-octanol was added in the manner previously described.  The test was performed at 19.8 ℃.

For the test item an estimated partition coefficient of log Pow < - 2.25 was determined.  As the limit of the log Pow of the shake flask method is – 2, further dilution of the test item was not pursued.