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Endpoint:
adsorption / desorption: screening
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
2003
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification
Remarks:
A QSAR prediction was made using a validated model. A Klimisch 3 score was assigned because the QSAR specifically reports that Koc values are usually underestimated (1-2 log-units) for aliphatic amines.
Qualifier:
according to guideline
Guideline:
other: TGD Part III on QSARs, 2003
Principles of method if other than guideline:
Model for nonhydrophobics (Sabljic and Güsten, 1995).
Type of method:
other: QSAR estimate
Media:
soil
Specific details on test material used for the study:
Log Kow value of 2.0 was used for calculation.
Computational methods:
A QSAR for nonhydrophobics was used for log Koc estimation based on the log Kow. The model was first reported by Sabljic and Güsten (1995) and mentioned in the TGD (2003). See below for further details.
Type:
log Koc
Value:
2.06
Remarks on result:
other: QSAR estimate

A QSAR for nonhydrophobics was used for log Koc estimation based on the log Kow. The model was first reported by Sabljic and Güsten (1995) and mentioned in the TGD (2003). Validity of model:

1. Defined endpoint: adsorption/desorption (log Koc).

2. Unambiguous algorithm: linear regression QSAR; log Koc = 0.52 x log Kow + 1.02.

3. Applicability domain: all chemicals not classified as hydrophobics, with a log Kow below 8.0 (and above -2.0).

4. Statistical characteristics: n = 390; R2 = 0.63; SE = 0.56.

5. Mechanistic interpretation: related to the partitioning of the substance from water into the organism's lipid phase.

Adequacy of prediction:

The substance falls within the applicability domain described above and therefore the predicted value can be considered reliable. However, next to a standard error of 0.56, it is mentioned that for aliphatic amines the model generally underestimates the log Koc by 1 -2 log units. Therefore, as long as no testing data or more accurate QSAR predictions are available, the estimate should be used with caution.

Validity criteria fulfilled:
not applicable
Conclusions:
The QSAR for nonhydrophobics of Sabljic and Güsten (1995), reported by the TGD (2003) of the European Commission, was used for calculation of a log Koc based on the log Kow. Using this model, a log Koc of 2.06 was calculated. Because for aliphatic amines the model is known to underestimate the log Koc (by 1-2 log units), the predicted value should be used with caution.
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 December 2011 - 10 January 2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Study performed according to guideline similar to OECD guideline 106. The pH was not monitored in the aqueous phase, which is strongly advised when testing adsorption of ionisable test substances.
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)
Deviations:
yes
Remarks:
pH not monitored in aqueous phase
Qualifier:
according to guideline
Guideline:
other: Guidelines for the testing of chemicals (HJ/T 153-2004, SEPA)
GLP compliance:
yes
Type of method:
batch equilibrium method
Media:
soil
Specific details on test material used for the study:
- Name of test material (as cited in study report): XTJ-568
- Substance type: colourless
- Physical state: liquid
- Analytical purity: 97.8%
- Lot/batch No.: not reported
- Stability under test conditions: not reported
- Storage condition of test material: at room temperature in the dark
- Expiration date: 20 May 2013
- Other:
* pH: 12.4
* solubility in water: soluble
Test temperature:
23 ± 1 °C
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 5 mg/L
- Sampling interval: 0, 6, 10, 24, and 48 hours
- Sample storage before analysis: in refrigerator at 4 °C
- An aliquot of the supernatant was collected after centrifuging the soil mixtures.
Details on matrix:
COLLECTION AND STORAGE
- Geographic location: China
- Collection procedures: soils were provided by Nanjing Institute of Soil Science Chinese Academy of Sciences
- Storage conditions: at ambient temperature and air-dried
- Storage length: not reported
- Soil preparation (e.g.: 2 mm sieved; air dried etc.): soils were sieved to particle size < 2 mm

PROPERTIES
- Moisture content was determined on three aliquots with heating to 105 °C, until no significant change in weight was observed (approximately 12 h)

- Jiangxi red soil: #1
- clay
- pH: 5.29
- Organic carbon (%): 0.99 %
- CEC (cmol/kg): 10.6 cmol/kg
- Clay fraction mineralogy: 5 %
- Dry mass (%, 105 °C, 12h): 95.14 %

- Nanjing yellow brown soil: #2
- clay loam
- pH: 6.23
- Organic carbon (%): 1.21 %
- CEC (cmol/kg): 17.4 cmol/kg
- Clay fraction mineralogy: 18 %
- Dry mass (%, 105 °C, 12h): 93.42 %

- Shanxi grey desert soil: #3
- silt loam
- pH: 7.80
- Organic carbon (%): 2.60 %
- CEC (cmol/kg): 27.5 cmol/kg
- Clay fraction mineralogy: 16 %
- Dry mass (%, 105 °C, 12h): 99.25 %


Details on test conditions:
TEST CONDITIONS
- pH: not measured in aqueous solutions (strongly advised for ionisable substances, in view of the evaluation of pH dependency of adsorption)
- Temperature: room temperature was 23 ± 1°C (raw data not reported)
- Test performed in closed vessels due to significant volatility of test substance: vessels were capped to prevent volatility as well as water loss.

TEST SYSTEM
- Type, size and further details on reaction vessel: 40-mL glass tube with cap
- Aqueous solvent phase: 0.01 M CaCl2 solution in distilled water
- Soil-solution ratio: 1:5
- Test substance dissolved at 5.0 mg/L in aqueous phase.
- Blanks: background control without test substance, stability control without soil to check stability in CaCl2 solution and possible adsorption to test vessel.
- Soil and solution were agitated for 48 h at 40 rpm.
- At 0, 6, 10, 24 and 48 h, soil mixtures were centrifuged at 3000 rpm for 10 min.
- Supernatant samples collected and stored in refrigerator until analysis.
- Number of reaction vessels/concentration: 3 replicates (only 1 for each blank)
- Desorption was not studied (adsorption < 25 %)

REFERENCE SUBSTANCE
- Naphthalene was used as reference substance.
- The Koc of napthalene was determined periodically.
- The Koc should be 739-7671 in Jiangxi red soil, 772-20088 in Nanjing yellow brown soil, and 1441-32577 in Shanxi grey desert soil (which was the case).
Computational methods:
- Adsorption coefficient:
Kd = C(s)/C(aq) = m(s) . V0/m(aq) . m(soil), with:
* C(s): content of the substance adsorbed on the soil at adsorption equilibrium (µg/g)
* C(aq): mass concentration of the substance in the aqueous phase at adsorption equilibrium (µg/cm³). This concentration is analytically determined taking into account the values given by the blanks.
* m(s): mass of the substance adsorbed on the soil at adsorption equilibrium
* m(aq): mass of the substance in the solution at adsorption equilibrium (µg)
* m(soil): quantity of the soil phase, expressed in dry mass of soil (g)
* V0: initial volume of the aqueous phase in contact with soil (cm³)

- Adsorption coefficient per organic carbon (Koc):
Koc = Kd . 100/% oc (cm³/g), with:
* % oc: percentage of organic carbon in the soil sample (g/g)


Type:
Koc
Remarks:
24 h
Value:
60.3
% Org. carbon:
0.99
Remarks on result:
other: #1 Jiangxi red soil
Type:
Koc
Remarks:
24 h
Value:
61.4
% Org. carbon:
1.21
Remarks on result:
other: #2 Nanjing yellow brown soil
Type:
Koc
Remarks:
24 h
Value:
33.2
% Org. carbon:
2.6
Remarks on result:
other: #3 Shanxi grey desert soil
Recovery of test material:
- Recovery of the test substance control: 97.3 % after 48 hour agitation (no soil)
Concentration of test substance at end of adsorption equilibration period:
- adsorption period: 48 h
- #1: JJiangxi red soil: 4.455 mg/L
- #2: Nanjing yellow brown soil: 4.33 mg/L
- #3: Shanxi grey desert soil: 4.255 mg/L
Concentration of test substance at end of desorption equilibration period:
Since the adsorption percentage of the test substance for all three soils was less than 25%, desorption was not studied.
Transformation products:
not specified
Details on results (Batch equilibrium method):
- Adsorption equilibration time was 10, 10, and 24 h in soil #1, #2, and #3, respectively.
- 10.7, 12.9, and 14.7% of the initially added amount of test substance was adsorbed after 48 h in soil #1, #2, and #3, respectively.
Validity criteria fulfilled:
yes
Conclusions:
The study investigated the adsorption of the substance to three soils differing in pH (ranging from 5.29 to 7.80), organic carbon content (ranging from 0.99% to 2.60%), cation exchange capacity (ranging from 10.6 to 27.5 cmol/kg) and clay content (ranging from 5% to 16%). For each soil, the adsorption efficiency (%), adsorption coefficient (Kd), Koc, and log Koc were determined at 24 hours. Adsorption efficiency ranged from 10.7% to 14.7%, leading to Koc values between 33.2 and 61.4 (log Koc values between 1.52 and 1.79). The pH in the aqueous phase was not monitored, hence the pH dependency of adsorption is not clear from this study.
Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
14 February 2011 and 22 February 2011
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification
Remarks:
Adsorption coefficients were estimated using a QSAR prediction according to a validated model. A Klimisch 3 score was assigned because an estimated log Kow was used while a measured value is available, and because the guidance document states that the Koc values may be systematically underestimated by the method by 1 to 2 log units. The final results represent the corrected log Koc values.
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:
method seemed invalid for the test item
Qualifier:
according to guideline
Guideline:
other: technical guidance documents in support of Commission Directive 93/67/EEC on risk assessment for new substances
Principles of method if other than guideline:
As the testing method (HPLC method) was found to be invalid for the test item, estimated values for the adsorption coefficient were obtained by calculation using Quantitative Structure Activity Relationships (QSAR's). The dissociation constants of the primary amine functional groups found in the test item components (see Attached documents) were predicted to be approximately 9.2 (using specialised computer estimation software, SPARC v4.5). Therefore, the test item would maintain at least a single cationic charge over the entire environmentally relevant pH range of 5.5 to 7.5 applicable for the method. Cationic species have been demonstrated to interact with the HPLC column stationary phase by mechanisms other than partitioning, thus invalidating the estimation of the adsorption coefficient of the test item by comparison to the capacity factors of reference substances of known adsorption coefficient values.
GLP compliance:
yes
Type of method:
other: QSAR calculation
Media:
other: no final test performed
Specific details on test material used for the study:
- Name of test material (as cited in study report): XTJ 568
- Physical state: extremely pale yellow liquid
- Analytical purity: 97.2 % (primary amine)
- Lot/batch No.: DR32630507
- Expiration date of the lot/batch: 31 December 2011
- Storage condition of test material: room temperature in the dark
- see Attached documents for chemical structure of test item: component 1 and component 2
Radiolabelling:
no
Test temperature:
Not applicable.
Details on study design: HPLC method:
Preliminary testing was performed both with and without a cyanopropyl HPLC column, using evaporative light scattering detection and ultraviolet detectors.
Analytical monitoring:
no
Computational methods:
- Dissociation constants of the primary amine functional groups were predicted to be approximately 9.2 using specialised computer estimation software SPARC v4.5.
- Estimated values for the partition coefficients of the test item components were sourced from EPISuite version 4.00, KOWWIN v1.67a (Sept 2008), U.S. Environmental Protection Agency.
- QSAR calculation for nonhydrophobics: log10 Koc = 0.52 x log10 Pow + 1.02, with Koc = adsorption coefficient and Pow = partition coefficient.
Type:
log Koc
Value:
2.8 - 3.2
Remarks on result:
other: Values for component 1 and 2, corrected for underestimation.
Details on results (HPLC method):
Preliminary test:
With no column in place the test item could be easily detected, however, with the cyanopropyl HPLC column in place, no test item could be reliably detected even when a 100 % solvent ramp was used. Retention of the test item was attributed to strong secondary ionic interaction with the column phase as opposed to true partitioning, thus invalidating the HPLC estimation method. Therefore, due to the unsuitability of the HPLC method, an estimation of the adsorption coefficient of the test item was performed.

The estimated partition coefficients (log10 Pow) and resultant calculated adsorption coefficients (log10 Koc) of the test item components are:

component 1: log10 Pow = -0.35 and log10 Koc = 0.84 (before correction)

component 2: log10 Pow = 0.28 and log10 Koc = 1.17 (before correction)

As the adsorption coefficient of alkyl amines maybe systematically underestimated by the method by 1 or 2 log units, the maximum possible correction factor was applied to the results to represent a worst case scenario. This resulted in estimated values of log10 Koc = 2.8 and 3.2 for components 1 and 2, respectively.

Validity criteria fulfilled:
not applicable
Conclusions:
Estimated and corrected adsorption coefficients (log Koc) of the test item components were found to be 2.8 and 3.2 for component 1 and component 2, respectively, using QSAR calculations.

Description of key information

Based on the results of a batch equilibrium experiment in which the adsorption of the substance to three different soils with varying properties was investigated, a key Koc value of 49.7 (geometric mean of three Koc values) was selected as key value for the CSA. This corresponds to a log Koc value of 1.7. Because pH was not monitored in the aqueous solution, the pH dependency of adsorption of this ionisable substance could not be evaluated. Therefore the study was scored as Klimisch 2.

Key value for chemical safety assessment

Koc at 20 °C:
49.7

Additional information

Based on a calculation of the pKa's and the results of the determination of the log Kow, it is clear that the test substance is ionized for at least 10% in the range pH 5.5 -7.5. Therefore both the ionized and the unionized form should be tested in appropriate buffer solutions. Since the highest pKa was calculated to be 9.9, the test substance must be tested both at a pH of > 10.9 (neutral form) and at a pH < 8.9 (ionized form). Due to the limited pH range of the cyanopropyl column required for the OECD 121 method, testing at pH > 10.9 is impossible. Testing at pH < 8.9 is in principle possible, but due to the very unfavorable interaction of the protonated form of the test substance with residual silanol groups of the stationary phase, test substance peak shape and retention time reproducibility will be extremely poor. Therefore, it is not possible to determine the partition constant according to the OECD 121 method (HPLC method).

Alternatively, a batch equilibrium test was performed (Environmental Testing Laboratory, 2012) according to a guideline similar to OECD guideline 106. In this study, the adsorption of the substance was studied in three different Chinese soils with variable properties (pH, organic carbon, CEC, % clay). The log Koc values obtained in these soils range from 1.52 to 1.79. Although for this substance it would have been interesting to investigate pH dependency of adsorption, no information on this is obtained since pH was not monitored in the aqueous phase. Therefore, this study was scored as Klimisch 2.

As supporting information, several QSAR estimates can be used. The QSAR for nonhydrophobics reported by Sabljic and Güsten (1995) and reported in the TGD (2003) of the European Commission yields a log Koc of 2.06 (using a linear regression equation based on the log Kow). This value may be underestimated since the model may underestimate the log Koc of aliphatic amines by 1-2 log units. Therefore, the value should be used with caution. NOTOX Project 375637 presents another QSAR prediction (also based on log Kow), in which the final values were (worst case) corrected for the possible underestimation for aliphatic amines. The resulting values were log Koc = 2.8 and 3.2 for two components, respectively. Here too, these values should be used with caution. Therefore, both QSAR estimates represent supporting information.