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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
From Oct. 13, 2011 to Nov. 28, 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
(according to OECD and EU principles of GLP)
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
photometric method
Key result
Type:
log Pow
Partition coefficient:
1.51
Temp.:
25 °C
pH:
6
Remarks on result:
other: Mean of 3 runs
Details on results:
The Log Pow was estimated to be -0.48 in the preliminary estimation. In the main study, Log Pow was 1.644, 1.448 and 1.429 for run 1, 2 and 3 respectively. Details are provided in the “table 1” under “Any other information on results incl. tables

Table 1: Log Pow results (study# 85858)

Sampling point  Average g/L aqueous phase  Average g/L octanol phase  Log Pow 
Run 1 
1 0.131 4.198 1.505
2 0.122 6.49 1.726
3 0.122 4.886 1.602
4 0.113 5.803 1.711
5 0.113 5.344 1.675
Average  1.644
Variance  0.00829
Log Pow weighted with respective variance  1.644
Run 2
1 0.108 2.871 1.424
2 0.105 2.871 1.435
3 0.1 3.054 1.485
4 0.105 2.963 1.449
Average  1.448
Variance  0.00071
Log Pow weighted with respective variance  1.448
Run 3
1 0.108 2.963 1.438
2 0.103 2.871 1.447
3 0.103 2.688 1.418
4 0.1 2.596 1.415
Average  1.429
Variance  0.00024
Log Pow weighted with respective variance  1.429

The test substance is a mixture of isomeric compounds which may undergo ionisation in solution. The result reported is based on the prevalent C12 isomer. As a result, when interpreting the partition coefficient result, the pH; the composition of the sample; the chain length of the individual constituents; as well as homogeneity of the mixture must be considered. Where all these factors are considered, MEA-LAS would be expected to have a Log P range.

Conclusions:
The partition coefficient (n-octanol/water), log Pow, of MEA-LAS was determined as 1.51 (mean of 3 runs) by employing the slow-stirring method (OECD Guideline 123).
Executive summary:

The partition coefficient (n-octanol/water), log Pow, of MEA-LAS was determined following OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method).

Three slow-stir experiments were run. In Flask 1, 765 mL of water and 45 mL of octanol were added to the flask. After the two day equilibration, the octanol was removed. 0.349 g of sample was dissolved into it, and then added back to the test vessel. In Flask 2, 680 mL of water and 40 mL octanol were added to the     flask. After the two day equilibration, the octanol was removed. 0.200 g of sample was dissolved into it, and then added back to the test vessel. In Flask 3, 850 mL of water and 50 mL octanol were added to the flask. After the two day equilibration, the octanol was removed. 0.203 g of sample was dissolved into it, and then added back to the test vessel.

All flasks were left for 24 h before samples were taken. Each set of samples were taken at least 5 h apart, generally morning and evening. UV spectrophotometer was used for the analysis.

The partition coefficient (n-octanol/water), log Pow, of MEA-LAS was determined as1.51 (mean of run 1, 2 and 3 having values 1.644, 1.448 and 1.429) by employing the slow-stirring method.

This partition coefficient (n-octanol/water) test is classified as acceptable, and satisfies the guideline requirements of the OECD Guideline 123.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From Sept. 25, 2018 to Feb. 27, 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
(OECD Principles of GLP)
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
other: LC-MS/MS system
Key result
Type:
log Pow
Partition coefficient:
3.84
pH:
2
Remarks on result:
other: Mean value
Key result
Type:
Pow
Partition coefficient:
6 876
pH:
2
Remarks on result:
other: Mean value
Key result
Type:
log Pow
Partition coefficient:
2.51
pH:
7
Remarks on result:
other: Mean value
Key result
Type:
Pow
Partition coefficient:
321
pH:
7
Remarks on result:
other: Mean value
Key result
Type:
log Pow
Partition coefficient:
2.2
pH:
9
Remarks on result:
other: Mean value
Key result
Type:
Pow
Partition coefficient:
158
pH:
9
Remarks on result:
other: Mean value
Details on results:
The logP was calculated by a multi-step calculation:
1. The mean values of all concentrations of the triplicates in octanol were calculated for each pH value and for each day.
2. The mean values of all concentrations of the triplicates in water were calculated for each pH value and each dilution ratio (for all values inside the calibration range and >LOQ) and for each day.
3. The concentration of HLAS in octanol was divided by the concentration of HLAS in water and the negative decimal logarithm of this value was calculated.
4. A mean of all logP values of the consecutive days was calculated by calculating mean P value and negative decimal logarithm of this value.

This calculation procedure was performed for the entire UVCB substance as well as the single homologues (named C10, C11, C12 and C13 hereafter).

Details regarding results are provided in “Any other information on results incl. tables” section.

Calibration:

- Calibration was carried out in a range of 0.02 to 2 μg/vial (1 mL aqueous/ buffer phase and 0.25 mL organic ACN phase). The calibration spike solutions were prepared in ACN ranging from 0.1 to 10 mg/ L. The sum of all peak areas (see chromatograms) was plotted against the nominal concentration for calibration.

- Calibration for validation in octanol:

  Response = -24899.4x2 + 363702x-143.566

  Correlation coefficient: r2= 0.999925

Regression quality: As the calculated correlation coefficient (r2) for the test item was close to 1 the quadratic calibration function with 1/x weighting was accepted.

- Calibration for evaluation of the samples from pH 2:

  Response = -15172.8x2+ 288331x + 93.4952

  Correlation coefficient: r2= 0.999663

  Regression quality: As the calculated correlation coefficient (r2) for the test item was close to 1 the quadratic calibration function with 1/x weighting was accepted.

Validation:

The analytical methods for the test item have been successfully validated and results met the validation criteria as given in the SANCO 3029 guideline.

a) Validation results of the method to determine HLAS in octanol and aqueous buffer solution:

- Accuracy (recovery) in octanol and aqueous buffer system: The mean recoveries and the overall mean recovery values are in the defined range (recovery 70 – 110% with an RSD < 20%) of SANCO/3029/99 rev.4 (11/07/00). The accuracy of the method is therefore accepted.

- Repeatability (precision):

a) Octanol: The mean RSDs of 10.1% and 1.65% for LOQ and 10x LOQ as well as the overall mean RSD of 7.69% prove the repeatability of the analytical method for the determination analyte in aqueous solution.

b) Aqueous buffer solution: The mean RSDs of 1.79% and 1.25% for LOQ and 10x LOQ as well as the overall mean RSD of 1.41% prove the repeatability of the analytical method for the determination analyte in aqueous solution.

- Specificity and blanks in octanol and aqueous buffer solution: The LC-MS system able to determine the test item in the processed injection solutions without interference of matrix compounds above 30% of the LOQ. Since there were no peaks higher than 30% of the LOQ at the retention time of the analyte the method is accepted as specific.

Table 6: Validation results of the method to determine HLAS in octanol (Study# 98971)

Sample Level [µg/vial] Level [g/L]* Conc. [µg/vial] Conc. [g/L] Rec. [%] Mean Rec. [%] SD [%] Rec. RSD [%]
Blank 1 0       n.a. n.a. n.a. n.a.
Blank 2 0       n.a.
LOQ 1 0.10 0.10 0.088 0.088 88.0 90.4 9.13 10.1
LOQ 2 0.100 0.100 100
LOQ 3 0.076 0.076 76.0
LOQ 4 0.093 0.093 93.0
LOQ 5 0.095 0.095 95.0
10 x LOQ 1 1 1 0.96 0.959 95.9 97.5 1.61 1.65
10 x LOQ 2 0.96 0.957 95.7
10 x LOQ 3 0.99 0.985 98.5
10 x LOQ 4 0.99 0.993 99.3
10 x LOQ 5 0.98 0.981 98.1
Overall values 94 7.22 7.69

* This value is calculated by multiplying *(1.25(volume vial)/0.25 (volume ACN phase) *200 (dilution factor Octanol in ACN)/1000 (from mg to g)).

Table7: Validation of the method to determine HLAS in aqueous buffer solution (Study# 98971)

Sample Level [µg/vial] Level [mg/L] Conc. [µg/vial] Conc. [mg/L] Rec. [%] Mean Rec. [%] SD [%] Rec. RSD [%]
Blank 1 0     0 n.a. n.a. n.a. n.a.
Blank 2 0     0 n.a.
LOQ 1 0.05 0.0625 0.053 0.0663 106 103 1.79 1.73
LOQ 2 0.051 0.0638 102
LOQ 3 0.051 0.0638 102
LOQ 4 0.051 0.0638 102
LOQ 5 0.052 0.065 104
10 x LOQ 1 0.50 0.625 0.513 0.641 102.6 103 1.25 1.21
10 x LOQ 2 0.508 0.635 101.6
10 x LOQ 3 0.522 0.653 104.4
10 x LOQ 4 0.522 0.653 104.4
10 x LOQ 5 0.520 0.650 104
Overall values 103 1.46 1.41

Table 8: Results concentration in the different phases and individual day result of log Pow at pH 2, 7 and 9 (Study# 98971)

pHwater Sampling time [days] C1-octanol[mg/L] Cwater[mg/L] RSD C1-octanol[%] RSD Cwater[%] Pow log Pow RSD Pow [%] RSD log Pow [%]
2 1 956 0.135 1.16 14.18 7060 3.85 10.24 1.21
2 947 0.130 7285 3.86
3 957 0.143 6713 3.83
4 973 0.169 5750 3.76
5 972 0.128 7574 3.88
7 1 949 2.86 1.85 3.89 332 2.52 2.65 0.46
2 930 3.01 309 2.49
3 922 2.84 325 2.51
4 901 2.80 322 2.51
5 926 2.92 317 2.50
9 1 865 5.00 2.87 2.32 173 2.24 5.8 1.11
2 844 5.55 152 2.18
3 855 5.40 158 2.20
4 803 5.30 151 2.18
5 833 5.45 153 2.18

Table 9: Summary of mean log Pow values for HLAS at different pH values (Study# 98971)

pH RSD Pow (%) RSD log Pow (%) Mean Pow Mean log Pow
2 10.24 1.21 6876 3.84
7 2.65 0.46 321 2.51
9 5.8 1.11 158 2.2

Results for single homologues

A percentage of all individual homologues was calculated under the assumption that the response factor is the same for all mass transitions. For calculation, percentage of the single homologues in the test item the single peak areas at each calibration level were compared to the sum of all single peak areas and the mean value of the percentage reported.

For the logP calculation of the single homologues, a calibration using the single peaks was plotted against the nominal concentration in calibration samples (taking into account the percentage of the single homologues) and concentration in the samples single peaks were determined by integrating in the same way as for the calibration samples and followed by calculation with software.

Table 10: Summary of percentage of individual homologues along with their respective log Pow at different pH (Study# 98971)

Homologue (%) pH Mean log Pow RSD log Pow [%]
C10(9.8%) 2 3.12 1.28
7 1.8 0.65
9 1.46 2.06
C11(32.9%) 2 3.76 1.19
7 2.42 0.57
9 2.11 1.11
  C12(32.9%) 2 4.4 1.33
7 3.04 0.83
9 2.72 1.01
  C13(24.4%) 2 5.07 1.32
7 3.67 1.1
9 3.37 0.64

Table 11: Results concentration for homologues in the different phases and individual day result of log Pow at pH 2, 7 and 9 (Study# 98971)

pHwater Homologue Sampling time [days] C1-octanol[mg/L] Cwater[mg/L] RSD C1-octanol[%] RSD Cwater[%] Pow log Pow RSD Pow [%] RSD log Pow [%]
2 C10 1 90.2 0.07 0.59 12.03 1329 3.12 9.04 1.28
2 89.7 0.06 1468 3.17
3 88.9 0.07 1276 3.11
4 90.1 0.08 1164 3.07
5 89.6 0.06 1422 3.15
C11 1 307.3 0.052 1.24 13.89 5857 3.77 9.98 1.19
2 304.9 0.049 6205 3.79
3 307.3 0.054 5669 3.75
4 314.3 0.064 4926 3.69
5 311.8 0.048 6433 3.81
C12 1 307.8* 0.012 2.56 17.25 26545 4.42 12.70 1.33
2 310.8* 0.012 25383 4.40
3 318.6* 0.013 24785 4.39
4 325.5* 0.016 19885 4.30
5 325.2* 0.011 28400 4.45
C13 1 247.9# 0.0020 1.86 23.77 126617 5.10 13.87 1.32
2 252.2# 0.0021 122619 5.09
3 247.8# 0.0019 129225 5.11
4 257.0# 0.0029 89389 4.95
5 257.4# 0.0021 124380 5.09
7 C10 1 86.1 1.31 1.15 0.46 66 1.82 2.71 0.65
2 85.2 1.35 63 1.80
3 84.9 1.35 63 1.80
4 83.4 1.34 62 1.79
5 84.7 1.39 61 1.79
C11 1 303.6 1.11 1.78 4.65 273 2.44 3.16 0.57
2 299.0 1.19 252 2.40
3 295.1 1.11 267 2.43
4 289.3 1.09 266 2.42
5 296.2 1.15 258 2.41
C12 1 317.8 0.28 2.82 8.62 1128 3.05 5.60 0.83
2 304.2 0.31 981 2.99
3 302.3 0.27 1129 3.05
4 293.9 0.27 1095 3.04
5 304.0 0.28 1089 3.04
C13 1 252.2 0.052 3.55 13.87 4820 3.68 8.97 1.10
2 240.9 0.060 4037 3.61
3 238.3 0.046 5171 3.71
4 228.3 0.049 4637 3.67
5 240.4 0.049 4886 3.69
9 C10 1 77.7 2.47 2.79 5.15 32 1.50 6.88 2.06
2 75.0 2.51 30 1.48
3 76.3 2.75 28 1.44
4 72.0 2.73 26 1.42
5 75.6 2.54 30 1.47
C11 1 276.3 1.95 2.76 3.31 142 2.15 5.51 1.11
2 269.9 2.19 123 2.09
3 273.1 2.09 130 2.12
4 257.1 2.05 125 2.10
5 266.1 2.09 127 2.11
C12 1 288.6 0.51 3.01 6.41 569 2.76 6.35 1.01
2 282.3 0.59 479 2.68
3 286.8 0.54 533 2.73
4 269.3 0.52 514 2.71
5 273.4 0.54 509 2.71
C13 1 231.3 0.096 3.64 5.37 2411 3.38 4.93 0.64
2 225.3 0.103 2180 3.34
3 223.2 0.095 2354 3.37
4 210.8 0.094 2239 3.35
5 215.8 0.088 2451 3.39

* All values for concentration of the C12-homologue in pH 2 buffer are <LOQ but within the calibration range. Values for concentration and logP are thus semi-quantitative.

# All values for concentration of the C13-homologue in pH 2 buffer are <LOQ and not within the calibration range. Values for concentration and logP thus might have a bigger error.

Conclusions:
The Partition Coefficient (n-octanol/water), log Pow, of HLAS was determined as 3.84, 2.51 and 2.20 at pH 2, 7 and 9, respectively by employing slow-stirring method (OECD Guideline 123).
Executive summary:

The Partition Coefficient (n-octanol/water), log Pow, of HLAS was determined following OECD Guideline 123 [Partition Coefficient (1-Octanol / Water), slow-stirring method].

The tests were carried out in triplicates. For each pH value, three 250 mL bottles were placed on stirrers in a climate cabinet (at 25±0.5°C) and 180 mL of the respective buffer solution were added to the vessels followed by gentle addition of 40 mL of octanol for avoiding turbulences. After addition of respective buffer and octanol solution, samples were stirred at a 100 rpm setup over a day and two nights for achieving saturation of the two phases. After saturation, stirring was stopped for ca. 1-hr and 50 mL of test substance in solvent (ca. 90 g HLAS/50 mL octanol) were added gently. Samples were again stirred overnight followed by collection of sample on each day for consecutive five days. Samples were collected via drain-port of vessel for the aqueous (buffer) phase while octanolic samples were collected using a Pasteur pipette from top of vessel. LC-MS/MS system was used for analysis and validated according to the OECD SANCO 3029/99 rev. 4 guideline.

The Partition Coefficient (n-octanol/water), log Pow, of HLAS were determined as 3.84, 2.51 and 2.20 at pH 2, 7 and 9, respectively by employing slow-stirring method.

This Partition Coefficient (n-octanol/water) test is classified as acceptable, and satisfies the guideline requirements of the OECD Guideline 123.

Endpoint:
partition coefficient
Type of information:
calculation (if not (Q)SAR)
Remarks:
(estimated by calculation)
Adequacy of study:
supporting study
Study period:
12/1/2011 to 12/8/2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Calculated by ACD/Labs software. Calculated Log P (or Log D) for surfactants is uncertain as experimental values in training set can vary by test method; surfactants tend to concentrate at interfaces rather than partition between octanol and water
Principles of method if other than guideline:
Calculation by QSAR; ACD/Labs software. Linear fragmental QSAR model. LogKow is calculated using the principle of isolating carbons. Well-characterized logKow contributions have been compiled for atoms, structural fragments, and intramolecular interactions. A secondary algorithm is applied when unknown fragments are present.
GLP compliance:
not specified
Type of method:
other: QSAR
Partition coefficient type:
octanol-water
Key result
Partition coefficient:
1.7
Temp.:
20 °C
pH:
>= 5 - <= 9
Remarks on result:
other: log D. Weighted average of C10, C11, C12, C13 alkyl chain lengths comprising HLAS
Details on results:
Log D (distribution coefficient) is more appropriate than log P (partition coefficient), because HLAS is essentially 100% ionized (anionic) at environmentally relevant pH's (pH 5-9). The pKa for HLAS is -0.45 (estimated by ACD/Labs). The calculated log P is based on the protonated (neutral, not ionized) form of LAS, and therefore greatly overestimates log P.

Table1: QSAR Calculations of Partition Coefficient of HLAS (Benzenesulfonic acid, 4-C10-13-sec-alkyl derivs.; CAS RN 85536-14-7)

Alkyl chain length of the LAS Log P v 12.0 (ACD/Labs) Log P (EpiSuites) Log D (ACD/Labs) v 12.0
10 4.42 3.73 0.92
11 4.93 4.22 1.43
12 5.44 4.71 1.94
13 5.95 5.2 2.45
C10-C13 (weighted average) ** 5.24 4.51 1.73

 ** See Table below for example calculation.

Table 2: Log D estimates based on the latest ACD Labs Percepta 2014 version

Alkyl chain length of the LAS

Log D at pH= 6

Log D at pH= 7

Log D at pH= 7.4

Log D at pH= 8

Log D at pH= 9

10

-0.36

-0.36

-0.36

-0.36

-0.36

11

0.43

0.43

0.43

0.43

0.43

12

0.69

0.69

0.69

0.69

0.69

13

1.65

1.65

1.65

1.65

1.65

Table 3: Log D of HLAS, Weighted Average Based on Typical Alkyl Chain Length Composition

Alkyl chain length of LAS Log D % in HLAS (log D) x (%) Log D of C10-C13 HLAS
10 0.92 13 0.12  
11 1.43 36 0.51  
12 1.94 31 0.6  
13 2.45 20 0.49  
C10-C13       1.73 

HLAS= Benzenesulfonic acid, 4-C10-13-sec-alkyl derivs.; CAS RN 85536-14-7

Log D calculatedby ACD/Labs software.

Table 4: Log D of HLAS,Weighted Average Based on Typical Alkyl Chain Length Composition

Alkyl chain length of LAS Log D at pH=7 (ACD Labs Percepta 2014 version) % in HLAS (log D) x (%) Log D of C10-C13 HLAS
10 -0.36 13 -0.05  
11 0.43 36 0.15  
12 0.69 31 0.21  
13 1.65 20 0.33  
C10-C13       0.62
Conclusions:
The log Kow (log D) of HLAS was 1.73, calculated by QSAR (ACD/Labs).
Executive summary:

The log Kow of HLAS (Benzenesulfonic acid, 4-C10-13-sec-alkyl derivs.; CAS RN 85536-14-7 was calculated by QSAR, using the ACD/Labs software. The HLAS is comprised of C10, C11, C12, and C13 alkyl chain lengths. Because HLAS is dissociated at environmentally relevant pH's, log D (distribution coefficient) is more appropriate, and log D was used instead of log P (partition coefficient). The pKa of HLAS is -0.45.

Using the ACD/Labs QSAR software, the log D was calculated for the C10, C11, C12, and C13 alkyl chain lengths separately. The log D of each of these homologs was as follows:

C10      0.92

C11      1.43

C12      1.94

C13      2.45

Then, a weighted average log D was calculated, based on the amount of each alkyl chain length in HLAS.

The weighted average log D of HLAS was 1.73.

Description of key information

Partition coefficient (log Kow) values were determined for MEA-LAS (CAS No. 85480 -55 -3) (OECD Guideline 123, Slow Stir Method) and the closely related HLAS (CAS No. 85536 -14 -7) (OECD Guideline 123, Slow Stir Method, and (Q)SAR modeling using ACDLabs software). The conservative result obtained from the slow stir method testing with HLAS, i.e. the log Kow of 2.51 at pH 7, is retained as key value.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.51

Additional information