Reaction product of ammonium molybdate and C12-C24-diethoxylated alkylamine (1:5-1:3)

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

other: feasibility assessment

Study period:

2011

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Qualifier:

no guideline followed

Guideline:

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

Version / remarks:

. Feasibility assessment also considered the HPLC estimation method as detailed in Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

Deviations:

not applicable

Remarks:

The overall conclusion was that the limited water solubility, high expected affinity for soils and complex composition prevented use of the batch equilibrium methods. The presence of surface active properties also invalidated the use of HPLC method.

GLP compliance:

no

Remarks:

Principles of GLP are not applicable to non-experimental assessments of physico-chemical properties.

Test material

Test material information

Constituent 1

Reference substance name:

Additive 104

IUPAC Name:

Additive 104

Constituent 2

Reference substance name:

Reaction product of ammonium molybdate and C12-C24-diethoxylated alkylamine (1:5-1:3)

EC Number:

412-780-3

EC Name:

Reaction product of ammonium molybdate and C12-C24-diethoxylated alkylamine (1:5-1:3)

Cas Number:

1380226-46-9

Molecular formula:

A complex mixture of species so no unique molecular formula can be given

IUPAC Name:

dimolybdenum(6+) diammonium 2-{2-[(octadec-9-en-1-yl)amino]ethoxy}ethan-1-ol heptaoxidandiide

Details on test material:

Sponsor's identification : Additiv 104
Chemical name : Reaction product of ammonium molybdate and C12-C24-diethoxylated alkylamine (1:5-1:3)
Purity : 100%
Chemical class : UVCB
CAS No. : Not available
EC No. : 412-780-3
Appearance : Viscous liquid without deposit, dark red

Additional structural/compositional information used for the assessment of experimental testing feasability is presented in the relevent attachment.

Radiolabelling:

no

Study design

Batch equilibrium or other method

Computational methods:

Estimation of the water solubility, partition coefficient and adsorption coefficient of individual proposed test item components were performed using the appropriate EPIWIN models (WSKOWWIN, KOWWIN and KOCWIN respectively) during assessment of experimental feasability.

Results and discussion

Any other information on results incl. tables

Feasibility Assessment

With respect to the possibility of performing an adsorption coefficient study by the batch equilibrium method, a significant amount of evidence was available to confirm the unsuitability of this procedure to the test item. This included:

• The test item is essentially insoluble in water; however OECD Method 106 requires that the nominal working concentration for the study remains below the water solubility of the test item; typically half saturation concentration is applied as the maximum concentration. This would require an initial fortification concentration of 0.2 µg/l or lower (≤2 x 10^-7g/l), even based on the most soluble component of the test item. OECD Method 106 also requires the availability of an analytical method with a limit of detection at least two magnitudes below that of the nominal working concentration, thus this criterion can not be satisfied using available chromatographic techniques. 
• As an alternative to the above, the possibility of performing the determination using radiochemical detection for the test item was assessed. From compositional data supplied by the Sponsor, based on¹⁴C labelling, it was predicted that the maximum theoretical specific activity, if synthesis could be successfully completed, would be approximately 4500 Bq/µg. To predict the activity remaining in the aqueous phase, estimations of adsorption coefficient (K_oc) were generated, again using the EPIWIN software suite. This resulted in log₁₀K_ocvalues of 6.6, 11.1 and 17. Even on using the lowest estimated adsorption coefficient value, based on 5% organic carbon content for the soil, and employing a 1:100 soil to solution ratio (the maximum recommended by the OECD guideline), the resulting distribution coefficient (K_d) value indicated that 99.950% adsorption onto the soil phase was anticipated. Thus to further complicate matters, not only would the initial dosed activity be limited, but due to the magnitude of adsorption expected, the remaining activity remaining in the aqueous phase for analysis would be negligible. Based on the lowest estimation of adsorption coefficient obtained this activity would be less than 0.1 dpm and for the higher values this would decrease further by several magnitudes; whereas the limit of quantification for the detector is 10 dpm.

A number of other potential difficulties were highlighted during this assessment including:

• The test item is an extremely complex substance. The batch equilibrium method guidelines recommend a minimum purity value of 95% for the procedure, as it is designed to study only a single compound. As the analytical method is not substance/species specific, only a single average distribution coefficient and adsorption coefficient value for the test item as a whole would be determined, whereas it is known to contain a number of distinct components, predicted to have individual adsorption coefficient values covering a range of a number of log units.
• Due to the high percentage adsorption predicted, the analysis would be extremely prone to interference from any “hot” impurities present in the radiolabelled test item.
• The predicted percentage adsorption indicates that the adsorption coefficient of the test item exceeds the range intended for quantification by the OECD 106 procedure. One of the analytical method validation requirements is that the limit of detection must be at least two magnitudes below the working concentration. This is in order to allow quantification of percentage adsorptions up to 99%. In this case the predicted percentage adsorption was ≥99.950% and therefore the limit of detection would need to be at least four magnitudes below the working concentration.
• OECD Method 106 states that the procedure may not be suitable for items with a partition coefficient value greater than 1 x 10⁴, i.e. log₁₀P_ow= 4.0, and in such cases estimation techniques may be more applicable. This is since suitable methodology is not available to generate homogeneous soil to solution mixtures at a suitable ratio which would retain sufficient test item in the aqueous phase to allow analytical quantification as demonstrated above. The partition coefficient of the test item has been estimated by Harlan Laboratories to be log₁₀ P_ow ≥8.50, using the EPIWIN software suite and compositional information supplied by the Sponsor.

The confirmation of surface active properties for the test item also invalidates the alternative HPLC estimation method, which is better suited to the determination of adsorption coefficient for complex mixtures and substances with a higher affinity for organic matter.

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Conclusions:

Based on the results of the assessment made, it was concluded that experimental determination of valid adsorption coefficient data would not be feasible. The limited water solubility, high expected affinity for soils and complex composition prevents use of batch equilibrium methods. The presence of surface active properties also invalidates the use of HPLC estimation methods.

Estimations of adsorption coefficient (Koc) were generated, using the EPIWIN software suite. This resulted in log10Koc values of 6.6, 11.1 and 17.

Executive summary:

A feasibility assessment for generation of experimental adsorption coefficient data on the test item was performed assessing both batch equilibrium methods (Method 106 of the OECD Guidelines for Testing of Chemicals, 21 January 2000 and Method C18 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008) and HPLC estimation methods (Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001 and Method C19 Adsorption Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008).

The overall conclusion was that the limited water solubility, high expected affinity for soils and complex composition prevents use of the batch equilibrium methods. The presence of surface active properties also invalidates the use of HPLC estimation methods.

Estimations of adsorption coefficient (K_oc) were generated, using the EPIWIN software suite. This resulted in log₁₀ K_ocvalues of 6.6, 11.1 and 17.