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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From 4 October 2012 to 25 January 2013
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:
2012-12-15
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
2.1
Temp.:
25 °C
pH:
>= 7.6 - <= 7.85
Remarks on result:
other: log Pow of the C12 fraction (weighted average value)

Results:

Calibration curve for 1 -octanol phases analysis

Reference of calibration solution Peak area (area units) Conc (mg/L) Response factor Final Volume (ml) Dilution factor  Sample weight (mg) Conc back-calc Diff
A C= (w*P)/(V*Df) RF = A/C V Df w C'= (A-b)/a %
Lin 25% 1830264 19.31 9.48048E+04 100 4.0 20.11 18.49 -4.25%
Lin 25% 1845749 19.31 9.56069E+04 100 4.0 20.11 18.65 -3.37%
Lin 50% 3905839 39.71 9.83700E+04 100 1.0 10.34 40.46 1.89%
Lin 50% 3915468 39.71 9.86125E+04 100 1.0 10.34 40.56 2.14%
Lin 75% 5574447 57.14 9.75591E+04 100 1.0 14.88 58.12 1.72%
Lin 75% 5493480 57.14 9.61421E+04 100 1.0 14.88 57.26 0.21%
REF05 7463735 78.84 9.46752E+04 100 1.0 20.53 78.11 -0.91%
REF05 7502554 78.84 9.51676E+04 100 1.0 20.53 78.52 -0.39%
Lin 125% 9176261 96.38 9.52052E+04 100 1.0 25.10 96.24 -0.16%
Lin 125% 9169449 96.38 9.51346E+04 100 1.0 25.10 96.16 -0.23%
Lin 150% 10797715 112.59 9.59040E+04 100 1.0 29.32 113.40 0.72%
Lin 150% 10661311 112.59 9.46925E+04 100 1.0 29.32 111.95 -0.57%

Response function Peak Area = 94488.13*Concentration + 83143.53

The graph of the calibration curve is shown in Attachment 1.

Calibration curve for water phase analysis:

Reference of calibration solution Peak area (area units) Conc (mg/L) Response factor Final Volume (ml) Dilution factor  Sample weight (mg) Conc back-calc Diff
A C= (w*P)/(V*Df) RF = A/C V Df w C'= (A-b)/a %
REF 05 dil20 369203 3.94 9.36645E+04 100 20 20.53 3.90 -1.01%
REF 05 dil20 351222 3.94 8.91028E+04 100 20 20.53 3.69 -6.34%
REF 05 dil10 699817 7.88 8.87696E+04 100 10 20.53 7.74 -1.78%
REF 05 dil10 710573 7.88 9.01340E+04 100 10 20.53 7.86 -0.25%
REF 05 dil5 1413337 15.77 8.96387E+04 100 5 20.53 16.03 1.65%
REF 05 dil5 1437975 15.77 9.12013E+04 100 5 20.53 16.32 3.49%
REF 05 dil4 1720595 19.71 8.73009E+04 100 4 20.53 19.60 -0.56%
REF 05 dil4 1733152 19.71 8.79380E+04 100 4 20.53 19.75 0.20%
REF 05 dil2,5 2735643 31.53 8.67520E+04 100 2.5 20.53 31.40 -0.44%
REF 05 dil2,5 2734947 31.53 8.67299E+04 100 2.5 20.53 31.39 -0.48%

Response function Peak Area = 86061.61*Concentration + 33709.60

The graph of the calibration curve is shown in Attachment 1.

Main test results:

The three filtered aliquots of 50 mL obtained from the 1-octanol saturated phase were analyzed and the concentrations of the C12 fraction were found to be equal to 1.86 g/L (4.84 g/L of test item). This value is lower than the theoretical one and shows a weak dissolution of test item during the two hours of preparation.

The results for the C12 fraction concentration in the two phases at each time are given in the following table:

Vessel number and sampling time Concentration in the aqueous phase (mg/l) Concentration in the 1-octanol phase (mg/l) Pow ratio log Pow
12-091 Z1T=93H 12.70 1499 118.00 2.07
12-091 Z2T=93H 11.44 1524 133.20 2.12
12-091 Z3T=93H 12.14 1558 128.30 2.11
12-091 Z1T=117H 11.24 1497 133.20 2.12
12-091 Z2T=117H 11.94 1539 128.90 2.11
12-091 Z3T=117H 11.78 1582 134.30 2.13
12-091 Z1T=137H 11.54 1503 130.20 2.11
12-091 Z2T=137H 12.18 1601 131.40 2.12
12-091 Z3T=137H 13.38 1629 121.70 2.09
12-091 Z1T=144H 11.48 1511 131.60 2.12
12-091 Z2T=144H 12.78 1513 118.40 2.07
12-091 Z3T=144H 13.26 1569 118.30 2.07
12-091 Z1T=163H 12.02 1489 123.90 2.09
12-091 Z2T=163H 12.14 1552 127.80 2.11
12-091 Z3T=163H 12.34 1599 129.60 2.11

The pH of the saturated water phase at the start of the test was 7.88 at 21 °C.The measured pH of the aqueous phases were between 7.60 and 7.85 at 21 °C.

The average value of log Pow of the different vessel units is calculated as the average of the results of the individual experimental units weighed with their respective variances.The results are shown in the following table.

Vessel Z1 Mean value Z1 Standard deviation Z1 Vessel Z2 Mean value Z2 Standard deviation Z2 Vessel Z3 Mean value Z3 Standard deviation Z3
2,07 2,102 0,02 2,12 2,106 0,02 2,11 2,102 0,02
2,12 2,11 2,13
2,11 2,12 2,09
2,12 2,07 2,07
2,09 2,11 2,11

Mean / Vessel Average Standard deviation
Vessel Z1 2,102 2,103 0,02
Vessel Z2 2,106
Vessel Z3 2,102

Using the low stirring method, it was shown that the weighed average value of the 1-octanol/water partition coefficient log10 Pow of the C12 fraction present in test item is equal to 2.10 ± 0.02 at 25 ± .1°C.

Demonstration of attainment of equilibrium:

Achievement of chemical equilibrium is demonstrated by plotting for each vessel unit log Pow against time as shown in the figures shown in Attachment 2 where the slopes are very near to 0.

Conclusions:
Using the low stirring method, it was shown that the weighed average value of the 1-octanol/water partition coefficient log10 Pow of the C12 fraction present in test item is equal to 2.10 ± 0.02 at 25 ± 1°C.
Executive summary:

The n-octanol/water partition coefficient of the test item (= substance EC 939-455-3) was investigated in a GLP-compliant study performed in accordance with OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method). The mean n-octanol/water partition coefficient log10 Pow of the C12 fraction present in test item was 2.10 ± 0.02 at 25°C.

Endpoint:
partition coefficient
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
1. HYPOTHESIS FOR THE ANALOGUE APPROACH
C8-C18 AAPHS and C12-18 AAPHS have the same functional groups, and general composition. The main variable resides in the alkyl chain distribution.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Source chemical = C8-18 cocamidopropyl hydroxysultaine (EC 939-455-3).
Target chemical = C12-18 cocamidopropyl hydroxysultaine (EC 939-457-4).

3. ANALOGUE APPROACH JUSTIFICATION
The alkyl C-chain distribution of the source chemical significantly overlaps with the one of the target chemical, the C12-alkyl derivative being the major constituent in both chemicals. The structural differences in side C-chains is not expected to lead to significant differences on phys-chem properties.

4. DATA MATRIX
See "Documentation and scientific justification of the read-across approach" in section 13.2.
Reason / purpose:
read-across source
Key result
Type:
log Pow
Partition coefficient:
2.1
Temp.:
25 °C
pH:
>= 7.6 - <= 7.85
Remarks on result:
other: log Pow of the C12 fraction (weighted average value)
Remarks:
read-across from EC 939-455-3
Conclusions:
By analogy with the source substance EC 939-455-3, a n-octanol/water partition coefficient log10 Pow of 2.10 ± 0.02 at 25°C was reported for the target substance 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18(even numbered) acyl) derivs., hydroxides, inner salts (EC 939-457-4).

Description of key information

As the n-octanol/water partition coefficient of the substance EC 939-457-4 has not been determined experimentally, a read-across approach was followed to fill in the endpoint. The n-octanol/water partition coefficient of a structural analogue substance (= source substance EC 939-455-3) was investigated in a GLP-compliant study (Meriaux, 2013) performed in accordance with OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method). The mean n-octanol/water partition coefficient log10 Pow of the analogue substance was 2.10 ± 0.02 at 25°C. By analogy, a n-octanol/water partition coefficient log10 Pow of 2.10 ± 0.02 at 25°C was reported for the target substance 1-Propanaminium, N-(3-aminopropyl)-2-hydroxy-N,N-dimethyl-3-sulfo-, N-(C12-18(even numbered) acyl) derivs., hydroxides, inner salts (EC 939-457-4).

The alkyl C-chain distribution of the source substance EC 939-455-3 significantly overlaps with the one of the target substance EC 939-457-7, the C12-alkyl derivative being the major constituent in both chemicals. The structural differences in side C-chains is not expected to lead to significant differences on phys-chem properties.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.1
at the temperature of:
25 °C

Additional information

The n-octanol/water partition coefficient of the structural analogue substance (= source substance EC 939-455-3) was investigated in a GLP-compliant study (Meriaux, 2013) performed in accordance with standard methods, without deviations. The study is considered as reliable (Klimisch 1) and was selected as key study for the endpoint of the target substance EC 939-457-4.