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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:

Experimental Phase: 09 March 2018 to 14 March 2018. Report Issue: 16 July 2018.

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:

yes

Remarks:

The batch used to perform the test was diffferent from that stated in the study plan. This deviation was considered to have had no impact on the integrity of the study.

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:

yes

Remarks:

The batch used to perform the test was diffferent from that stated in the study plan. This deviation was considered to have had no impact on the integrity of the study.

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

other: HPLC column containing lipophilic and polar moieties.

Details on study design: HPLC method:

EQUIPMENT
HPLC system : Agilent Technologies 1100 Series
Column : XSelect CN 5μm (150 x 4.6 mm id)
Column temperature : 30 degrees C
Flow rate : 1 ml/min
Injection volume : 10ul
VW detector wavelength: 210 nm

MOBILE PHASES
- Mobile phase A: Methanol
-Mobile phase B: purified water (ph 5.5)

SAMPLE SOLUTIONS
- Test item (1.0111 g) was diluted to 100 mL with methanol, to give a concentration of 10.1 g/L.

DETERMINATION OF DEAD TIME
- Method: The dead time was determined by measuring the retention time of formamide (purity* 99.6%) of a 727 mg/L solution in methanol: purified water (55:45 v/v).

REFERENCE SUBSTANCES
- Identity: Acetanilide, Phenol, Atrazine, Triadimenol, Linuron, Naphthalene, Endosulfan-diol, Fenthion, α-Endosufan, Phenanthrene, Diclofop-methyl, DDT

DETERMINATION OF RETENTION TIMES
- The sample, dead time and reference standard solutions were injected in duplicate using the HPLC parameters given above.

REPETITIONS
- Number of determinations: duplicate

Key result

Type:

Koc

Value:

> 5 000 dimensionless

Key result

Type:

log Koc

Value:

> 3.7 dimensionless

Details on results (HPLC method):

The adsorption coefficient of the test item was determined to be in the range < 17.8 to > 4.27 x 10^5, log10 Koc in the range < 1.25 to > 5.63.

DISCUSSION

As the test item had a high affinity for the stationary phase of the column, the mobile phase was adjusted to 100% methanol after the retention time of DDT to elute the sample. The test item was considered to contain no modes of dissociation. Therefore, the test was performed at approximately neutral pH, with the test item in a non-ionised 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. Based on the chromatographic data, the test item was considered to be stable during the test procedure.

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient of the test item has been determined to be in the range < 17.8 to > 4.27 x 105, log10 Koc in the range < 1.25 to > 5.63. Based on the area percent values, the majority of test item constituents will have a mobility classification of immobile (>98% of the test item, log Koc >3.7, Koc >5000).

Executive summary:

Introduction

The Adsorption coefficient of the test substance was determined using a HPLC screening method, designed to be compatible with the following methods:

 

1) Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001

2) Method C.19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008

 

Method

The test system utilised high performance liquid chromatography. A commercially available cyanopropyl reverse phase HPLC column containing lipophilic and polar moieties was used.

 

Conclusion

The adsorption coefficient of the test item has been determined to be in the range < 17.8 to > 4.27 x 105, log10 Koc in the range < 1.25 to > 5.63. Based on the area percent values, the majority of test item constituents will have a mobility classification of immobile (>98% of the test item, log Koc >3.7, Koc >5000).

Description of key information

Adsorption coefficient of the test substance.

Key value for chemical safety assessment

Koc at 20 °C:

5 000

Additional information

The adsorption coefficient of the test item has been determined to be in the range < 17.8 to > 4.27 x 105, log10 Koc in the range < 1.25 to > 5.63. Based on the area percent values, the majority of test item constituents will have a mobility classification of immobile (>98% of the test item, log Koc >3.7, Koc >5000).