Octadecan-1-ol, ethoxylated, phosphates

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1 October 2018 to 14 March 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

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))

Deviations:

no

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))

Deviations:

no

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

sewage sludge

Specific details on test material used for the study:

Purity: 100% (UVCB)
Appearance/Physical state: Solid, white pastille
Storage: Room temperature in the dark

Details on study design: HPLC method:

The sample, dead time and reference standard solutions were injected in duplicate using the following HPLC parameters:

HPLC System : Agilent Technologies 1200, incorporating workstation and autosampler
Detector types : variable wavelength (VW)
mass selective (MS)
Column : Agilent Eclipse XDB-CN 5 micro m (150 x 4.6 mm id)
Column temperature : 50 deg. C
Mobile phase : Methanol: purified water (550 mL:450 mL), adjusted to
pH 4.7 with 1 drop of formic acid, and then adjusted to
pH 5.7 with 0.1M sodium hydroxide
pH of mobile phase : 5.7
Flow-rate : 1.0 mL/min
Injection volume : 10 micro L
VW detector wavelength : 210 nm

MS detector parameters :
Interface : electrospray
Polarity : positive
Fragmentor voltage : 250 V
Mode and ion masses : Scan: 250 to 1000 m/z
Drying gas : 12 L/min at 350 deg. C
Nebulizer pressure : 50 psig
Capillary voltage : 5000 V

Key result

Sample No.:

#1

Type:

Koc

Remarks on result:

other: The adsorption coefficient of the test item has been determined to be in the range less than 17.8 to greater than 4.27 E5.

Key result

Sample No.:

#1

Type:

log Koc

Remarks on result:

other: The log10 Koc is in the range less than 1.25 to greater than 5.63.

Details on results (HPLC method):

The adsorption coefficient of the test item has been determined to be in the range less than 17.8 to greater than 4.27 E5, corresponding to a log10 Koc in the range less than 1.25 to greater than 5.63.

Using area normalization, the majority of the test item (approximately 86%) indicated a log10 Koc of greater than 5.63. This would classify the test item as being essentially immobile in soil.

According to the method guidelines, “for ionizable substances, two tests should be performed with both ionized and non-ionized forms … but only in cases where at least 10% of the test compound will be dissociated within pH 5.5 to pH 7.5”. The test item has predicted dissociation constants of approximately 0.9 and 3.6. Therefore, testing was performed at pH 5.7 to evaluate the test item in its environmentally relevant form, i.e. in its ionized form. As the slope of the calibration curve for the reference standards showed good first order correlation and as the retention times between duplicate injections for each solution was consistent, the HPLC method was considered valid for the determination of adsorption coefficient.

The retention times, capacity factor and log10 Koc value determined for the sample are shown in the following table:

Peak	Injection	Retention Time (min)	Capacity Factor (k')	Log10k'	Log10Koc	Mean Log10Koc	Mean Area %
1	1	1.211	<0.201	<-0.697	<1.25	<1.25	2.0
	2	1.213	<0.201	<-0.697	<1.25
2	1	1.486	<0.201	<-0.697	<1.25	<1.25	1.2
	2	1.538	<0.201	<-0.697	<1.25
3	1	1.689	<0.201	<-0.697	<1.25	<1.25	3.4
	2	1.687	<0.201	<-0.697	<1.25
4	1	2.050	0.234	-0.630	1.06	1.02	3.3
	2	2.027	0.220	-0.657	0.970
5	1	4.152	1.500	0.176	3.86	3.83	2.0
	2	4.065	1.447	0.161	3.80
6	1	8.112	3.884	0.589	>5.63	>5.63	0.6
	2	8.049	3.846	0.585	>5.63
7	1	12.388	6.458	0.810	>5.63	>5.63	85.2
	2	12.222	6.358	0.803	>5.63

Overall log₁₀K_oc:                             In the range <1.25 to >5.63
Overall adsorption coefficient:          In the range <17.8 to > 4.27 x 10⁵

Validity criteria fulfilled:

yes

Conclusions:

In a study conducted according to OECD 121, using the HPLC method, the adsorption coefficient of the test item has been determined to be in the range less than
17.8 to greater than 4.27 E5, corresponding to a log10 Koc in the range less than 1.25 to greater than 5.63.

Using area normalization, the majority of the test item (approximately 86%) indicated a log10 Koc of greater than 5.63.

This would classify the test item as being essentially immobile in soil.

Executive summary:

The adsorption coefficient of the test item has been determined to be in the range less than 17.8 to greater than 4.27 E5 , log10 Koc in the range less than 1.25 to greater than 5.63, at pH 5.7, using the HPLC screening method, designed to be compatible with Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008, and OECD Guidelines for Testing of Chemicals No. 121, 22 January 2001.

Using area normalization, the majority of the test item (approximately 86%) indicated a log10 Koc of greater than 5.63 at pH 5.7.

This would classify the test item as being essentially immobile in soil.

Description of key information

In a study conducted according to OECD 121, using the HPLC method, the adsorption coefficient of the test item has been determined to be in the range less than 17.8 to greater than 4.27 E5, corresponding to a log10 Koc in the range less than 1.25 to greater than 5.63.

Using area normalization, the majority of the test item (approximately 86%) indicated a log10 Koc of greater than 5.63.

This would classify the test item as being essentially immobile in soil.