[No public or meaningful name is available]

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Data waiving:

study technically not feasible

Justification for data waiving:

other:

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))

GLP compliance:

no

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Validity criteria fulfilled:

not applicable

Conclusions:

The determination of the adsorption coefficient (KOC) of Licocare RBW 300 on soil and on sewage sludge using HPLC acc. to OECD 121 (2001) and Council Regulation (EC) No. 440/2008, C.19 is not feasible, because the test item is not sufficiently soluble in solvents suitable for HPLC analysis.

Executive summary:

Preliminary investigations (non-GLP) for the determination of the adsorption coefficient K_OC of Licocare RBW 300 on soil and on sewage sludge using high performance liquid chromatography (HPLC) were performed according to OECD 121 and Council Regulation (EC) No.440/2008, Method C.19 at Noack Laboratorien GmbH, 31157 Sarstedt, Germany.

 

The results of these experiments showed that this guideline is not applicable for the determination of the adsorption coefficient (K_OC) of Licocare RBW 300 on soil and on sewage sludge because the test item is not sufficiently soluble in solvents suitable for HPLC‑analysis.

 

 

This guideline is not applicable for the determination of the adsorption coefficient (K_OC) of the test item on soil and on sewage sludge, because the test item is not sufficiently soluble in suitable solvents.

 

Reference 2

Endpoint:

adsorption / desorption, other

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

supporting study

Study period:

2022

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Type:

log Koc

Value:

1.21

Conclusions:

Based on this formular Log Koc was calculated as

Log Koc = 0.8679 x 1.4 – 0.0004

Log Koc = 1.21

Executive summary:

The software program KOCWIN^TM is part of the Estimations Programs Interface for Windows (EPI Suite^TM). It is a Windows^®-based suite of physical/chemical property and environmental fate estimation programs developed by the US Environmental Protection Agency (EPA) and Syracuse Research Corp. (SRC). The estimation methods in EPI Suite™ have been developed by government, academic, and private sector researchers over many years and represent some of the best techniques currently available.

The intended application domain of EPI Suite is organic chemicals, and inorganic as well as organometallic chemicals generally can be considered outside the domain. Data files are available containing the experimental data sets used to derive and validate program methodologies or test program accuracy.

KOCWIN™ estimates the organic carbon-normalized sorption coefficient for soil and sediment; i.e. KOC. KOC is estimated using two different models: the Sabljic molecular connectivity method with improved correction factors; and the traditional method based on log KOW.

The US EPA is using this predictive model for assessing chemicals under the Toxic Substance Control Act (TSCA). The tool is also accepted by ECHA and explicitly mentioned in the “Guidance on information requirements and chemical safety assessment, Chapter R.6: QSARs and grouping of chemicals”.

A traditional method of estimating soil adsorption Koc involves correlations developed with log octanol-water partition coefficient (log Kow). Since an expanded experimental Koc database was available from the new MCI regression, it was decided to develop a log Kow estimation methodology that was potentially more accurate than existing log Kow QSARs for diverse structure datasets.

Effectively, the new log Kow methodology simply replaces the MCI descriptor with log Kow and derives similar equations.  The derivation uses the same training and validation data sets.  The training set is divided into the same non-polar (no correction factors) and correction factor sets.  

The same correction factors are also used. Separate equations correlating log Koc with log Kow were derived for nonpolar and polar compounds because it was statistically more accurate to do so than to use the approach taken with the MCI-based method.  The equation derived by the non-polar (no correction factor) regression is:

log Koc  =  0.8679 Log Kow  -  0.0004

 

 

Based on this formular Log Koc was calculated as

Log Koc = 0.8679 x 1.4 – 0.0004

Log Koc = 1.21

 

Reference 3

Endpoint:

adsorption / desorption: screening

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Qualifier:

according to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

GLP compliance:

yes

Type of method:

batch equilibrium method

Media:

soil

Validity criteria fulfilled:

not applicable

Conclusions:

In combination, these facts impairs the accurate dedcution of the study endpoints required by the guideline OECD106 because a reliable and sensitive quantitation of the test item in the aqueous phase during the experiments is mandatory for their calculation. But this is questionale due to the low water solubility, the low sensitivity of the analytical method and taking into account a decline of the test item concentration in the aqueous phase during the experiments by adsorption.

Executive summary:

 

Analytical monitoring of the test tem in the aqueous phase of soil suspensions used in an adsorption / desorption study according to the guideline OECD 106 is not possible due to the low water solubility of the test item and high analytical detection limit / low sensitivity of the analytical method. Notest item could be detected in aqueous samplesof aquatoxicity studies (Noack ID180706CM/ DAI18315andSPO18315) when test sampleswere prepared as water accommodated fractions (WAF).Only approximately 0.1 to 1 mg test item/L can be detected though a LC-MS/MS, known as analytical device enabling the implementation of analytical methods with highest sensitivity, was used. Furthermore, no stock solutions of the test item for application in concentrations adequate for analytical monoitoring during the adsorption experiments can be prepared because only 50 mg test item/L can be dissolved in toluene under heating.

In combination, these facts impairs the accurate dedcution of the study endpoints required by the guideline OECD106 because a reliable and sensitive quantitation of the test item in the aqueous phase during the experiments is mandatory for their calculation. But this is questionale due to the low water solubility, the low sensitivity of the analytical method and taking into account a decline of the test item concentration in the aqueous phase during the experiments by adsorption.

 

1      Literature

▪       OECD 106Guideline for the Testing of Chemicals ‑ Adsorption / Desorption using a Batch Equilibrium Method (2000)

▪       Council Regulation (EC) No. 440/2008, Method C.18 -Adsorption / Desorption using a Batch Equilibrium Method

▪       Acute Immobilization Test toDaphnia magna, Semi-static, 48 hours,acc. toOECD-Guideline 202 for Testing of Chemicals (2004),(Noack ID180706CM/ DAI18315), Noack Laboratorien GmbH, 2019

▪       Alga, Growth Inhibition Test withPseudokirchneriella subcapitata,72 hours, acc. to  OECD 201 (2011)andCouncil Regulation (EC) No. 266/2016 Method C.3,(Noack ID180706CM/ SPO18315), Noack Laboratorien GmbH, 2019

 

Description of key information

Preliminary investigations (non-GLP) for the determination of the adsorption coefficient K_OC of Licocare RBW 300 on soil and on sewage sludge using high performance liquid chromatography (HPLC) were performed according to OECD 121 and Council Regulation (EC) No.440/2008, Method C.19 at Noack Laboratorien GmbH, 31157 Sarstedt, Germany.

The results of these experiments showed that this guideline is not applicable for the determination of the adsorption coefficient (K_OC) of Licocare RBW 300 on soil and on sewage sludge because the test item is not sufficiently soluble in solvents suitable for HPLC‑analysis.

 

The determination of the studies according OECD 121 was not possible because the test item is not sufficiently soluble in solvents suitable for HPLC‑analysis and due to the low water solubility of the test item and high analytical detection limit / low sensitivity of the analytical method (OECD 106)

OECD 106

Analytical monitoring of the test tem in the aqueous phase of soil suspensions used in an adsorption / desorption study according to the guideline OECD 106 is not possible due to the low water solubility of the test item and high analytical detection limit / low sensitivity of the analytical method. Notest item could be detected in aqueous samplesof aquatoxicity studies (Noack ID180706CM/ DAI18315andSPO18315) when test sampleswere prepared as water accommodated fractions (WAF).Only approximately 0.1 to 1 mg test item/L can be detected though a LC-MS/MS, known as analytical device enabling the implementation of analytical methods with highest sensitivity, was used. Furthermore, no stock solutions of the test item for application in concentrations adequate for analytical monoitoring during the adsorption experiments can be prepared because only 50 mg test item/L can be dissolved in toluene under heating.

In combination, these facts impairs the accurate dedcution of the study endpoints required by the guideline OECD106 because a reliable and sensitive quantitation of the test item in the aqueous phase during the experiments is mandatory for their calculation. But this is questionale due to the low water solubility, the low sensitivity of the analytical method and taking into account a decline of the test item concentration in the aqueous phase during the experiments by adsorption.

 

OECD 121

 

The determination of the adsorption coefficient (KOC) of Licocare RBW 300 on soil and on sewage sludge using HPLC acc. to OECD 121 (2001) and Council Regulation (EC) No. 440/2008, C.19 is not feasible, because the test item is not sufficiently soluble in solvents suitable for HPLC analysis.

 

Estimation

 

The software program KOCWIN^TM is part of the Estimations Programs Interface for Windows (EPI Suite^TM). It is a Windows^®-based suite of physical/chemical property and environmental fate estimation programs developed by the US Environmental Protection Agency (EPA) and Syracuse Research Corp. (SRC). The estimation methods in EPI Suite™ have been developed by government, academic, and private sector researchers over many years and represent some of the best techniques currently available.

The intended application domain of EPI Suite is organic chemicals, and inorganic as well as organometallic chemicals generally can be considered outside the domain. Data files are available containing the experimental data sets used to derive and validate program methodologies or test program accuracy.

KOCWIN™ estimates the organic carbon-normalized sorption coefficient for soil and sediment; i.e. KOC. KOC is estimated using two different models: the Sabljic molecular connectivity method with improved correction factors; and the traditional method based on log KOW.

The US EPA is using this predictive model for assessing chemicals under the Toxic Substance Control Act (TSCA). The tool is also accepted by ECHA and explicitly mentioned in the “Guidance on information requirements and chemical safety assessment, Chapter R.6: QSARs and grouping of chemicals”.

A traditional method of estimating soil adsorption Koc involves correlations developed with log octanol-water partition coefficient (log Kow). Since an expanded experimental Koc database was available from the new MCI regression, it was decided to develop a log Kow estimation methodology that was potentially more accurate than existing log Kow QSARs for diverse structure datasets.

Effectively, the new log Kow methodology simply replaces the MCI descriptor with log Kow and derives similar equations.  The derivation uses the same training and validation data sets.  The training set is divided into the same non-polar (no correction factors) and correction factor sets.  

The same correction factors are also used. Separate equations correlating log Koc with log Kow were derived for nonpolar and polar compounds because it was statistically more accurate to do so than to use the approach taken with the MCI-based method.  The equation derived by the non-polar (no correction factor) regression is:

log Koc  =  0.8679 Log Kow  -  0.0004

 

 

Based on this formular Log Koc was calculated as

Log Koc = 0.8679 x 1.4 – 0.0004

Log Koc = 1.21

 

Key value for chemical safety assessment

Koc at 20 °C:

16.22