Oleic acid, compound with (Z)-N-octadec-9-enylpropane-1,3-diamine (2:1)

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-05-25 -> 2011-06-16

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

See the "principles of method if other than guidelines" section

Principles of method if other than guideline:

Because of the low water solubility and suspicion that the tested substance may for micelles, a slow-stirring method has been used with some resemblance to the slow-stirring method for determination of the partition coefficient in OECD Guideline no 123.
1.0 L of ultra pure water was added to each of the three test vessels. 5 grams of heated test substance was added on the top from a glass tube. The test substance cooled to room temperature and became very viscous within seconds. The vessels were stirred at 150 rpm. Saturation of the substance in water was started in a temperature conditioned room. Sampling was performed at 7, 14 and 21 days after start of saturation to ensure that equilibrium has been reached.

1. The slow-stir method
A slow-stirring method has been used with some resemblance to the slow-stirring method for determination of the partition coefficient in OECD Guideline no 123. This method has also been used by J Jackson Ellington (J. Chem. Eng. Data 1999 (44) 1414-1418) and Letinski et al (Chemosphere 2002 (48) 257-265). It was concluded from these references that an equilibrium time of 7-8 days should be sufficient. 1.0 L of ultra pure water was added to each of the three test vessels. The test substance was heated to 50 °C in order to make it more fluid. 5 grams of heated test substance was added on the top from a glass tube. The test substance cooled to room temperature and became very viscous within seconds. The vessels were stirred at 150 rpm. Saturation of the substance in water was started on Day 0 in a temperature conditioned room. Sampling was performed at 7, 14 and 21 days after start of saturation. The temperature during sampling was between 19.4 and 20.1 °C. Before the first two samplings the stirring was paused for one hour and the last sampling was done after a 24 hour pause of slow stir. First about 10 mL was taken to waste and thereafter about 2 mL of the water solution was transferred to glass tube containing 2 ml leaching solution with double internal standard concentration.

2. The LCMS method
There is a slight excess of the oleic acid (0.5%) in the test substance. Hence it is assumed that all amine is present as oleate salt. It is also assumed that the substance is present as the oleate salt in the water either fully dissociated or as a complex but in the same proportions as in the pure substance in order to keep the water solution electro-neutral. Analytical Center method 11 AM 0021-01, “Determination of oleic acid, compound with (Z)-Noctadec-9-enylpropane-1,3-diamine in water by LCMS was used for quantification.
The following conditions were used: The carbon chain distribution of “oleyl” was: C12 1%, C14 3%, C16 4%, C18’ 74%, C18’’ 8%, C18’’’ 2%, C18 2%.
Primary amine by-products are neglected. They are probably less water soluble. The calibration curve is made from the weight of the dioleate salt. Hence, each measured diamine homologue was calibrated against the corresponding dioleate salt. The water solubility value was calculated as the sum of the saturation concentration of the ingoing homologues of the product. The average value from triplicate sample times and triplicate samples (9 samplings) is reported

GLP compliance:

no

Type of method:

other: slow-stir method

Key result

Water solubility:

ca. 0.005 mg/L

Conc. based on:

test mat. (dissolved fraction)

Temp.:

20 °C

pH:

ca. 7

Details on results:

The individual flask concentrations (average of duplicate LCMS runs) are shown in Table 1. The average saturation concentration of N-oleyl-1,3-diaminopropane dioleate in water is presented in Table 2. The water solubility of the substance is around 0.005 mg/L.

Validity of data
The water was clear upon visual inspection at each sampling occasion both before and after stop of stirring. Although the water solution contained very low concentrations there was a trend of increasing concentration the longer the equilibration time. For practical reasons the experiment was stopped after 21 days. The high viscosity of the substance and its high hydrophobicity make the equilibration slower than for a smaller molecule in a more fluid state. Logically the shorter alkyl homologues as C12 and C14 should be more water soluble than the longer chains and this was also observed. The concentration of the C12 homologue is roughly the same throughout the experiment. Possibly the time for equilibration is faster for the shorter chain alkyl. The apparent dissolution of one homologue is probably influenced by the apparent solubilities of all the other homologues. The water concentration of one homologue will probably be different when testing the solubility of a commercial mixture compared to testing the pure homologue.

Table 1. Table of the homologue concentrations of N-oleyl-1,3-diaminopropane dioleate (presented as the concentrations of the dioleate salt).

Sample name	Incubation time (day)	C12 Conc. (µg/L)	C14 Conc. (µg/L)	C16 Conc. (µg/L)	C18' Conc. (µg/L)	C18'' Conc. (µg/L)	C18''' Conc. (µg/L)	C18 Conc. (µg/L)	Sum conc. (lower limit)	Sum conc. (upper limit)
Blank		<0.3	<0.2	<0.1	<0.2	<0.2	<0.4	<0.1	0	1.5
FLASK A	7	1.35	<0.2	<0.1	<0.2	<0.2	<0.4	<0.1	1.35	2.55
FLASK B	7	2.20	0.66	0.10	0.26	<0.2	<0.4	<0.1	3.22	3.92
FLASK C	7	0.53	<0.2	<0.1	<0.2	<0.2	1.29	<0.1	1.82	2.62
FLASK A	14	0.81	0.31	0.25	0.21	0.52	4.10	0.17	6.37	6.37
FLASK B	14	0.59	<0.2	<0.1	<0.2	<0.2	0.66	<0.1	1.25	2.05
FLASK C	14	0.33	0.27	0.26	0.27	0.46	4.02	0.18	5.80	5.80
FLASK A	21	0.95	0.61	0.57	0.36	0.88	8.26	0.34	11.97	11.97
FLASK B	21	1.42	0.22	0.18	0.21	0.35	2.35	0.11	4.84	4.84
FLASK C	21	0.99	0.25	0.32	0.28	0.69	6.08	0.28	8.89	8.89
Total average lower limit		1.02	0.26	0.19	0.18	0.32	2.97	0.12	5.06	-------
Total average upper limit		1.02	0.33	0.22	0.24	0.41	3.06	0.17	-------	5.44
Standard deviation									3.6	3.4
Limit of quantification		0.3	0.2	0.1	0.2	0.2	0.4	0.1

Table 2. The water solubility of the different homologues of oleic acid, compound with (Z)-N-octadec-9-enylpropane-1,3-diamine (averaged values of triplicate flasks and triplicate sampling occaisions 7, 14 and 21 days after starting the test). The solubility of oleyldiamine dioleate is presented as the sum of the solubilities of its homologues.

Constituent name	Water solubility contributions (mg/L)
Dodecyl-1,3-diaminopropane dioleate	0,001
Tetradecyl-1,3-diaminopropane dioleate	= 0,0007
Hexadecyl-1,3-diaminopropane dioleate	= 0,0006
Octadecatrienyl-1,3-diaminopropane dioleate	= 0,0004
Octadecadienyl-1,3-diaminopropane dioleate	= 0,0009
Octadecenyl-1,3-diaminopropane dioleate	= 0,008
Octadecyl-1,3-diaminopropane dioleate	= 0,0003

Conclusions:

The water solubility of the substance is around 0.005 mg/L.

Executive summary:

A slow-stirring method has been used with some resemblance to the slow-stirring method for determination of the partition coefficient in OECD Guideline no 123. This method has also been used by J Jackson Ellington (J. Chem. Eng. Data 1999 (44) 1414-1418) and Letinski et al (Chemosphere 2002 (48) 257-265). It was concluded from these references that an equilibrium time of 7-8 days should be sufficient. 1.0 L of ultra pure water was added to each of the three test vessels. The test substance was heated to 50 °C in order to make it more fluid. 5 grams of heated test substance was added on the top from a glass tube. The test substance cooled to room temperature and became very viscous within seconds. The vessels were stirred at 150 rpm. Saturation of the substance in water was started on Day 0 in a temperature conditioned room. Sampling was performed at 7, 14 and 21 days after start of saturation. The temperature during sampling was between 19.4 and 20.1 °C. Before the first two samplings the stirring was paused for one hour and the last sampling was done after a 24 hour pause of slow stir. First about 10 mL was taken to waste and thereafter about 2 mL of the water solution was transferred to glass tube containing 2 mL leaching solution with double internal standard concentration. Concentrations were analyzed by HPLC/MS. The calibration curve is made from the weight of the dioleate salt. Hence, each measured diamine homologue was calibrated against the corresponding dioleate salt. The water solubility value was calculated as the sum of the saturation concentration of the ingoing homologues of the product. The average value from triplicate sample times and triplicate samples (9 samplings) is reported. The water solubility is around 0.005 mg/L (sum of all homologues)

.

Description of key information

The water solubility of the substance was determined according following OECD 105/123 TG (OECD 105, slow-stirring method). The water solubility of the substance is around 0.005 mg/L.

Key value for chemical safety assessment

Water solubility:

0.005 mg/L

at the temperature of:

20 °C