Registration Dossier

Administrative data

Endpoint:
partition coefficient
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
key study
Study period:
March 2006 - October 2006
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2006
Report date:
2006

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
The partition coefficient of test substance UL125 has been estimated from the individual solubility of test substance in distilled water and n-octanol due to its surface active nature.

Approximately 7.9g – 9.4g of test substance UL125, ASG 10379810, was accurately weighed, in duplicate, into a 100ml conical flask. 25.0ml of n-octanol was added to each. The flasks were placed in a stirring water bath and were stirred overnight at 25°C ± 1°C. After overnight stirring, the magnetic stirrer was switched off and the flasks were left to stand in the bath for approximately 2 hours at 25°C ± 1°C. The test solutions were then filtered through Millipore HVLP filters, under gravity, and clear filtrates were obtained.

The filtrates were diluted 1.0ml to 100.0ml eluent B and then further diluted 1.0ml to
100.0ml eluent B and analysed by HPLC.

Mean n-Octanol solubility of test substance UL125, ASG 10379810, = 21.0% w/v.
Test 1 = 217000mg/l (21.7%w/v)
Test 2 = 203000mg/l (20.3%w/v)

Approximately 0.5g – 0.6g of test substance UL125, ASG 10379810, was accurately weighed, in duplicate, into a 100ml conical flask. 100.0ml of distilled, deionised water was added to each. The flasks were placed in a stirring water bath and were stirred overnight at 25°C ± 1°C. After overnight stirring, the magnetic stirrer was switched off and the flasks were left to stand in the bath for approximately 30mins at 25°C ± 1°C. The test solutions were then filtered through 0.45μm Millipore cellulose nitrate filters and clear filtrates were obtained.

The pH pf the filtrates were measured and the filtrates analysed without further dilution by HPLC.
Mean water solubility of test substance UL125, ASG 10379810, = 35.1 mg/l (average pH 7.5)
Test 1 = 35.0mg/l (pH 7.6)
Test 2 = 35.2mg/l (pH 7.4)

Solubility Results

Water Solubility: 35.1mg/l at 25oC ± 1oC
n-Octanol Solubility : 21.0%w/v (210000mg/l) at 25°C ± 1°C

Calculation of Log Pestimated Value


P estimated = (solubility in n-octanol / solubility in distilled water)

P estimated = (210000 / 35.1) = 5982.91

Log P = 3.78
Therefore Log Pestimated = 3.8 at 25°C ± 1°C
GLP compliance:
yes
Type of method:
estimation method (solubility ratio)
Partition coefficient type:
octanol-water

Test material

Constituent 1
Test material form:
solid: particulate/powder
Details on test material:
Light pink tinted powder

Study design

Analytical method:
other: HPLC

Results and discussion

Partition coefficient
Type:
log Pow
Partition coefficient:
3.8
Temp.:
25 °C
pH:
> 7.5

Applicant's summary and conclusion