Lithium bis(oxalato)borate

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:

2010-08-18 to 2010-10-08

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP and guideline compliant 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

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Test temperature:

26 °C, 90 % humidity

Details on study design: HPLC method:

EQUIPMENT
- Apparatus: HPLC Agilent
- Type: 1200
- Type, material and dimension of analytical (guard) column: Agilent TC-C18 (4.6 mm, 250 mm, 5 µm)
- Detection system: variable wavelength detector (VWD, 230 nm)

MOBILE PHASES
- Type: water/acetonitrile (35 % / 65 %)
- Solutes for dissolving test and reference substances: 0.1 g of the test substance are solved in 30 mL THF and then scaled with purity water to 100 mL resulting in a solution of 1 mg/mL concentration.

DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column. Sodium nitrate was used to detect the dead time of the column.

REFERENCE SUBSTANCES
- Identity (CAS Number): Sodium nitrate (7633-99-4), Acetanilide (103-84-4), Phenol (108-95-2), Methyl benzoate (93-58-3), Naphthalene (91-20-3), Phenanthrene (85-01-8), DDT (50-29-3)

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 10 µg/mL with 10 µL injection volume
- Quantity of reference substances: same as test substance
- Intervals of calibration: no data

REPETITIONS
- Number of determinations: no data

EVALUATION
- Calculation of capacity factors k': were calculated from the retention times (tR) of the selected reference substances and the test material and the dead time (t0) using the following relation:

K´= (tR - t0) / t0

- Calculation of retention times: were not calculated but measured with HPLC.
- Determination of the log Koc value: The adsorption coefficient (Koc) is deduced from the capacity factor (K´) using a calibration plot of log K´ versus log Koc of the reference substances. The regression coefficients were determined by linear regression calculation using the least squares method:

log Koc = m*log K´+ b

This equation is showing the corresponding relationship between Koc and retention time.

Type:

log Koc

Value:

ca. 1.25

Temp.:

26 °C

Details on results (HPLC method):

- Retention times of reference substances used for calibration: The used retention times are as follows:

Acetanilide: 3.621
Phenol: 3.783
Methyl benzoate: 5.054
Naphthalene: 7.469
Phenanthrene: 10.707
DDT: 31.066

- Details of fitted regression line (log k' vs. log Koc): y = 2.9649x + 2.4858, R2 = 0.964
- Graph of regression line attached: No
- Average retention data for test substance: The retention time of LiBOB was 3.838 min. resulting in a capacity factor K´ of 0.838 and a log Koc of 1.25.

Validity criteria fulfilled:

not specified

Conclusions:

Lithium bis(oxalato)borate was assessed in an adsorption study resulting in a log Koc of 1.25 (at 26 °C).

Executive summary:

Lithium bis(oxalato)borate (LiBOB) was assessed in an adsorption study, conducted with HPLC, according to OECD guideline 121. Acetanilide, Phenol, Methylbenzoate, Naphthalene, Phenanthrene and DDT were taken as reference substances. Sodium nitrate was used to determine the dead time of the column. The HPLC conditions were as follows:

apparatus: Agilent HPLC 1200

column: Agilent TC-C18 (4.6 mm, 250 mm, 5 µm)

mobile phase: water/acetonitrile (35%/65%)

injection volume: 10 µL

detector: VWD, 230 nm

The retention time of LiBOB was determined as 3.83 min resulting in a log Koc of 1.25 (at 26 °C). (Guizhou, 2010)

Description of key information

In accordance with column 2 of REACH Annex VIII, section 9.3.1, a study on adsorption and desorption does not need to be conducted, as the physico-chemical properties of the test substance indicate a low adsorption potential. LiBOB has a log Pow of -4.8. Nevertheless a study has been conducted with lithium bis(oxalato)borate, which resulted in a log Koc of 1.25 (at 26 °C), showing that the test substance does not likely absorb to particles and soil.
As the log Koc changes over time due to the degradation of LiBOB in water the log Koc of 1.25 from the study was not used for risk assessment.

Additional information

Lithium bis(oxalato)borate (LiBOB) was assessed in an adsorption study, conducted with HPLC, according to OECD guideline 121. Acetanilide, Phenol, Methylbenzoate, Naphthalene, Phenanthrene and DDT were taken as reference substances. Sodium nitrate was used to determine the dead time of the column. The retention time of LiBOB was determined as 3.83 min resulting in a log Koc of 1.25 (at 26 °C). (Guizhou, 2010)

The Koc value is the ratio of the concentration of the substance in soil/sludge and the concentration of the substance in the aqueous phase at adsorption equilibrium.

Koc= c(soil) / c(water)

Both sorption processes are linked with each other and are influenced by different parameters, e.g. physico-chemical properties of the substance. As the log Koc changes over time due to the degradation of LiBOB (please refer to IUCLID section 5.2) in water the log Koc of 1.25 from the study was not used for risk assessment.