tert-butyl 3,5,5-trimethylperoxyhexanoate

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2010-02-23 to 2010-03-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

5.16

Temp.:

25 °C

Key result

Type:

Pow

Partition coefficient:

142 923

Temp.:

25 °C

Details on results:

The partition coefficient Pow was determined based on a calibration curves using nine reference items.
The capacity factors k were calculated from the dead time and retention times of the reference substances. The log k data of the reference substances were plotted against their log Pow values.

Measured and calculated data of TBPIN:

Chemical name	Retention time (min)	log k	log Pow	Pow	Repeatability log unit
		Calculated
TBPIN	15.31	0.701	5.16	143631	0.0
	15.31	0.701	5.16	143631
	15.29	0.701	5.15	142781
	15.29	0.701	5.15	142781
	15.28	0.700	5.15	142357
	15.28	0.700	5.15	142357
Mean	15.29	0.701	5.16	142923	-
Conf.int.(95%)	0.01	-	0.002	609	-
CV%	0.1	-	-	-	-

Conclusions:

The log Pow is determined to be 5.16 ± 0.002 (with 95 % confidence interval). The estimated Pow is 142923 ± 609 (with 95 % confidence interval).

Executive summary:

The partition coefficient Pow of tert-Butylperoxy-3,5,5-trimethylhexanoat was determined using HPLC. The test item was dissolved in acetonitrile. The concentration of this solution was 1 mg/mL. It was diluted with eluent to 100 μg/mL. The partition coefficient Pow was determined based on a calibration curves using nine reference substances. The capacity factors k were calculated from the dead time and retention times of the reference substances. The log k data of the reference substances were plotted against their log Pow values.

The log Pow is determined to be 5.16 ± 0.002 (with 95 % confidence interval). The estimated Pow is 142923 ± 609 (with 95 % confidence interval) at 25 °C. Quality criteria were met, as values of log P derived from individual measurements fell within a range of 0.1 log units.

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2014-09-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study is regarded as reliable without restrictions because it was conducted in compliance with GLP regulation and guideline. Deficiencies: The pH value of the test solution was not measured. This deviation has no influence on the outcome of this study as the test item does not contain any ionic structure which can be affected by the pH value.

Qualifier:

according to guideline

Guideline:

OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)

Version / remarks:

dated 2006-03-22

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Regualtion (EC) 440/2008 Part A. A.28 dated 2014-01-24

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

4.4

Temp.:

25 °C

Remarks on result:

other: The pH value of the test solution was not measured. This has no influence on the outcome of this study as the test item does not contain any ionic structure which can be affected by the pH value.

Key result

Type:

Pow

Partition coefficient:

27 000

Temp.:

25 °C

Remarks on result:

other: The pH value of the test solution was not measured. This has no influence on the outcome of this study as the test item does not contain any ionic structure which can be affected by the pH value.

Details on results:

The concentration of test substance in the 1-octanol and water phase was analysed after 24 hours The log Pow values of the replicates were calculated using the final concentrations.

Results of preliminary test

The concentration of test substance in the 1-octanol and water phase, analysed at the different time points.

Time	Octanol phase			Water phase
point	meas. conc.	dilution	final conc.	meas. conc.	dilution	final conc.	Pow	log Pow
hrs	mg/L	factor	µg/L	µg/L	factor	µg/L
24	324.6	10	3245554	94.0	1	94.0	3.5.E+04	4.5
29	322.0	10	3219719	101.3	1	101.3	3.2.E+04	4.5
48	329.8	10	3298345	98.4	1	98.4	3.4.E+04	4.5
72	259.1	10	2591083	93.5	1	93.5	2.8.E+04	4.4
						Average	3.2.E+04	4.5
						St. dev.		0.042
						p-value		0.010

 

The logarithmic values of partition coefficient octanol/water (log Pow), calculated using the final concentrations of the test substance at four consecutive time points, showed no significant difference over the several time points. For practical reasons, an equilibration period of 24 hours was chosen to be used during the definitive test.

 

 

Results of definitive test

The concentration of test substance in the 1-octanol and water phase was analysed after 24 hours.

	Octanol phase			Water phase
Replicate	meas. conc.	dilution	final conc.	meas. conc.	dilution	final conc.	Pow	log Pow
	mg/L	factor	µg/L	µg/L	factor	µg/L
1	273.4	10	2733820	100.9	1	100.9	2.7.E+04	4.4
2	278.3	10	2782533	100.6	1	100.6	2.8.E+04	4.4
3	273.1	10	2731056	102.5	1	102.5	2.7.E+04	4.4
						Average	2.7.E+04	4.4
						St. dev.		0.008

 

Conclusions:

Using the slow -stirring method the log Pow was determined to be 4.4 at 25 °C.

Executive summary:

A study was conducted according to OECD TG 123 and Regulation (EC) 440/2008 part A A.28 to determine the log Pow of the test item. In a preliminary test the length of the equilibration period was assessed. At time points 24, 29, 48 and 72 hours after adding the test substance, the concentration of the test substance was determined in both the 1-octanol and water phase using a HPLC method. The logarithmic values of partition coefficient octanol/water (log Pow), calculated using the final concentrations of the test substance at four consecutive time points, showed no significant difference over the several time points. A stirring time of 24 hours was chosen to be applied in the definitive test. Three reaction vessels were filled with 980 mL of octanol saturated water and with 20 mL test item dissolved in water saturaed octanol. The test was performed in the dark and at a temperature of 25 ± 1°C. At 24 hours after adding the test substance, stirring was stopped and samples were taken from the octanol as well as the water phase. The log Pow values of the replicates were calculated using the final concentrations. The average log Pow value for the test substance was calculated to be 4.4 at 25 °C.

Description of key information

Using the slow-stirring method according to OECD TG 123 the log Pow was determined to be 4.4 at 25 °C.

Key value for chemical safety assessment

Log Kow (Log Pow):

4.4

at the temperature of:

25 °C

Additional information

Slow stirring method

A study was conducted according to OECD TG 123 and Regulation (EC) 440/2008 part A A.28 to determine the log Pow of the test item. In a preliminary test the length of the equilibration period was assessed. Using a HPLC method at time points 24, 29, 48 and 72 hours after adding the test substance, the concentration of the test substance was determined in both the 1-octanol and water phase. The logarithmic values of partition coefficient octanol/water (log Pow), calculated using the final concentrations of the test substance at four consecutive time points, showed no significant difference over the several time points. A stirring time of 24 hours was chosen to be applied in the definitive test. Three reaction vessels were filled with 980 mL of octanol saturated water and 20 mL of test item dissolved in water saturated octanol and thermostated. The test was performed in the dark and at a temperature of 25 ± 1 °C. At 24 hours after adding the test substance, stirring was stopped and samples were taken from the octanol as well as the water phase. The log Pow values of the replicates were calculated using the final concentrations. The average log Pow value for the test substance was calculated to be 4.4 at 25 °C.

 

HPLC method

The partition coefficient Pow of tert-Butylperoxy-3,5,5-trimethylhexanoat was determined using HPLC. The test item was dissolved in acetonitrile. The concentration of this solution was 1 mg/mL. It was diluted with eluent to 100 μg/mL. The partition coefficient Pow was determined based on a calibration curves using nine reference substances. The capacity factors k were calculated from the dead time and retention times of the reference substances. The log k data of the reference substances were plotted against their log Pow values. The log Pow was determined to be 5.16 ± 0.002 (with 95 % confidence interval). The estimated Pow is 142923 ± 609 (with 95 % confidence interval) at 25 °C. Quality criteria were met, as values of log P derived from individual measurements fell within a range of 0.1 log units.

 

Conclusion

The HPLC method according to OECD TG 107 was conducted to estimate the logPow of the test item. Using the HPLC method the log Pow was not measured directly but from a correlation between log k (capacity factor) and log Pow or a series of reference substances. It therefore depends on the choice of reference substances. The log Pow was determined to be 5.16 at 20 °C. The log Pow value was close to the threshold value of 5.00 used in chemical safety assessment. Thus, for a more accurate determination of the log Pow a second study was conducted in accordance with OECD TG 123. Three independent trials were conducted. The concentration of the test item in each phase was determined using a HPLC-UV method. The average logPow of the three trails was calculated to be 4.4. The logPow value determined using slow-stirring method was regarded to be more reliable as the concentration of the test item in each phase was measured directly after the equilibrium was reached.

Therefore, a logPow of 4.4 was chosen as key value for chemical safety assessment.