Diammonium tartrate

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-11-02 to 2015-12-04

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Due to very low lipophilicity study could not be conducted according to OECD guidelines for this endpoint. Instead logPow was calculated by determination of solubilities in water and n-octanol seperately. Determination of water solubility was done according to EU Method A.6. (Water Solubility) and OECD Guideline 105, (Water Solubility). Determination of solubilitiy in n-octanol was based on the principle of EU Method A.6. (Water Solubility) and OECD Guideline 105, (Water Solubility). No information is given about the pH value in the test system.

Qualifier:

equivalent or similar to guideline

Guideline:

other: logPow was calculated by determination of solubilities in water and n-octanol separately. Determinations of water and octanol solubilities were done according to EU Method A.6. (Water Solubility) and OECD Guideline 105, (Water Solubility).

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - Shake Flask Method)

Principles of method if other than guideline:

Estimation based on determination of individual solubilities in n-octanol and water. The individual solubilities are conducted according to guideline EU Method A.6 and OECD guideline 105 for water solubility and based on these guidelines for n-octanol solubility determination.

GLP compliance:

no

Type of method:

other: based on determination of ratio n-octanol solubility vs. aqueous solubility. Solubility determination accordingto OECD guideline 105.

Partition coefficient type:

octanol-water

Analytical method:

liquid chromatography

Type:

log Pow

Partition coefficient:

-5.6

Temp.:

20 °C

Remarks on result:

other: log Pow calculated by solubility(n-octanol)/solubility(water). Determined solubility in n-octanol 0.2mg/L

In the preliminary tests substance concentrations were 10 mg/L, 1 mg/L and 0.1 mg/L. Visual inspection showed that the mixture is not dissolved. Overall stirring time was about 24 hours. Combined with the preliminary solubility tests in water (solubility=116 g/L) calculated logPow < -3.1

In the main test, solubility in n-Octanol was determined by measuring ammonium concentration. The resulting ammonium concentrations were 0.2 mg/L at 20°C after 72 hrs stirring time. Concentrations for 24 and 48 hrs stirring time were <0.2 mg/L for 24 hrs and 48 hrs stirring time. Solubility of the test item in water was reported in test report reference [4.8.-1]. Ammonium concentration in water was determined to be 83900 mg/L. Calculated logPow = -5.6.

Description of key information

log P_OW= -5.6 at 20 °C (A.8. calculation method based on solubilities in water and n-octanol))

Key value for chemical safety assessment

Log Kow (Log Pow):

-5.6

at the temperature of:

20 °C

Additional information

Due to the low expected partition coefficient standard methods like shake-flask method or HPLC method could not be applied. Instead logPow was estimated by calculation of the ratios of test substance in octanol vs. water. Whereas solubility in water was already determined by another test (428 g/L at pH=6.2 and 20°C; see test report reference [4.8 -1]), solubility in 1-octanol was to be determined by this test. The test was based on OECD guideline 105 and EU Method A.6. and conducted in 3 different flasks with stirring times of 1, 2 and 3 days. In the 1 -octanol extracts, concentration of ammonium ions was determined. As analytical method ion chromatography with a conductivity detector was applied. The resulting logPow (-5.6) refers to 20°C and pH value of 6.2 of the aqueous phase.