2-methylpentane-1,5-diamine

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption, other

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For details on endpoint specific justification please see read-across report in section 13 or find a link in cross-reference “assessment report”.

Reason / purpose for cross-reference:

assessment report

Reason / purpose for cross-reference:

read-across source

Media:

other:

Type:

Kd

Remarks:

#1

Value:

14

Temp.:

20 °C

Remarks on result:

other: L/kg

Type:

Kd

Remarks:

#2

Value:

714

Temp.:

20 °C

Remarks on result:

other: L/kg

Type:

Kd

Remarks:

#3

Value:

490

Temp.:

20 °C

Remarks on result:

other: L/kg

Type:

Kd

Remarks:

#4

Value:

134

Temp.:

20 °C

Remarks on result:

other: L/kg

Type:

Kd

Remarks:

#5

Value:

152

Temp.:

20 °C

Remarks on result:

other: L/kg

Adsorption and desorption constants:

See "any other information on results incl. tables", table 1

Concentration of test substance at end of adsorption equilibration period:

Please see table 2, section "Any other information on results including tables"!

Transformation products:

no

Details on results (Batch equilibrium method):

Results on read-across source substance HMD are directly applicable to target substance MPMD: Independently of molecular weight (which indeed is identical), for calculation of the distribution coefficient Kd, the ratio of (1) the amount of the substance adsorbed on the soil at adsorption equilibrium (µg/g) and (2) the mass concentration of the substance in the aqueous phase at adsorption equilibrium (µg/cm^3) is decisive.

Table 1: Determined adsorption constants for source substance HMD:

Parameter	Unit	Soil I	Soil II	Soil III	Soil IV	Soil V
Kd_ads	[mL/g]	14	714	490	134	152
Koc_ads	[mL/g]	2‘023	43‘004	12‘164	11‘253	14‘754

While Koc-values are given, calculated adsorption and desorption distribution coefficients were independent of the organic carbon content. Therefore, any environmental fate assessment should preferably be based on Kd_ads or Kd_des values.

 

Table 2: Kinetics test: Distribution of source substance HMD between the aqueous phase and soil after 48 hours of adsorption at the soil/solution ratio of 4/100 or 1/100. Each sample contained 179 µg HMD

Soil	Sample	Ratio	m	Vo	m(ads)s	m(ads)aq	Kd_ ads	Kd· ratio	KOC_ ads
			[g]	[mL]	[µg]	[µg]	[mL/g]		[mL/g]
Soil I Speyer 2.1	Sample A	4:100	4	100	60.65	118.22	13	1	1'894
	Sample B		4	100	65.85	113.02	15	1	2'151
	Mean				63.25	115.62	14	1	2'023
Soil II Speyer 6S	Sample A	1:100	1	100	156.17	22.70	716	7	43'145
	Sample B		1	100	156.04	22.83	712	7	42'863
	Mean				156.10	22.76	714	7	43'004
Soil III Empingham	Sample A	1:100	1	100	147.95	30.91	486	5	12'070
	Sample B		1	100	148.34	30.52	494	5	12'257
	Mean				148.15	30.72	490	5	12'164
Soil IV Mechtildshausen	Sample A	1:100	1	100	100.35	78.52	134	1	11'255
	Sample B		1	100	100.33	78.54	134	1	11'250
	Mean				100.34	78.53	134	1	11'253
Soil V River Sediment	Sample A	1:100	1	100	104.19	74.68	141	1	13'657
	Sample B		1	100	110.58	68.29	163	2	15'852
	Mean				107.39	71.48	152	2	14'754

 

Table 3: Stability of read-across source substance HMD in 0.01 M CaCl2 solution during the experiment at an initial test item concentration of about 1.8 mg/L

 

Control % of initial	Adsorption time (hours)
	2		5	24		48	52		72	96	168
Glas
Sample A	102.5		92.4	100.6		97.3	101.2		95.2	92.2	104.7
Sample B	98.2		99.6	98.9		97.2	94.3		98.2	98.7	101.1
Mean	100.4		96.0	99.8		97.2	97.8		96.7	95.5	102.9

Validity criteria fulfilled:

yes

Conclusions:

A Batch Equilibrium test (according to OECD 106, compliant to GLP; 2013) was performed using the following soil and sediment types:
Speyer 2.1 (soil I, sand), Speyer 6S (soil II, clay), Empingham (soil III, clay loam), Mechtildshausen (soil IV, loam) and sediment of the River Rhine (soil V, sandy loam).
The following results were obtained for the source substance 1,6-hexane diamine (HMD; CAS No. 124-09-4):
Sorption was strongest to the clay soil (soil II) and weakest to the sand soil (soil I). With the exception of the river sediment (Soil V), sorption increased with increasing clay content. No correlation of sorption and the soil properties pH value, cation exchange capacity and organic carbon content was observed. The sorbed fraction of analyte increased with the amount of soil used in the batch systems. Apparent equilibrium distribution was reached within 48h. Accordingly, the adsorption coefficients (Kd) were calculated after 48h of adsorption:

Kd range soil: 14 (soil I) to 714 (soil II) L/kg; average Kd: 338 L/kg (log Kd: 2.53); corresponding to average log Koc = 4.23 (based on a default OC content of soil of 2% according to ECHA guidance document R.16);
Kd sediment: Kd = 152 L/kg (log Kd: 2.18); corresponding to log Koc = 3.18 (based on a default OC content of suspended matter of 10% according to ECHA guidance document R.16);

The calculated adsorption and desorption distribution coefficients were independent of the organic carbon content. Therefore, any environmental fate assessment should preferably be based on Kd_ads values.

Executive summary:

The study used as source investigated the distribution coefficients for adsorption (Kd) for four soils and one sediment according to OECD TG 106 (Batch Equilibrium Test; 2000).

The study results of the source compound were considered applicable to the target compound. No adaption of results obtained on the source substance to the target substance were required: independently of molecular weight (which indeed is identical), for calculation of the distribution coefficient Kd, the ratio of (1) the amount of the substance adsorbed on the soil at adsorption equilibrium (µg/g) and (2) the mass concentration of the substance in the aqueous phase at adsorption equilibrium (µg/cm^3) is decisive. The Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in section 13 or find a link in cross-reference “assessment report”.

Description of key information

A Batch Equilibrium test (according to OECD 106, compliant to GLP; 2013) was performed using the following soil and sediment types:
Speyer 2.1 (soil I, sand), Speyer 6S (soil II, clay), Empingham (soil III, clay loam), Mechtildshausen (soil IV, loam) and sediment of the River Rhine (soil V, sandy loam).
The following results were obtained for the source substance 1,6-hexane diamine (HMD; CAS No. 124-09-4):
Sorption was strongest to the clay soil (soil II) and weakest to the sand soil (soil I). With the exception of the river sediment (Soil V), sorption increased with increasing clay content. No correlation of sorption and the soil properties pH value, cation exchange capacity and organic carbon content was observed. The sorbed fraction of analyte increased with the amount of soil used in the batch systems. Apparent equilibrium distribution was reached within 48h. Accordingly, the adsorption coefficients (Kd) were calculated after 48h of adsorption:

Kd range soil: 14 (soil I) to 714 (soil II) L/kg; average Kd: 338 L/kg (log Kd: 2.53); corresponding to average log Koc = 4.23 (based on a default OC content of soil of 2% according to ECHA guidance document R.16);
Kd sediment: Kd = 152 L/kg (log Kd: 2.18); corresponding to log Koc = 3.18 (based on a default OC content of suspended matter of 10% according to ECHA guidance document R.16);

The calculated adsorption and desorption distribution coefficients were independent of the organic carbon content. Therefore, any environmental fate assessment should preferably be based on Kd_ads values.

Key value for chemical safety assessment

Other adsorption coefficients

Type:

log Kp (solids-water in effluent sewage sludge)

Value in L/kg:

2.18

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in activated sewage sludge)

Value in L/kg:

2.18

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in settled sewage sludge)

Value in L/kg:

2.18

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in raw sewage sludge)

Value in L/kg:

2.18

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in suspended matter)

Value in L/kg:

2.18

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in soil)

Value in L/kg:

2.53

at the temperature of:

20 °C

Other adsorption coefficients

Type:

log Kp (solids-water in sediment)

Value in L/kg:

2.18

at the temperature of:

20 °C

Additional information

The study used as source investigated the distribution coefficients for adsorption (Kd) for four soils and one sediment according to OECD TG 106 (Batch Equilibrium Test; 2000). The following results were obtained:

Para-meter	Unit	Soil I	Soil II		Soil III	Soil IV	Sed (soil V)
Kd	[mL/g]	14	714		490	134	152

 

The following values are used for risk assessment:

Soil: (arithmetic mean over all four soils) Kd: 338 L/kg (log Kd: 2.53);

Sediment: Kd = 152 L/kg (log Kd: 2.18).

Indicative Koc values can be calculated from the Kd values, following Gustafson (1989; Groundwater ubiquity score: A simple method for assessing pesticide leachability; Environmental Toxicology and Chemistry, 8, 339-357): mean Kd for soil is divided by the generic organic carbon content of European soils as given in REACH guidance R. 16 (weight fraction organic carbon in soil solids = 2%). Proceeding the same way for sediment (division of Kd by generic weight fraction organic carbon in suspended matter of 10% as given in R.16 - for local assessment of sediment suspended matter is used instead of sediment according to R.16 and EUSES / ECETOC TRA), the following indicative log Koc value can be derived from the Kd value:

 

Soil (average):  log Koc = 4.23;

Sediment:         log Koc = 3.18.

 

The study results of the source compound were considered applicable to the target compound. No adaption of results obtained on the source substance to the target substance were required: independently of molecular weight (which indeed is identical), for calculation of the distribution coefficient Kd, the ratio of (1) the amount of the substance adsorbed on the soil at adsorption equilibrium (µg/g) and (2) the mass concentration of the substance in the aqueous phase at adsorption equilibrium (µg/cm^3) is decisive. The Justification and applicability of the read-across approach (structural analogue) is outlined in the read-across report in IUCLID section 13.