Amines, N-(C16-18 and C18-unsatd. alkyl)-N,N',N'-trimethyltrimethylenedi-

Endpoint summary

Description of key information

A mean Kd for soil was observed of 1763 L/kg based on a refined sorption/desorption test in agreement with OECD 106 test using three different soils.

Additional information

N-C16 -18 -alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3 -diamine has pKa's of 10.8, 9.7 and 7.2, which means that the amines are for the main fraction protonated under ambient conditions. As a consequence this molecule will sorb strongly to negatively charged surfaces like glassware, soil and sediment constituents.

In the sorbent N-C16 -18 -alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3 -diamine can adsorb both onto the organic fraction and onto the surface of the mineral phase, where sodium and potassium ions can be exchanged against the alkyl ammonium ion. The determination of a Koc from log Kow is not opportune, because the common equations for Koc derivation are not valid for both ionic and surface active substances.

An adsorption/desorption study with N-C16 -18 -alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3 –diamine was performed according to OECD 106 using three soils with different organic carbon content and CEC value. The mean distribution constants for the three main constituents i.e. the C16, C18 and C18 unsaturatedalkyl trimethylpropane-1,3 –diamine are respectively 2029, 2042 and 1219 L/kg. 

The mean distribution constant for the three soils for with N-C16 -18 -alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3 –diamine were found torange from 482 to 3302 L/kg. There seems to be no relationship between the organic carbon content of the soils and the measured distribution coefficients. The observed distribution coefficients seem to increase with the clay content and CEC of the soils.

Results of the three tested soils

Soil	Clay (%)	Silt (%)	Sand (%)	CEC (meq/100g)	pH	Org C (%)	Caq (µg/L)	Kd (cm^3/g)	Koc (cm^3/g)
LUFA 2.2	7.8	14.0	78.3	6.0	6.7	1.6	542	482	30131
LUFA 2.3	9.8	29.3	61.0	5.4	6.7	0.617	188	1506	244143
LUFA 2.4	27.5	44.2	28.3	26.0	7.5	2.07	99.3	3302	159519

Because there is no principal difference between soil and sediments considering the sorption properties and because for cationic surfactants the degree of sorption is not related to the organic carbon content, the value as observed for soil will also be used for sediment and suspended particles. For activated sludge which consists mainly of organic matter the sorption data as observed for soil are not considered to be representative. This is however not a serious problem because the removal by sorption in a waste water treatment plant will be close to what is predicted in the waste water treatment simulation test i.e. 4.3% removal. In the table below, the distribution constants used in this assessment are summarized:

 

Table: Distribution constants for N-C16 -18 -alkyl-(evennumbered, C18 unsaturated) trimethylpropane-1,3–diamine

Kpsoil	1763 L/kg	Ksoil-water	2645 m^3/m^3
Kpsusp	3526 L/kg	Ksusp-water	882 m^3/m^3
Kpsed	1763 L/kg	Ksed-water	882 m3/m^3

With a Kp_suspof 3526 L/kg and a concentration of 15 mg/L suspended matter in surface waters, the adsorbed fraction is calculated as 5%.