Pentapotassium bis(peroxymonosulphate) bis(sulphate)

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2001-03-22 to 2001-03-26

Reliability:

1 (reliable without restriction)

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

Principles of method if other than guideline:

NA

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Radiolabelling:

no

Test temperature:

NA

Details on study design: HPLC method:

Principle of the method
Chemicals injected onto a cyano column move along it by partitioning between the mobile phase and the stationary phase. The velocity of each component thereby depends on the degree of adsorption in the stationary phase. The dual nature of the moderately polar stationary phase, which contains lipophilic and polar moieties, allows for interaction of polar and apolar parts of a molecule in a similar way as in the case for soil. This enables the relationship between retention time on such a column and the adsorption coefficient on the organic parts of the soil to be established. The adsorption coefficient is deduced from the capacity factor (k) using a calibration plot of log k versus log Koc of the selected reference compounds. The capacity factor is calculated from the equation:
k = (tr-to)/to
where
to = column dead time (retention time of an inert substance)
tr = retention time of the test substance/reference compound

Measurement of dead time
The dead time (the average time a solvent molecule needs to pass through the column) was taken as the elution time of the thiourea, an organic compound for this purpose.

Preparation of the reference solutions
In order to correlate the measured capacity factor (k) of the test material with its Koc, six reference compounds are normally selected from the list of recommended compounds. However, in this particular case, preliminary results indicated that KMPS triple salt was not retained on the column. Therefore only two were selected in order to demonstrate that these were indeed retained.
Stock solutions of thiourea and of the reference compounds were prepared in methanol/water, 55/45 v/v. Individual solutions of thiourea and of each reference compound were then prepared by diluting the stock solutions with methanol/water, 55/45 v/v. The reference compound (and concentration) used were thiourea (5.54 mg/L), acetanilide (9.82 mg/L) and atrazine (3.17 mg/L). These solutions were analysed by HPLC to determine the individual retention times.

Preparation of test solution
KMPS triple salt (0.25048 g) was weighed into a 100 ml volumetric flask, and dissolved in and diluted to volume with water. An aliquot (9ml) was then pipetted into a 20 ml volumetric flask, and diluted to volume with methanol, in duplicate, to give solutions of concentration 1127.2 mg/L in methanol/water, 55/45 v/v. Injections (50 µl) were made onto the HPLC column from these solutions.
Methanol/water 55/45, v/v, was injected onto HPLC column, under the same conditions as the test solution, to act as blank solution.

HPLC conditions
HPLC system:
Autosampler: Moedl ISS200, Perkin Elmer
Detector: Model 481, Water Associates
Pump: Model 510, Water Associates
Data handling system: Turbochrom, PE Nelson
Column: Cyano Apex, 5 µm, 25 cm * 4.6 mm id.
Mobile phase: Methanol/water, 55/45, v/v
Flow rate: 1 ml/min
Comunm temperature: 20 °C
Injection volume: 50 µl
Detection: 210 nm

Analytical monitoring:

not specified

Details on sampling:

not indicated

Details on matrix:

not indicated

Details on test conditions:

not indicated

Computational methods:

not indicated

Key result

Type:

Koc

Value:

< 18

Key result

Type:

log Koc

Value:

< 1.25

Details on results (HPLC method):

The dead time (to), as determined from the retention time of thiourea, was 3.26 minutes. The retention time of acetanilide was 3.79 minutes (0.49 µg injected) and that of atrazine was 4.17 minutes (0.16 µg injected).
KMPS triple salt chromatographed as a single peak with retention times from the two injections of 2.15 and 2.16 minutes (the mass of the test substance introduced onto the column in each injection was 56 µg). Hence, log Koc will be quoted as being less than that of the fastest-eluting reference compound (acetanilide, which has a log Koc of 1.25 and a Koc of 18).
It was evident that thiourea was not a suitable compound for the assessment of the dead time of the column, as it eluted after the test substance. However, as the result from the test is being quoted as a limit value, it does not affect the validity of the conclusion drawn.
No peaks were seen in the blank solution chromatogram at the expected retention time of KMPS triple salt or at the characteristic retention times of two reference compounds.
There was no evidence of the column degradation in this study: reference compounds injected before and after the test substance produced peaks with no difference in retention time or peak shape.

Adsorption and desorption constants:

not indicated

Recovery of test material:

not indicated

Concentration of test substance at end of adsorption equilibration period:

not indicated

Concentration of test substance at end of desorption equilibration period:

not indicated

Transformation products:

not specified

Details on results (Batch equilibrium method):

not indicated

Statistics:

NA

no remarks

Validity criteria fulfilled:

not specified

Conclusions:

The soil adsorption coefficient of Oxone® Monopersulfate Compound has been determined as:
Koc < 18 at 20 °C
The result indicates that the test substance is likely to have very high mobility in soils.

Executive summary:

The study was performed to determine the soil adsorption coefficient (Koc) of Oxone® Monopersulfate Compound. The method followed was amongst those described in the OECD Guidelines for the testing of Chemicals. The result from the study is summarised below:

OECD-Method	Test	Result
Draft Guideline 121	Soil adsorption coefficient	Koc < 18 at 20 °C

The result indicates that the mobility of the test substance in soils is very high.

The result also indicates that the test substance is not likely to adsorp to sewage sludge in significant amounts.

Reference 2

Endpoint:

adsorption / desorption: screening

Data waiving:

other justification

Justification for data waiving:

other:

Reference 3

Endpoint:

adsorption / desorption, other

Remarks:

adsorption

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

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

Justification for type of information:

Please refer to the QMRF and QPRF files provided under the section attached justification.

Qualifier:

according to guideline

Guideline:

other: REACH guidance on QSAR R.6

Principles of method if other than guideline:

KOCWIN (v2.00): estimation using calculated log Kow

GLP compliance:

no

Type of method:

other: Calculation

Specific details on test material used for the study:

SMILES:

Test temperature:

25 °C

Computational methods:

- Other: log Kow used for estimation:-3.9 (calculated value, please refer to IUCLID section 4.7, the experimentally derived value was log Kow<0.3)

Key result

Type:

Koc

Value:

0 L/kg

Temp.:

25 °C

Remarks on result:

other: QSAR predicted value. The substance is not within the applicability domain of the model.

Key result

Type:

log Koc

Value:

-3.385 dimensionless

Temp.:

25 °C

Remarks on result:

other: QSAR predicted value. The substance is not within the applicability domain of the model.

CHEM  : Pentapotassium bis(peroxymonosulphate) bis(sulphate)

--------------------------- KOCWIN v2.00 Results ---------------------------

 Koc Estimate from Log Kow:

 -------------------------

        Log Kow (User entered  ) ......................... : -3.90

        Non-Corrected Log Koc (0.8679 logKow - 0.0004) ..... : -3.3852

        Fragment Correction(s) --> NONE                     :  ---

        Corrected Log Koc .................................. : -3.3852

 

                        Estimated Koc: 0.0004119 L/kg  <===========

Validity criteria fulfilled:

yes

Conclusions:

Using KOCWIN v2.00 the log KOC of the test item was calculated to be -3.3852 at 25 °C. The substance is inorganic and not within the applicability domain of the model. Thus the estimation may be less accurate.

Executive summary:

The logKoc was calculated using KOCWIN v2.00 as part of EPISuite v4.11 from US Environmental Protection Agency.

Using KOCWIN v2.00 the log Koc of the test item was calculated to be -3.3852 at 25 °C (EPI Suite, 2014).

The adequacy of a prediction depends on the following conditions:

a) the (Q)SAR model is scientifically valid: the scientific validity is established according to the OECD principles for (Q)SAR validation;

b) the (Q)SAR model is applicable to the query chemical: a (Q)SAR is applicable if the query chemical falls within the defined applicability domain of the model;

c) the (Q)SAR result is reliable: a valid (Q)SAR that is applied to a chemical falling within its applicability domain provides a reliable result;

d) the (Q)SAR model is relevant for the regulatory purpose.

 

For assessment and justification of these 4 requirements the QMRF and QPRF files were developed and attached to this study record.

 

Description of the prediction Model

The prediction model was descripted using the harmonised template for summarising and reporting key information on (Q)SAR models. For more details please refer to the attached QSAR Model Reporting Format (QMRF) file. 

 

Assessment of estimation domain

The assessment of the estimation domain was documented in the QSAR Prediction Reporting Format file (QPRF). Please refer to the attached document for the details of the prediction and the assessment of the estimation domain.

 

Description of key information

An OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC)) study was performed to determine the soil adsorption coefficient (Koc) of KMPS tripe salt. The Koc was determined to be < 18 at 20 °C and the log Koc was < 1.25.

To get a more precise result the log Koc was further calculated by a QSAR approach. Therefore, the log Koc was calculated by KOCWIN v2.00 based on the calculated log Kow (-3.9) of the substance. The following formula is used: Log Koc = 0.8679 * logKow - 0.0004, resulting in a log Koc of -3.3852.