Reaction products of 2-hydroxyethyl methacrylate and diphosphorous pentoxide and water

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Justification for type of information:

1. SOFTWARE
Estimation Programme Interface (EPI) Suite programme for Microsoft Windows v4.11
Contact EPISuite:
U.S. Environmental Protection Agency
1200 Pennsylvania Ave.
N.W. (Mail Code 7406M)
Washington, DC 20460

2. MODEL (incl. version number)
KOWWIN v1.68
September 2010 (model development); November 2012 (model publication)

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See QPRF attached: ‘QPRF Title: Substance: Reaction products of 2-hydroxyethyl methacrylate and diphosphorous pentoxide and water using the model KOWWIN v1.68 for the endpoint: Partition Coefficient (Log Kow)’ version 1.0; 30 May 2018.

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
Full details of the method are provided in the attached QMRF named ‘QMRF Title: KOWWIN v1.68 : n-Octanol/Water Partition Coefficient (Log Kow)’ version 1.03; date: 01 September 2015; updated 30 May 2018.

5. APPLICABILITY DOMAIN
See ‘any other information on results incl. tables’.
See attached QPRF attached: ‘QPRF Title: Substance: Reaction products of 2-hydroxyethyl methacrylate and diphosphorous pentoxide and water using the model KOWWIN v1.68 for the endpoint: Partition Coefficient (Log Kow)’ version 1.0; 30 May 2018.

6. ADEQUACY OF THE RESULT
1) QSAR model is scientifically valid. 2) The substance falls within the applicability domain of the QSAR model. 3) The results are adequate when taken under consideration of REACH Regulation (EC) 1907/2006 in a weight of evidence.

Guideline:

other: REACH Guidance on QSARs R.6, May/July 2008

Principles of method if other than guideline:

- The model and the training and validation sets are published by US Environmental Protection Agency (USA).
The experimental Log Kow values in the training set and validation set were measured using one or more methods equivalent or similar to the following guidelines:
- Shake Flask method (OECD TG 107)
- HPLC method (OECD TG 117)
- Slow Stirring method (OECD TG 123)
Plus relevant EU (1992 as amended) and US EPA OPPTS (1982 as amended) and ASTM (1993) methods may be also used where appropriate.
A full list of experimental Log Kow reference citations is provided in the KOWWIN help menu with additional reference citations.
- Justification of QSAR prediction: The result should be considered in relation to corresponding information presented and in accordance with the tonnage driven information requirements of REACH Regulation (EC) 1907/2006 in a weight of evidence.
Provision of measured experimental Log Kow has been determined as not technically possible under guideline OECD TG 117 HPLC method due to constituents outside of the domain of the test. It is also potentially not technically possible by other methods such as OECD TG 107 flask method and OECD TG 123 slow stir method, given the wide range of partitioning constituents and/or complex nature of the substance which is an: Unknown or Variable composition, Complex reaction products or Biological Materials (UVCB) substance.
Therefore, in accordance with the tonnage driven information requirements: the calculated method for Log Kow has been adopted. There is evidence the substance may be presented in representative blocks under the ‘block method’ of environmental risk assessment, given their comparable chemistries and physico-chemical properties. Specifically, the substance consists of blocks of constituents of Log Kow < 4.0.

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

Detailed information on the 'test material identity' is provided in the attached QSAR Prediction Reporting Format (QPRF) document including information on individual constituents.

Type:

log Pow

Partition coefficient:

>= -1.718 - <= 2.2

Temp.:

25 °C

pH:

ca. 7

Remarks on result:

other: Value represents the range of predicted Log P for all constituents; no constituents have predictions of Log P > 4.0 cut-off value

1. Defined Endpoint:

QMRF 1. Physical Chemical Properties

QMRF 1.6. Octanol-water partition coefficient (Kow)

Reference to type of model used and description of results:

KOWWIN v1.68; integrated within the Estimation Programme Interface (EPI) Suite programme for Microsoft Windows v4.11; September 2010 (model development); November 2012 (model publication)

 

2. Description of results and assessment of reliability of the prediction:

The predicted values are provided within the QPRF attached: ‘QPRF Title: Substance: Reaction products of 2-hydroxyethyl methacrylate and diphosphorous pentoxide and water using the model KOWWIN v1.68 for the endpoint: Partition Coefficient (Log Kow)’ version 1.0; 30 May 2018.

 

The range of constituents was: Log Kow = -1.7179 to 2.1995 in three blocks, respectively.

The majority of constituents had Log Kow = -0.7490 to 1.0627 and no constituents have predictions for Log Kow > 4.0.

Table 1.0 – Range of constituents

Constituent Number	Constituent Name (IUPAC)	Molecular Weight	Log Kow (KOWWIN)	Below Log Kow = 4.0 cut-off (yes/no)
1	phosphoric acid	97.9952	-0.7699	YES
2	2-(dimethylphosphoryl)ethyl 2-methylbutanoate	206.222	0.6535	YES
3	2-hydroxyethyl methacrylate	130.1418	0.3014   Experimental: 0.47 Hansch, (1995)	YES
4	2-hydroxyethyl 2-hydroxy-2-methylpropanoate	148.158	-0.7879	YES
5	{2-[(2-methylprop-2-enoyl)oxy]ethoxy}phosphonic acid	210.1217	0.2199	YES
6	bis({1-[(2-methylprop-2-enoyl)oxy]ethoxy})phosphinic acid	322.2482	1.0627	YES
7	2-{[bis({2-[(2-methylprop-2-enoyl)oxy]ethoxy})phosphoryl]oxy}ethyl 2-methylprop-2-enoate	434.378	2.1995	YES
8	{[hydroxy({2-[(2-methylprop-2-enoyl)oxy]ethoxy})phosphoryl]oxy}phosphonic acid	290.101	-0.7490	YES
9	{[hydroxy({[hydroxy({2-[(2-methylprop-2-enoyl)oxy]ethoxy})phosphoryl]oxy})phosphoryl]oxy}phosphonic acid	370.079	-1.7179	YES

 

It is noted by the applicant there is no universally acknowledged applicability domain for the model. However, assessment of the substance within the applicability domains recommended by the developers is documented within the corresponding QMRF named ‘QMRF Title: KOWWIN v1.68 : n-Octanol/Water Partition Coefficient (Log Kow)’ version 1.03 – section 5; indicates the substance (constituents):

(i) All constituents fall within the Molecular Weight range domain.

(ii) No constituent substances have functional groups or features not in the training set of the model and/or for which no fragment constants and correction factors available. Constituents 8 and 9 contain multiple P=O fragment instances than the maximum of the training set although within the limit of the validation set (see QMRF title section 9.3 for more information). Constituent 1 is considered by the programme as ‘inorganic’ and therefore outside the training set domain and should be used with caution. Given the literature essentially indicates that the water solubility of phosphoric acid is > 850 g/L (ECHA, 2018) it should be considered that the model prediction is essentially correct given the water solubility intrinsic relationship with partition coefficient. A low value of Log Kow should be expected. Expert judgement would indicate that the extrapolated predictions appear adequate for all structures. The model can be extrapolated to substances outside the MW-fragment domain (as was done in the 372 substances outside the domain used in the model validation set. See QMRF title section 9.3 for more information).

The validation training sets included multiple phosphates, phosphonate and polyphosphate esters substances or equivalents along with measured data. The model appears to be acceptable in terms results for potential analogues.

 

3. Uncertainty of the prediction and mechanistic domain:

The training set of the model has the following statistics and coefficients of determination:

Total Training Set Statistics: number in dataset = 2447 ; correlation coef (r2) = 0.982 ; standard deviation = 0.217 ; absolute deviation = 0.159 and avg Molecular Weight = 199.98

The model has been externally validated on a set of 10,946 substances and the following statistics and coefficients of determination are presented:

Total Validation Set Statistics: number in dataset = 10946 ; correlation coef (r2) = 0.943 ; standard deviation = 0.479 ; absolute deviation = 0.356 ; avg Molecular Weight = 258.98

Data for the training set are available via external validation (see attached QMRF prepared by the applicant for full citations).

There is no overt mechanistic basis for the model. The model correlates thermodynamic relationships of surrogates to chemical activity. The KOWWIN v1.68 run in standalone mode allows Log Kow to be estimated based on measured values of analogues within the training set (if available). Then the model applies by adding/subtracting fragment constants and correction factors from the measured value. This therefore improves prediction since calculations are based on structural differences between target and analogue. The model domain ideally has at least one or more structurally similar substances to target substances on which to then apply ACF methodology. Whilst there appears to be no direct analogues within the training set. The model has been has been extensively validated externally (using > 10,000) substances with a correlation coefficient (r2) = 0.943. The model is non-proprietary and the training sets and validation sets can be downloaded from the internet. A summary of this information is presented by the applicant. Expert review of the data on relevant structural analogues in the validation dataset indicate that in general they over predict Log Kow compared to measured data. Model predictivity could be improved by the assignment of additional substances into the training set. Inclusion of additional structural fragments and expansion of sub-structure correction factors and related rules. In addition, rules for stereochemical effects could feasibly improve modelling.

Conclusions:

The results are adequate for the for the regulatory purpose.

Executive summary:

KOWWIN v1.68 (model publication: November 2012)

The range of constituents was: Log Kow = -1.7179 to 2.1995 in three blocks, respectively.

The majority of constituents had Log Kow = -0.7490 to 1.0627 and no constituents have predictions for Log Kow > 4.0.

 

Adequacy of the QSAR:

1) QSAR model is scientifically valid. 2) The substance falls within the applicability domain of the QSAR model or are considered scientifically plausible considering expert judgement. 3) The prediction is fit for regulatory purpose. The prediction is adequate for the Classification and Labelling or risk assessment of the substance as indicated in REACH Regulation (EC) 1907/2006: Annex XI Section 1.3. No substance constituents exceed the Log Kow = 4.0 cut-off. The assessment indicates that the prediction is suitable for the regulatory conclusion in accordance with the tonnage driven information requirements specifically when combined with further information available within the following report provided by the applicant: Aquatic Toxicity Predictions: Reaction products of 2‐hydroxyethyl methacrylate and diphosphorous pentoxide and water; dated: 30-05-2018.

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

14-10-2020 to 28-02-2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7570 (Partition Coefficient, n-octanol / H2O, Estimation by Liquid Chromatography)

Deviations:

no

GLP compliance:

yes

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

>= -0.8 - <= 2.8

Temp.:

35 °C

pH:

2

Remarks on result:

other: Six peaks (two coeluting, respective log Pow: -0.8, 0.6, 2.3, 2.4 and 2.8 Two peaks appear to be eluting at log Pow: 0.6 Calibration range: log Pow = 0.3 to 4.2 peak at log Pow - 0.8 (extrapolated)

Type:

log Pow

Partition coefficient:

>= -2 - <= 2.8

Temp.:

35 °C

pH:

7

Remarks on result:

other: Six peaks, (two eluting beyond the lower calibration range): respective log Pow: -2.0, 2.3, 2.4 and 2.8 Calibration range: log Pow = 0.3 to 4.2 peak at log Pow - 2.0 (extrapolated)

Preliminary assessment [Calculation Method]

Pow Calculation: the Pow of the test item was calculated to be 3.5 (log Pow 0.55) using the Rekker calculation method.

pKa Values : the pKa values in the logarithm range of 1 - 14 for acidic and basic groups in the molecular structure of the test item were calculated using the Perrin calculation method. The results indicated :

Acidic : XYP(O)OH           pKa 1.0

Basic : None.

 

HPLC method : pH 2

The results of the HPLC method are given in the Table 2. The calibration curve of the log k’ of the reference substances as function of log Pow had an regression line represented by the equation: log k’ = 0.360 ´ log Pow – 0.868 (r = 0.996, n = 12).

Table 2. Pow of the substance at pH 2

Substance	Retention time (min)			log Pow	Pow	Peak area (%)
	tr,1	tr,2	mean
Formamide (t0)	0.594	0.594	0.594
2-Butanone	0.693	0.693		0.3
Nitrobenzene	0.959	0.956		1.9
Toluene	1.534	1.530		2.7
1,4-Dichlorobenzene	1.988	1.983		3.4
Biphenyl	2.670	2.663		4.0
1,2,4-Trichlorobenzene	3.082	3.075		4.2
Test item – peak 1	0.634	0.634	0.634	-0.8 #1	1.4x10^-1	60
Test item – peak 2	0.732	0.731	0.732	0.6	4.4x10^0	22
Test item – peak 3	1.121	1.121	1.121	2.3	1.8x10^2	0.84
Test item – peak 4	1.173	1.172	1.173	2.4	2.4x10^2	14
Test item – peak 5	1.406	1.404	1.405	2.8	6.1x10^2	3.7

#1 : Log Pow is calculated by extrapolation of the calibration curve.

 

HPLC method : buffered pH 7

The results of the HPLC method are given in the Table 3. The calibration curve of the log k’ of the reference substances as function of log Pow had an regression line represented by the equation: log k’ = 0.360 ´ log Pow – 0.861 (r = 0.996, n = 12).

Table 3. Pow of the substance at pH 7

Substance	Retention time (min)			log Pow	Pow	Peak area (%)
	tr,1	tr,2	mean
Formamide (t0)	0.594	0.595	0.595
2-Butanone	0.695	0.695		0.3
Nitrobenzene	0.963	0.963		1.9
Toluene	1.546	1.546		2.7
1,4-Dichlorobenzene	2.003	2.005		3.4
Biphenyl	2.696	2.702		4.0
1,2,4-Trichlorobenzene	3.105	3.111		4.2
Test item – peak 1	0.479	0.481	0.480	n.a.	n.a.	60
Test item – peak 2	0.571	0.573	0.572	n.a.	n.a.	20
Test item – peak 3	0.609	0.612	0.611	-2.0 #1	1.1x10^-2	1.6
Test item – peak 4	1.128	1.131	1.130	2.3	1.8x10^2	0.87
Test item – peak 5	1.181	1.183	1.182	2.4	2.4x10^2	14
Test item – peak 6	1.423	1.426	1.425	2.8	6.2x10^2	3.5

#1 : Log Pow is calculated by extrapolation of the calibration curve.

n.a. : Not applicable, log Pow for peak 1 and peak 2 could not be calculated since the retention time is lower than the dead time (t0).

 

Table 4. Summary of test item data:

	pH 2			pH 7
	Pow	log Pow	Peak area (%)	Pow	log Pow	Peak area (%)
Test item – peak 1	1.4x10^-1	-0.8 #1	60	n.a.	n.a.	60
Test item – peak 2	4.4x10^0	0.6	22	n.a.	n.a.	20
Test item – peak 3	-	-	-	1.1x10^-2	-2.0 #1	1.6
Test item – peak 4	1.8x10^2	2.3	0.84	1.8x10^2	2.3	0.87
Test item – peak 5	2.4x10^2	2.4	14	2.4x10^2	2.4	14
Test item – peak 6	6.1x10^2	2.8	3.7	6.2x10^2	2.8	3.5

#1 : Log Pow is calculated by extrapolation of the respective pH, calibration curves.

n.a. : Not applicable, log Pow for peak 1 and peak 2 could not be calculated since the retention time is lower than the dead time (t0).

 

Within the partition coefficient determination: based on preliminary assessment of the test item it was decided to perform the HPLC method test, initially at pH 4 and pH 7. Subsequently, it was decided to use pH 2 rather than pH 4. This was on the basis that at pH 4, two of the main test item peaks eluted prior to the reference item calibration range. At pH 2 all peaks were within the calibration range or could yield an extrapolated log Pow from the calibration curve. For that reason, the HPLC method test was performed at pH 2 and pH 7.

 

Applicant assessment indicates:

(i) Only inorganic orthophosphoric acid is expected to be 50% ionised at pH 2 (i.e. pKa = 1.0). All other components should be non-ionised

(ii) At pH 7 increased ionisation is expected to occur of inorganic phosphate moieties and/or organic phosphate moieties with pH (i.e. between pH 2 and pH 9 water solubility increases and lipophilicity is expected to decrease).

(iii) Other (non-phosphate) moieties such as hydroxyl- acidic -H, have calculated pKa > 12 in public models. They therefore are not relevant to behaviour in the environmental pH range.

Applicant assessment of the data presented in the study report indicates:

(i) Peak 3: within the pH 2 determination it appears that peak 3 coelutes with peak 2 at log Pow = 0.6 (presumably when this component is in a non-ionised form). At pH 7 and its ionised form, peak 3 is extrapolated to elute at log Pow = -2.0.

(ii) Peak 1 and peak 2 : these components are presumably within their ionised forms at pH 7. These eluted beyond the log Pow lower calibration range and/or beyond the range where extrapolation could be made. These components essentially have a log Pow < -2.0 at pH 7. Whereas when non-ionised at pH 2, these components have log Pow in the range of -0.8 to 0.6.

(iii) At pH 4, based on the data presented in the report: it can be considered that peak 1, peak 2 and peak 3 would have log Pow < -2.0 to 0.3 as sensible “limit values”. Since increasing ionisation would lower their log Pow (and/or lower lipophilicity and/or increase water solubility). Whereas: peak 4, peak 5 and peak 6 would have unchanged log Pow, based on interpolation of the data presented for the test item at pH 2 and pH 7. Belonging to components where log Pow is unchanged by increasing pH.

 

In summary, it can be considered that the test item consists of blocks of components that range from extremely low log Pow to low Pow at pH 4 to pH 7:

Block 3: log Pow = -2.0 to 0.6 (highly water soluble/essentially ‘miscible’, > 10000 mg/L)

Block 2: log Pow = 0.6 to 2.0 (water soluble, > 1000 mg/L)

Block 1: log Pow 2.1 to 2.8 (slightly soluble, 1 – 100 mg/L)

 

This correlates to and confirms the KOWWIN v1.68 predictions provided separately (for all identified constituents). The HPLC screening test confirms no constituents are expected to have a log Pow > 3.0 at pH 4, pH 7 or pH 9.

Conclusions:

The partition coefficient of the test item was determined to be as follows:
(i) at 35 °C pH 2: log Pow range = ≥ -0.8 to ≤ 2.8 ; with six peaks (two coeluting), respective log Pow: -0.8, 0.6 (coelution of two peaks), 2.3, 2.4 and 2.8
peak at log Pow - 0.8 (extrapolated) as beyond lower limit of calibration range: log Pow = 0.3 to 4.2
(ii) at 35 °C buffered pH 7: ≥ -2.0 to ≤ 2.8 ; with six peaks, and two eluting beyond the lower calibration range, respective log Pow: -2.0, 2.3, 2.4 and 2.8
peak at log Pow – 2.0 (extrapolated) as beyond lower limit of calibration range: log Pow = 0.3 to 4.2
The HPLC screening test confirms no constituents are expected to have a log Pow > 3.0 at pH 4, pH 7 or pH 9

Executive summary:

The n-octanol/water partition coefficient was determined using the HPLC method within OECD TG 117, EU Method A.8 and US EPA OPPTS 830.7570 in accordance with GLP. The test item was tested at multiple pH. Within the partition coefficient determination: based on preliminary assessment of the test item it was decided to perform the HPLC method test, initially at pH 4 and pH 7. Subsequently, it was decided to use pH 2 rather than pH 4. This was on the basis that at pH 4, two of the main test item peaks eluted prior to the reference item calibration range. At pH 2 all peaks were within the calibration range or could yield an extrapolated log Pow from the calibration curve. For that reason, the HPLC method test was performed at pH 2 and pH 7. Calibrations for each pH were completed individually. A 1000 mg/L stock solution of the test item was prepared in methanol. The stock solution was 100-fold diluted to obtain an end solution of 75/25 (v/v) methanol/water pH 2 or 75/25 (v/v) methanol/0.01 M phosphate buffer pH 7, as applicable . The final concentration of the test substance solution was 10.0 mg/L injected at 5 µL into the respective mobile phases of: pH 2: 75/25 (v/v) methanol/water or pH 7: 75/25 (v/v) methanol/0.01 M phosphate buffer. Samples of the test item were analysed via HPLC on a C18 column with TUV UV/visible wavelength detector at 210 nm. Calibration was performed using six reference items with known log POW values (given by the guidelines). Calibrations for each pH were completed individually. The dead time (t0) of the HPLC system was determined with Formamide for each pH individually. The dead time and the reference items were measured in duplicate. The test item was injected and measured in duplicate. The partition coefficient of the test item was determined to be as follows: (i) at 35 °C pH 2: log Pow range = ≥ -0.8 to ≤ 2.8 ; with six peaks (two coeluting), respective log Pow: -0.8, 0.6 (coelution of two peaks), 2.3, 2.4 and 2.8, with the peak at log Pow - 0.8 (extrapolated) as beyond lower limit of calibration range: log Pow = 0.3 to 4.2 ; (ii) at 35 °C buffered pH 7: ≥ -2.0 to ≤ 2.8 ; with six peaks, and two eluting beyond the lower calibration range, respective log Pow: -2.0, 2.3, 2.4 and 2.8 peak at log Pow – 2.0 (extrapolated) as beyond lower limit of calibration range.

Applicant assessment indicates: it can be considered that the test item consists of blocks of components that range from extremely low log Pow to low Pow at pH 4 to pH 7:

Block 1: log Pow = -2.0 to 0.6 (highly water soluble/essentially ‘miscible’, > 10000 mg/L); Block 2: log Pow = 0.6 to 2.0 (water soluble, > 1000 mg/L) and/or Block 3: log Pow 2.1 to 2.8 (slightly soluble, 1 – 100 mg/L). The HPLC screening test confirms no constituents are expected to have a log Pow > 3.0 at pH 4, pH 7 or pH 9.

Description of key information

log Pow (HPLC) : OECD TG 117, 2021

(i) at 35 °C pH 2: log Pow range = ≥ -0.8 to ≤ 2.8 ; with six peaks (two coeluting), respective log Pow: -0.8, 0.6 (coelution of two peaks), 2.3, 2.4 and 2.8

peak at log Pow - 0.8 (extrapolated) as beyond lower limit of calibration range: log Pow = 0.3 to 4.2

(ii) at 35 °C buffered pH 7: ≥ -2.0 to ≤ 2.8 ; with six peaks, and two eluting beyond the lower calibration range, respective log Pow: -2.0, 2.3, 2.4 and 2.8

peak at log Pow – 2.0 (extrapolated) as beyond lower limit of calibration range: log Pow = 0.3 to 4.2

The HPLC screening test confirms no constituents are expected to have a log Pow > 3.0 at pH 4, pH 7 or pH 9.

It can be considered that the test item consists of blocks of components that range from extremely low log Pow to low Pow at pH 4 to pH 7:

Block 3: log Pow = -2.0 to 0.6 (highly water soluble/essentially ‘miscible’, > 10000 mg/L)

Block 2: log Pow = 0.6 to 2.0 (water soluble, > 1000 mg/L)

Block 1: log Pow 2.1 to 2.8 (slightly soluble, 1 – 100 mg/L)

 

The key value for chemical safety assessment is determined at 2.8, the highest log Kow value, corresponding to the worst case scenario.

 

Supporting information:

Calculated log Kow (range): -1.7179 to 2.1995 in three blocks, respectively, at 25 °C; ca. pH 7, QSAR Prediction - KOWWIN v1.68, 2018

The majority of constituents had Log Kow = -0.7490 to 1.0627 and no constituents have predictions for Log Kow > 4.0.

Key value for chemical safety assessment

Log Kow (Log Pow):

2.8

at the temperature of:

35 °C

Additional information

Key study : OECD TG 117, 2021 : The n-octanol/water partition coefficient was determined using the HPLC method within OECD TG 117, EU Method A.8 and US EPA OPPTS 830.7570 in accordance with GLP. The test item was tested at multiple pH. Within the partition coefficient determination: based on preliminary assessment of the test item it was decided to perform the HPLC method test, initially at pH 4 and pH 7. Subsequently, it was decided to use pH 2 rather than pH 4. This was on the basis that at pH 4, two of the main test item peaks eluted prior to the reference item calibration range. At pH 2 all peaks were within the calibration range or could yield an extrapolated log Pow from the calibration curve. For that reason, the HPLC method test was performed at pH 2 and pH 7. Calibrations for each pH were completed individually. A 1000 mg/L stock solution of the test item was prepared in methanol. The stock solution was 100-fold diluted to obtain an end solution of 75/25 (v/v) methanol/water pH 2 or 75/25 (v/v) methanol/0.01 M phosphate buffer pH 7, as applicable . The final concentration of the test substance solution was 10.0 mg/L injected at 5 µL into the respective mobile phases of: pH 2: 75/25 (v/v) methanol/water or pH 7: 75/25 (v/v) methanol/0.01 M phosphate buffer. Samples of the test item were analysed via HPLC on a C18 column with TUV UV/visible wavelength detector at 210 nm. Calibration was performed using six reference items with known log POW values (given by the guidelines). Calibrations for each pH were completed individually. The dead time (t0) of the HPLC system was determined with Formamide for each pH individually. The dead time and the reference items were measured in duplicate. The test item was injected and measured in duplicate. The partition coefficient of the test item was determined to be as follows: (i) at 35 °C pH 2: log Pow range = ≥ -0.8 to ≤ 2.8 ; with six peaks (two coeluting), respective log Pow: -0.8, 0.6 (coelution of two peaks), 2.3, 2.4 and 2.8, with the peak at log Pow - 0.8 (extrapolated) as beyond lower limit of calibration range: log Pow = 0.3 to 4.2 ; (ii) at 35 °C buffered pH 7: ≥ -2.0 to ≤ 2.8 ; with six peaks, and two eluting beyond the lower calibration range, respective log Pow: -2.0, 2.3, 2.4 and 2.8 peak at log Pow – 2.0 (extrapolated) as beyond lower limit of calibration range.

Applicant assessment indicates: it can be considered that the test item consists of blocks of components that range from extremely low log Pow to low Pow at pH 4 to pH 7: Block 3: log Pow = -2.0 to 0.6 (highly water soluble/essentially ‘miscible’, > 10000 mg/L); Block 2: log Pow = 0.6 to 2.0 (water soluble, > 1000 mg/L) and/or Block 1: log Pow 2.1 to 2.8 (slightly soluble, 1 – 100 mg/L). The HPLC screening test confirms no constituents are expected to have a log Pow > 3.0 at pH 4, pH 7 or pH 9.

Key Data : QSAR Predictions KOWWIN v1.68 model, 2018 :

The range of constituents was: Log Kow = -1.7179 to 2.1995 in three blocks, respectively.

The majority of constituents had Log Kow = -0.7490 to 1.0627 and no constituents have predictions for Log Kow > 4.0.