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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EPA OPPTS 830.7570 (Partition Coefficient, n-octanol / H2O, Estimation by Liquid Chromatography)
Qualifier:
according to guideline
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Qualifier:
according to guideline
Guideline:
other: TSCA Title 40 of the Federal Code of Regulations, Part 796, Section 1570: Partition coefficient (n-octanol/water)
GLP compliance:
yes (incl. QA statement)
Remarks:
Exception: The characterization and stability of the test and reference substances under storage conditions at the test site were not determined in accordance with GLP Standards
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
The substance name 3.5 G FF is one of the commenrcial names for p-t-butylphenyldiphenyl phosphate and bis(p-t-butylphenyl) phenyl phosphate
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
3.85
Remarks on result:
other: Peak 1 (TPP or triphenyl phosphate)
Key result
Type:
log Pow
Partition coefficient:
5.61
Remarks on result:
other: Peak 2 ("C4" or t-butylphenyldiphenyl phosphate)
Type:
log Pow
Partition coefficient:
> 6.5
Remarks on result:
other: Peak 3 ("C8" or di-t-butylphenylphenyl phosphate)
Type:
log Pow
Partition coefficient:
> 6.5
Remarks on result:
other: Peak 4 ("C12" or tri-t-butylphenyl phosphate)
Conclusions:
Under the chromatographic conditions specified, 3.5 G FF eluted as four discrete peaks, ranging in mean log Pow of 3.86 to > 6.5. The mean log Pow for the largest peak, according to percent area, in 3.5 G FF was 5.61 0.002 log units (N=3, RSD = 0.039%).
Executive summary:

Injections of a reagent blank solution (75% ACN: 25% H2O (v/v)) showed that the reagents used

for preparation of the combined calibration reference standard solutions and 3.5 G FF solutions were free of any potentially interfering contaminants.

Two reference standard solutions comprised of a total of eight reference substances were

prepared and injected in at least triplicate (once near the beginning, one after every four injections and

once near the end of the HPLC sequence). The retention times for one of the reference substances in one

of the standard solutions, thiourea, were used to determine the analytical column dead time (t0) for use in

calculating capacity factors (k) of the remaining reference substances and the test substance. The mean

retention time of thiourea was 1.663 minutes on the UV detector. Seven additional reference substances

contained in the two reference standard solutions were analyzed. The capacity factors of all the reference

substances were calculated based upon their retention times.

The three 100-mg/L 3.5 G FF solutions were sequentially injected. 3.5 G FF eluted as four peaks

on the UV detector. The mean retention time of each peak was 4.277, 9.242, 22.798 and 25.260 minutes,

respectively. Based on the test substance composition stated earlier and the mean percent area of 2.23%,

80.7%, 16.1%, and 0.974% for each peak, the four peaks are most likely TPP, C4, C8, and C12,

respectively. Immediately following the injections of the 100-mg/L test substance solutions, a 500-mg/L

test substance solution was injected to confirm which peaks were from the test substance. Since the third

and fourth peaks of the test substance had to be driven off the column by way of a stronger mobile phase

than used for the elution of the reference substances, the log POW for the third and fourth peaks of the test

substance was reported as greater than the highest POW reference substance, DDT (log POW = 6.5). The

capacity factors (k) of each test substance peak were then calculated based on the corresponding retention

time. The corresponding mean log POW for each 3.5 G FF peak was calculated as 3.85, 5.61, > 6.5, and

> 6.5, respectively. A log POW value within 0.45 log units (3.4) for TPP was reported in another study

using the HPLC-estimation method. The OECD Guideline states that the reproducibility of

HPLC-estimation methods should be within ± 0.5 log units.

Description of key information

Key value for chemical safety assessment

Log Kow (Log Pow):
5.61
at the temperature of:
20 °C

Additional information