Diethylammonium chloride

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because the substance has a low octanol water partition coefficient and the adsorption potential of this substance is related to this parameter

Description of key information

Low potential for adsorption based on low log Kow value (<3)

Key value for chemical safety assessment

Koc at 20 °C:

87.1

Additional information

Diethylammonium chloride (CAS 660-68-4) has a very low partitioning coefficient of -1.3 mg/L (at 20°C) and thus low potential for adsorption. In accordance with Column 2 of REACH Annex VIII, the adsorption/desorption screening test does not need to be conducted.

However, the adsorption potential of Diethylammonium chloride (CAS 660-68-4) was further investigated for the needs of the chemical safety assessment.

Diethylammonium chloride (CAS 660-68-4) is a dimethylamine hydrochloride salt, that dissociates rapidly in water to basic diethylammonium cation and chloride anions, which are highly mobile, their adsorption potential can be neglected. Considering the ionizing property of the basic diethylamine, the adsorption potential was calculated using Franco and Trapp ‘s expressions (2008) on estimation of the organic carbon-water partitioning coefficient of ionisable organic substances. The log Kow of 0.58, its pKa of 10.84 and 3 different pH values (4, 7, 9) were used as input parameters for the calculation.

The following equation was used for the Koc calculation as suggested by the authors:

Koc =Φn * 10^{0.37*logPn+1.70} +Φion * 10^{pKa^0.65*f^0.14}

 

Where:

Φn = 1/(1+10^(pH-pKa))

Pn: Kow of the neutral molecule (EpiWin)

pKa: 11.06 (more information in chapter 4.7)

Φion = 1-Φn

f: Ratio of concentration in octanol to total concentration: Kow (overall)/(Kow (overall) + 1)

 

The log Koc was calculated to be 1.84 at pH 4; 1.94 at pH 7 and 3.1 at pH 9. These values indicate that the adsorption potential of the substance to organic carbons in soil at neutral pH is low. According to the Guidance on Information Requirements and Chemical Safety Assessment, Chapter R.7.1.8.5 the log D value for the ionized molecule determined around the default pH of 7 is considered more relevant for chemical safety assessment. Therefore, the respective log Koc calculated at pH 7 has been used for the chemical safety assessment.

 

Reference:

Franco A. & Trapp S., 2008: Estimation of the soil-water partition coefficient normalized to organic carbon for ionizable organic chemicals. Environmental Toxicology and Chemistry, Vol. 27, No. 10, pp. 1995–2004.