Phosphoric acid, ethyl ester

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014-07-07 - 2014-07-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2014

Report date:

2014

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

calculation method (fragments)

Partition coefficient type:

octanol-water

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl dihydrogen phosphate

EC Number:

216-603-9

EC Name:

Ethyl dihydrogen phosphate

Cas Number:

1623-14-9

Molecular formula:

C2H7O4P

IUPAC Name:

Phosphoric acid,monoethyl ester

Test material form:

liquid

Specific details on test material used for the study:

Test item:Hordaphos MDE
Synonym:phosphoric acid ethyl ester, ethyl phosphate
Content:99.2 % (sum of main components)
Physical state:colourless to brownish clear viscous liquid
CAS-No.:37203-76-2
EINECS-No.:253-391-7

Study design

Analytical method:

other: calculation

Results and discussion

Partition coefficient

Key result

Type:

log Pow

Partition coefficient:

>= -0.14 - <= 0.32

Temp.:

20 °C

Remarks on result:

other: pH not determined

Any other information on results incl. tables

 Preliminary estimation of the water solubility

In a stepwise procedure, increasing volumes of distilled water were added at room temperature to adefined amount of the test item. The mixtures were shaken and visually checked for any undissolvedparts. According to the observed high solubility of the test item an additional preliminary test wasperformed where to 1 ml of water defined amounts of the test item were added. The mixtures wereshaken and visually checked for any undissolved parts.

Preliminary estimation of the n-octanol solubility

A defined amount of the test item was stirred with a defined volume of n-octanol at roomtemperature and visually checked for any undissolved parts.

If the estimated log P_owis above zero, the partition coefficient n-octanol / water of the test item atroom temperature can be determined with the HPLC method. Log P_owvalues in the range -2 to 4can be experimentally determined by the Shake-Flask method.

Preliminary and principal visual estimation of the water solubility

To 112 mg of the test item 0.1 ml water was added at room temperature. The mixture appeared dissolved. According to the observed high solubility of the test item an additional preliminary test was performed were to 1 ml of water 1.025 g of the test item was added. The mixture was shaken and visually checked for any undissolved parts. According to the preliminary visual estimation the water solubility of the test item was >1025 g/l.

Due to the results of the preliminary test it was assumed that the test item was completely miscible with water and a special "visual method"was applied for the main test in order to investigate the complete miscibility of the test item. In the main test of the water solubility it was shown, that the test item was miscible with water at room temperature (T=23 °C) and at T = 20.0 °C ± 0.5°Cin any ratio.

Preliminary visual estimation of the n-octanol solubility

A defined amount of the test item was stirred with increasing amounts of n-octanol at room temperature and visually checked for any undissolved parts.

The solubility of the test item in n-octanol was found to be higher than 9 kg/I (without correction ofthe purity). Thus it can be stated that the test item is miscible with n-octanol at room temperature.

The shake-flask method applies only to essentially pure substances soluble in water and n-octanoland therefore is not suitable for the test item according to EC 440/2008.

Referring to the guidance on information requirements and chemical safety assessment, chapterR.7a: endpoint specific guidance, dated February 2014, of the European Chemicals Agency, theHPLC method is very suitable for measuring the n-octanol-water-partition coefficient of mixtures ofchemical homologues. But the test item is not UV active. For this reason no appropriate detectionsystem is available to perform the HPLC method (see OECD 117).

From the chemical structure it can be assumed that the components of the test item show differentsolubility in n-octanol. Therefore, an estimation of the partition coefficient using the single solubilitiesof the test item in water and n-octanol was not possible and not sensible as well.

Thus the partition coefficient of the organic parts of the test item was evaluated with EPI Suite.

According to the certificate of analysis the test item consists of water miscible compounds suchasphosphoric acid and ethanol. The theoretical value of the n-octanol-water-partition coefficient of thecomponents of the test item was calculated with EPIWIN (EPI Suite ™)-software, v 4.10, SyracuseResearch Corp., Environmental Protection Agency).

Estimated n-octanol-water partition coefficients by EPIWIN:

compound	Assay in wt.-%	log Pow
phosphoric acid	5.3	*
2-Ethanol	4.9	-0.14
Mono ethyl phosphate	62.2	-0.22
Di ethyl phosphate	26.6	+0.32

Applicant's summary and conclusion

Conclusions:

The calculated individual values of the organic components are in the range -0.14 to 0.32.
log Kow = -0.14 to 0.32

Executive summary:

The shake-flask method applies only to essentially pure substances soluble in water and n-octanoland therefore is not suitable for the test item according to EC 440/2008.

Referring to the guidance on information requirements and chemical safety assessment, chapterR.7a: endpoint specific guidance, dated February 2014, of the European Chemicals Agency, theHPLC method is very suitable for measuring the n-octanol-water-partition coefficient of mixtures ofchemical homologues. But the test item is not UV active. For this reason no appropriate detectionsystem is available to perform the HPLC method (see OECD 117).

From the chemical structure it can be assumed that the components of the test item show different solubility in n-octanol. Therefore, an estimation of the partition coefficient using the single solubilities of the test item in water and n-octanol was not possible and not sensible as well.

Thus the partition coefficient of the organic parts of the test item was evaluated with EPI Suite.

According to the certificate of analysis the test item consists of water miscible compounds such as phosphoric acid and ethanol. The theoretical value of the n-octanol-water-partition coefficient of the components of the test item was calculated with EPIWIN (EPI Suite ™)-software, v 4.10, SyracuseResearch Corp., Environmental Protection Agency).

The calculated individual values of the organic components are in the range -0.14 to 0.32.

log Kow = -0.14 to 0.32