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Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 9 August to 6 september 2011
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study was considered without restriction. No observations were made which might cause doubts concerning the validity of the study outcome.
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 105 (Water Solubility)
Version / remarks:
with modifications
GLP compliance:
yes (incl. certificate)
Type of method:
flask method
Key result
Water solubility:
ca. 2.19 mg/L
Temp.:
20 °C
pH:
ca. 3.3
Remarks on result:
other: pH measured from 21 days to 28days was ranged from 3.32 to 3.46
Details on results:
The test substance appeared to reach equilibrium after 21 days of slow-stir mixing. The mean water solubility calculated from the day 21 and day 28 replicates n=6 is 2.19mg/L with relative standard deviation of 4.6%.

Results:

the individual and mean measured alpha-pinebe water solubility concentrations determined at each weekly sampling interval along with calculated standards deviation (SD) and relative standard deviation (RSD).

Table 1 lists of water solubility of alpha-pinene:

 Time (days)  alpha-Pinene (mg/l)  interval mean (mg/L)  SD  RSD
 7  1.77      
 7 1.86       
 7  1.64  1.76  0.11  6.3%
 14  2.24      
 14  1.72      
 14  1.97  1.98  0.26  13%
 21  2.31      
 21  2.08      
 21  2.09  2.16  0.13  6.0%
 28  2.29      
 28  2.16      
 28  2.23  2.23 0.065   2.9%
      reported mean       days 21 and 28 (n=6)
      mg/L  SD  RSD
      2.19  0.10  4.6%
Table 2 lists the pH measured at each sampling interval of control and MRD-11 -027 test system
 Day  Control  MRD-11 -027
 7  4.52  3.40
 14  4.32  3.50
 21  4.31  3.46
 28  4.29  3.32

The test substance appeared to reach equilibrium after 21 days of slow-stir mixing. The mean water solubility calculated from the day 21 and day 28 replicates (n+6) is 2.19mg/L (RSD 4.6%). Triplicate sample analysis at each sampling interval all yielded RSDs less than 15% as required by the study protocol. Graphically depicts alpha pinene water solubility concentrations over time; again demonstrating equilibrium was reached within 21 days in the slow stir-system. No alpha pinene was dectected in any of the corresponding control samples.

Table 2 lists the pH measured at each sampling interval. The pH of the control system ranged from 4.29 to 4.52 and the pH of the test system ranged from 3.32 to 3.50. Acidic pH is expected as the gdH2O carrier has no buffering capacity.

Two related observations of the test system were made. A white precipitate formed and settled on the bottom of the test system vessel. Most of the precipitate formed in the first week of the study. No precipitate was observed in the control system. Also, while excess MRD-11 -027 was still observed on the surface of the test system over the course of the study, it appeared to be significantly less than the 100mg/L loading initially applied.

Alpha pinene is an alkene with a potentially reactive four member ring. It is possible that some of the solubilized alpha pinene reacted with the mercuric salt. Another possibility is that solubilization of alpha pinene sufficiently decreased the polarity of the test system water resulting in a precipitation of some of the mercuric chloride. The lower pH measured in the test system relative to the control system may also be related to the observed precipitation.

The water solubility of 2.19 mg/L measured at 20°C in this study is consistent with previously reported values for alpha pinene. The flavor and fragrance high production Volume Consortium cited a measured water solubility of 0.65mg/L at 25°C by Broderius at al and a calculated value of 1.09mg/L by Meylan. Fichan et al and Li and Perdue reported measured water solubilities at 25°C of 5mg/L and 2.49mg/L, respectively. The water solubility of alpha pinene at 20°C calculated by SPARC is 2.17mg/L.

Conclusions:
Interpretation of results (migrated information): slightly soluble (0.1-100 mg/L)
Test substance alpha-pinene appeared to reach equilibrium after 21 days of slow-stir mixing. The mean water solubility calculated from the day 21 and day 28 replicates (n=6) is 2.19 mg/L with relative standard deviation of 4.6%.
Executive summary:

A study was performed according to OECD 105 and OECD 123 guidelines, using a slow-stir mixing technique, in order to determine the water

solubility of test substance alpha-pinene.

Triplicate sample analysis were performed at 7, 14, 21 and 28 days. Standards and water solubility samples of alpha-pinene were analyzed by static headspace gas chromatography with flame ionization detection.

The pH has been measured at each sampling intervals for the test system control and test item alpha-pinene (MRD-11 -027).

Test item alpha-pinene appeared to reach equilibrium after 21 days of slow-stir mixing. The mean water solubility calculated from the day 21 and day 28 replicates n=6 is 2.19 mg/L with relative standard deviation of 4.6%.

The water solubility for alpha-pinene was determined to be 2.19 mg/L at 20°C in glass distilled water poisoned with 50 mg/L mercuric chloride.

This study was considered without restriction. No observations were made which might cause doubts concerning the validity of the study outcome.

Endpoint:
water solubility
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
α-Pinene is a bicyclic monounsaturated monoterpene and (-)-α-pinene is an enantiomeric form of α-pinene. Therefore, data on (-)-alpha pinene can be extrapolated to alpha-pinene. (see read-across justification document in section 13).
Reason / purpose:
read-across source
Water solubility:
ca. 2.3 mg/L
Temp.:
20 °C
pH:
>= 5 - <= 9.5
Remarks on result:
other: Measured pH : pH=5 at the beginning of the both experiment and pH=9.5 at the end of the both experiment. The relative difference between the results of the two experiments is 10.00%, less than 30% as required by the OECD 105 - elution column method.
Details on results:
Mean of two solubility values obtained in two different experiments.
Concentrations observed at 25 mL/h: mean of the five last samples = 2.18 mg/L (RSD = 9.77% : less than 30% as required by the OECD 105 - elution column method)
Concentrations observed at 12.5 mL/h: mean of the five last samples = 2.41 mg/L (RSD = 11.72 % : less than 30% as required by the OECD 105 - elution column method)

Preliminary test

The approximate solubility determined by the preliminary test was lower than 100 mg/L.

First experiment at a flow rate of 25 mL/h

The concentrations obtained as a function of time during this first experiment at 25 mL/h are presented in graph 1 : "Concentrations observed at 25 mL/h"

Measured pH :

-       at the beginning of the experiment : 5

-       at the end of the experiment : 9.5

The mean ± standard deviation of the five last samples is 2.18 ± 0.21 mg/L (RSD = 9.77% : less than 30% as required by the OECD 105 - elution column method).

 

The maximum difference observed in the five last samples is

           2.33 - 1.83 = 0.5 mg/L

 

The mean of these two maximum values is

           (2.33 + 1.83) / 2 = 2.08 mg/L

 

The relative difference, corresponding to the ratio of the maximum difference and the mean of the two maximum values is

           0.50 / 2.08 = 24.03%

 

Second experiment at a flow rate of 12.5 mL/h

The concentrations obtained as a function of time during this second experiment are presented in graph 2 : "Concentrations observed at 12.5 mL/h".

Measured pH :

-       at the beginning of the experiment : 5

-       at the end of the experiment : 9.5

 

The mean ± standard deviation of the five last samples is 2.41 ± 0.28 mg/L (RSD = 11.72% : less than 30% as required by the OECD 105 - elution column method)

 

The maximum difference observed in the five last samples is

           2.87 – 2.17 = 0.70 mg/L

 

The mean of these two maximum values is

           (2.87 + 2.17) / 2 = 2.52 mg/L

 

The relative difference, corresponding to the ratio of the maximum difference and the mean of the two maximum values is

0.70 / 2.52 = 27.77%

 

Conclusions:
Interpretation of results (migrated information): slightly soluble (0.1-100 mg/L)
The mean of the two solubility values obtained in the two different experiments is (2.18 + 2.41) / 2 = 2.30 mg/L
The relative difference between the results of the two experiments is (2.41 – 2.18) / 2.30 = 10.00%
The mean values obtained from two experiments did not differ by more than 30%, so these results are valid.
Executive summary:

The determination of Water solubility of (-)-alpha pinene was performed using the column elution method (OECD Guideline 105).

Due to the physicochemical properties of the test item (stability, volatility, adsorption on glass), the samples were analyzed as soon as possible after sampling. This precaution is crucial in order to avoid underestimation and variations of the measured concentrations.

Two independent experiments were carried out. The concentration of the substance was regularly measured by HPLC-UV (High Performance Liquid Chromatography with UV detector). The water solubility was recorded when the concentration reached a plateau.

The water solubility of (-)-alpha pinene obtained by the column elution method is 2.30 mg/L. This value is the mean of two independent measurements.

Endpoint:
water solubility
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
α-Pinene is a bicyclic monounsaturated monoterpene and (-)-α-pinene is an enantiomeric form of α-pinene. Therefore, data on (-)-alpha pinene can be extrapolated to alpha-pinene. (see read-across justification document in section 13).
Reason / purpose:
read-across source
Water solubility:
ca. 3.2 mg/L
Temp.:
20 °C
pH:
5
Remarks on result:
other: Mean of two solubility values obtained in two different experiments.
Details on results:
First experiment : mean of the five last samples = 2.92 mg/L (RSD = 2.94% : less than 15% as required by the OECD 105 - flask method)
Second experiment : mean of the five last samples = 3.47 mg/L (RSD = 10.14% : less than 15% as required by the OECD 105 - flask method)

Preliminary test

The approximate solubility determined by the preliminary test was lower 100 mg/L.

First experiment

The concentrations obtained as a function of time during this first experiment are presented in graph 1 : "Concentrations observed- first experiment"

Measured pH :

-       at the beginning of the experiment : 5

-       at the end of the experiment : 5

The mean ± standard deviation of the five last samples is 2.92 ± 0.08 mg/L (RSD = 2.94% : less than 15% as required by the OECD 105 - flask method)

 

The maximum difference observed in the five last samples is

           3.01 - 2.80 = 0.21 mg/L

 

The mean of these two maximum values is

           (3.01 + 2.80) / 2 = 2.91 mg/L

 

The relative difference, corresponding to the ratio of the maximum difference and the mean of the two maximum values is

           0.21 / 2.91 = 7.22 %

 

Second experiment

The concentrations obtained as a function of time during this second experiment are presented in graph 2 : "Concentrations observed- second experiment".

Measured pH :

-       at the beginning of the experiment : 5

-       at the end of the experiment : 5

 

The mean ± standard deviation of the five last samples is 3.47 ± 0.35 mg/L 3.47 (RSD = 10.14% : less than 15% as required by the OECD 105 - flask method)

 

The maximum difference observed in the five last samples is

           3.86 – 3.17 = 0.69 mg/L

 

The mean of these two maximum values is

           (3.86 + 3.17) / 2 = 3.52 mg/L

 

The relative difference, corresponding to the ratio of the maximum difference and the mean of the two maximum values is

0.69 / 3.52 = 19.60 %

 

Conclusions:
Interpretation of results (migrated information): slightly soluble (0.1-100 mg/L)
The mean of the two solubility values obtained in the two different experiments is (3.47 + 2.92) / 2 = 3.20 mg/L
The relative difference between the results of the two experiments is (3.47 – 2.92) / 3.20 = 17.19 %
Executive summary:

The determination of the water solubility of (-)-alpha pinene was performed using the slow stirring method adapted from OECD 123 guideline.

Due to the physicochemical properties of the test item (stability, volatility, adsorption on glass), the samples were analyzed as soon as possible after sampling. This precaution is crucial in order to avoid underestimation and variations of the measured concentrations.

Two independent experiments were carried out. The concentration of the substance was regularly measured by HPLC-UV (High Performance Liquid Chromatography with UV detector). The water solubility was recorded when the concentration reached a plateau.

The water solubility of (-)-alpha pinene obtained by the slow-stirring method is 3.20 mg/L.

This value is the mean of two independent measurements.

Description of key information

Water solubility of alpha-pinene: 2.19 mg/L at 20 °C

Water solubility of (-)-alpha-pinene: 2.75 mg/L at 20°C

Key value for chemical safety assessment

Water solubility:
2.19 mg/L
at the temperature of:
20 °C

Additional information

A study was performed to measure the water solubility of alpha-pinene with the slow-stirring method and according to OECD guideline 105 and 123. As the results was obtained under GLP without deviation, it was considered as valid and reliable without restriction. Therefore, the value used for the chemical safety assessment is 2.19 mg/L and is considered as key value. It is supported by consistent experimental data obtained with (-)-alpha-pinene.