Nickel bis(2-ethylhexanoate)

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Test temperature:

During the study, a column thermostat was used, as shown in the list of devices (L-7360 Column Oven). This thermostat was set to 25 °C. Since this is a calibrated instrument therefore it was not necessary to register the temperature.

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: Merck-Hitachi LaChrom HPLC system
- Type, material and dimension of analytical (guard) column: LiChrospher 100 CN 250 x 4 mm, 5µm
- Detection system: L-7400 UV Detector, at 210 nm

MOBILE PHASES
- Type: Methanol : 0.1 M phosphate buffer pH:3.0 = 3 : 7

DETERMINATION OF DEAD TIME
- Method: Dead time, t0 was determined by the injection of sodium nitrate solution.

Seven chemicals (reference test items) for which log Koc has been reported were used to calibrate the elution time in units of log Koc:
Acetanilide, Methyl benzoate, Isoproturon, Linuron, Naphthalene, Fenthion, Pyrazophos

DETERMINATION OF RETENTION TIMES
Three series of the reference solutions and the test item solution were measured alternately, with two replicate injections.

EVALUATION
- Calculation of capacity factors k':
k' = (tR - t0) / t0
A calibration plot of log k' versus log Koc was prepared. The calibration equation was determined by linear regression using the least squares method.

- Calculation of retention times:
- Determination of the log Koc value:

Type:

log Koc

Value:

2.17

Temp.:

25 °C

Details on results (HPLC method):

- Retention times of reference substances used for calibration: see tables
- Graph of regression line attached: see document attached
- Details of fitted regression line (log k' vs. log Koc):
The equation of the curve fitted to the calibration points is as follows:
log k' = 0.609 × log Koc - 0.784 (Rsq = 0.967)

- Average retention data for test substance:
Retention time for test substance = 7.42 min;
The capacity factors k’ and log Koc for Nickel 2-ethylhexanoate were calculated based on the calibration data obtained with the reference substances.
The estimated log Koc 2.17.
The estimated Koc 147.

Tables:

Chemical name	log KOC	Retention time (min)	log k'		log Koc		Accuracy log unit	Repeatability DlogKOC, log unit
	from OECD 121		Calculated		Calculated
Sodium nitrate	-	1.67	for determination of dead time
		1.67
		1.67
		1.67
		1.67
		1.67
	Mean	1.67
	CV%	0.0
Acetanilide	1.25	3.10	-0.067	1.18		0.09		0.03
		3.10	-0.067	1.18
		3.06	-0.080	1.15
		3.06	-0.080	1.15
		3.05	-0.083	1.15
		3.06	-0.080	1.15
	Mean	3.07	-0.076	1.16
	CV%	0.7	-	-
Methyl-benzoate	1.80	4.96	0.294	1.77		0.05		0.03
		4.96	0.294	1.77
		4.85	0.280	1.74
		4.85	0.280	1.74
		4.82	0.276	1.74
		4.83	0.277	1.74
	Mean	4.88	0.283	1.75
	CV%	1.3	-	-
Isoproturon	1.86	6.45	0.457	2.04		0.16		0.03
		6.44	0.456	2.03
		6.29	0.442	2.01
		6.29	0.442	2.01
		6.24	0.437	2.00
		6.24	0.437	2.00
	Mean	6.33	0.445	2.02
	CV%	1.5	-	-

Chemical name	log KOC	Retention time (min)	log k'	log Koc	Accuracy log unit	Repeatability DlogKOC, log unit
	from OECD 121		Calculated	Calculated
Linuron	2.59	12.48	0.811	2.62	0.01	0.03
		12.44	0.809	2.61
		12.11	0.796	2.59
		12.11	0.796	2.59
		12.00	0.791	2.58
		12.01	0.792	2.58
	Mean	12.19	0.799	2.60
	CV%	1.8	-	-
Naphthalene	2.75	13.55	0.852	2.68	0.08	0.02
		13.53	0.851	2.68
		13.25	0.841	2.67
		13.25	0.841	2.67
		13.15	0.837	2.66
		13.17	0.838	2.66
	Mean	13.32	0.843	2.67
	CV%	1.3	-	-
Fenthion	3.31	44.49	1.409	3.60	0.26	0.04
		44.24	1.406	3.59
		43.04	1.394	3.57
		43.01	1.394	3.57
		42.16	1.385	3.56
		42.07	1.384	3.56
	Mean	43.17	1.395	3.57
	CV%	2.4	-	-
Pyrazophos	3.65	36.95	1.325	3.46	0.21	0.04
		36.72	1.322	3.45
		36.05	1.314	3.44
		35.95	1.312	3.44
		35.27	1.304	3.42
		35.21	1.303	3.42
	Mean	36.03	1.313	3.44
	CV%	2.0	-	-
Nickel 2-ethylhexanoate	-	7.46	0.540	2.17	-	0.01
		7.45	0.539	2.17
		7.43	0.538	2.17
		7.41	0.536	2.17
		7.38	0.534	2.16
		7.37	0.533	2.16
	Mean	7.42	0.537	2.17
	CV%	0.5	-	-

Validity criteria fulfilled:

yes

Conclusions:

The estimated log Koc 2.17.
The estimated Koc 147.

Description of key information

An lab test was performed according to the OECD guideline 121 on the test substance, Nickel 2-ethylhexanoate.
Different studies, in compliance with OECD guideline n°106 adsorption/desorption using a batch equilibrium method were presented. Many types of soils, sediment and water were studied and their characteristics were identified (pH, organic matter, DOC, Al, Fe, clay content...). Koc and other adsorption coefficients (Kp) were identified.