Vanillin

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption, other

Remarks:

adsorption

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study not well documented but meets the general OECD Guideline 106 requirements.

GLP compliance:

not specified

Type of method:

batch equilibrium method

Media:

other: water - soil

Test temperature:

25 +/-0.5°C

Analytical monitoring:

yes

Details on sampling:

- Sampling interval: at 12 and 24hr of incubation

Details on matrix:

COLLECTION AND STORAGE
- Geographic location: soil sampled from east area in the country of the authors
- Collection procedures: no data
- Sampling depth (cm): no data
- Storage conditions: in the laboratory in a dry place at ambient temperature
- Storage length: no data
- Soil preparation (e.g.: 2 mm sieved; air dried etc.): air-dried, grounded to pas 60 mesh sievd


PROPERTIES: data only available:
- pH: 6.35
- Organic carbon (%): 1.85% determined by the walkley-Blank method

Details on test conditions:

Tested chemicals are prepared in 0.01M CaCl2 solution. One g soil is weighed into 10-ml glass centrifuged tubes, 10 ml solution are added,
and the tubes are sealed. After shaking for 12H, the tubes are centrifuged at 6000 rpm for 20 min.
Soil-free tubes containing only the initial solutions are used as blank references to check for sorption onto glass or caps.
There is no change in solution concentration between a 12- and 24-Hr equilibration.
The equilibrium concentrations for samples in the water phase are determined by UV/visible spectrophotometry.
The soil values are calculated by difference.
All measurement are carried out in duplicate.
There are 7-9 points in each isotherm.

Computational methods:

The sorption isotherms for all samples are analysed using the Freundlich model (eq 1). The Freundlich isotherm parameters (Kf and n) are
determined by the commonly applied method of a linear regression (eq 2) of the log-transformed data. This is justified because the relative error in measurement is not greatly dependant on concentration. Thus standard linear regression techniques are appropriate for the transformed data and
no weighting of the regression is required.
Eq 1: Cs = KfCeE+n,
Eq 2: LnCs = LnKf + nLnCe
where Cs is the solid-phase equilibrium concentration (µg/g) of solute, Ce is the solution-phase equilibrium concentration (µg/ml), Kf is a
freundlich affinity parameter for a hetero-disperse system, and n is related to the magnitude of the adsorption driving force and to the energy
distribution of the adsorption sites.

Adsorption and desorption constants:

LnKf has been determined to be 1.962 for vanillin, with n = 0.794, indicating a nonlinear isotherm where the marginal adsorption energy decreases
with increasing surface concentration.

Recovery of test material:

No data

Concentration of test substance at end of adsorption equilibration period:

No data

Concentration of test substance at end of desorption equilibration period:

Not applicable

Transformation products:

not specified

Statistics:

Regression analysis are performed using STATGRAPHICS program with a confidence limit of 95%

Conclusions:

LogKf has been determined to be 1.962 for vanillin in natural soil from China, with n = 0.794, indicating a nonlinear isotherm where the marginal
adsorption energy decreases with increasing surface concentration.
From this result, a LogKoc can be calculated:3.69 (Kf=Kd; Koc=Kd*100/1.85)

Executive summary:

Sorption of Vanillin on natural soil from China (pH=6.35; OC=1.85%) has been determined by batch equilibrium method (following OECD guideline). LogKf has been determined to be 1.962, with n = 0.794, indicating a nonlinear adsorption isotherm where the marginal adsorption energy decreases with increasing surface concentration. From this result, a LogKoc can be calculated:3.69 (Kf=Kd; Koc=Kd*100/1.85)

Reference 2

Endpoint:

adsorption / desorption, other

Remarks:

adsorption

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study not well documented but meets the general OECD Guideline 106 requirements

Guideline:

other: no data

GLP compliance:

not specified

Type of method:

batch equilibrium method

Media:

other: water - sediment

Test temperature:

25 +/- 0.5°C

Analytical monitoring:

yes

Details on sampling:

no data

Details on matrix:

DETAILS ON SEDIMENT: only these informations are available:
- Details on collection (e.g. location, depth, contamination history, procedure: Sediment taken from Yangtze River near
Nanjing City (N: 32deg13'13.5'', E: 118deg50'44.3'')
- Storage conditions: Stored in the laboratory in a dry place at ambient temperature
- Textural classification (i.e. %sand/silt/clay): no data
- pH at time of collection: 6.75
- Organic carbon (%): 1.57 determined by Walkley-Blank method
- Electrical conductivity:no data
- Redox potential (mv) initial/final:no data
- Bulk density (g/cm³):no data
- Biomass (e.g. in mg microbial C/100 mg, CFU or other):no data

- Sediment preparation: sediment air-dried and 0.177 mm sieved

Details on test conditions:

TEST SYSTEM
- Type, size and further details on reaction vessel: No details.
- Amount of sediment and water per treatment: No details
- Concentrations of the tested chemicals (including vanillin): 10-100 µg/ml
- Temperature: 25+/- 0.5°C
Sediment free tubes containing only the initial solutions were used as blank reference to check for sorption onto glass or caps
There were 7-9 points in each isotherm.
The equilibrium concentrations for samples in the water phase were determined by UV/visible spectrophotometry; the sediment values were
calculated by the difference.
All measurement was carried out in duplicate.
No other data available

Computational methods:

COMPUTATIONAL METHODS:
- Freundlich adsorption and desorption coefficients: 7.11
- Slope of Freundlich adsorption/desorption isotherms: No data
- Regression coefficient of Freundlich equation: No data
- Other: Each isotherm was modelled with 7-9 points.

The sorption isotherms were analysed using Freundlich equation Cs = KfCeE+N, where Cs was the amount of benzaldehyde sorbed (µmol/kg)
and Ce is the solution concentration (µmol/L). Kf and N are empirical constants, where Kf is the Freundlich coefficient (L/kg) and the exponent N is a dimensionless parameter commonly less that unity.
Non linear regression techniques used to derive Kf and N minimized the weighted residual sum of square.
Consequently, the sorption partition coefficient Kf is normalized for organic carbon to yield an organic-carbon-partition, Koc.

Type:

log Koc

Value:

3.438

Adsorption and desorption constants:

The value calculated using Freundlich isotherm is LogKoc=3.438

Recovery of test material:

No data

Concentration of test substance at end of adsorption equilibration period:

No data

Concentration of test substance at end of desorption equilibration period:

No data

Transformation products:

not specified

Conclusions:

Log Koc of vanillin has been determined by batch method based on the OECD guideline to be 3.438

Executive summary:

Log Koc of vanillin has been determined by batch method based on the OECD guideline to be 3.438

Reference 3

Endpoint:

adsorption / desorption, other

Type of information:

(Q)SAR

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Calculation from equation dicussed in the EU TGD.

Justification for type of information:

QSAR prediction

Principles of method if other than guideline:

QSAR calculation according to equation from Sabljic and Güsten (1995), as reported in the EU TGD (2003), concerning non hydrophobic chemicals:
logKoc = 0.52 logKow + 1.02, with LogKow=1.2

Type:

Koc

Value:

44

Type:

log Koc

Value:

1.64

Key value for chemical safety assessment

Koc at 20 °C:

4 898

Additional information

Two publications from Jin et al. (1997) and Dai et al. (2000), quoted in reliability 2 (since conducted following OECD 106) reported a log Koc of 3.69

(calculated from Kf) in natural soil from China (pH=6.35, OC=1.85%) and a log Koc=3.438 in natural sediment from China (pH=6.75, OC=1.57%).