Calcium 3-hydroxy-4-[(1-sulphonato-2-naphthyl)azo]-2-naphthoate

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 04 Aug 2017 to 08 Dec 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Version / remarks:

2008

Deviations:

no

Test guideline 2

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))

Version / remarks:

2001

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil

Test material

Test material information

Constituent 1

Reference substance name:

Calcium 3-hydroxy-4-[(1-sulphonato-2-naphthyl)azo]-2-naphthoate

EC Number:

229-142-3

EC Name:

Calcium 3-hydroxy-4-[(1-sulphonato-2-naphthyl)azo]-2-naphthoate

Cas Number:

6417-83-0

Molecular formula:

C21H12N2O6S.Ca

IUPAC Name:

calcium 3-hydroxy-4-[(1-sulfonato-2-naphthyl)diazenyl]-2-naphthoate

Test material form:

solid: particulate/powder

Details on test material:

Appearance: red powder
Test item storage: at room temperature

Radiolabelling:

no

Study design

Test temperature:

Column temperature: 35°C ± 1°C

HPLC method

Details on study design: HPLC method:

HPLC CONDITIONS
- Apparatus: Acquity UPLC system (Waters, USA)
- Column: Acquity UPLC HSS Cyano, 100 mm x 2.1 mm i.d., dp = 1.8 µm (Waters)
- Injection volume: 5 μL

PDA DETECTION
- Detector: Acquity UPLC PDA (Waters)
- UV detection at 210 nm (Reference substance)
- UV detection at 236 nm (Test item and blank)

MOBILE PHASE
- The test item is a salt. There is not a pH at which both the cationic and anionic part of the test item are in their non-ionised form. Therefore an unbuffered mobile phase was used.
- Composition: 55/45 (v/v) methanol/water
- Flow: 0.4 mL/min

REFERENCE ITEM
- Identity: Acetanilide (log Koc 1.26 according to OECD 121 based on soil adsorption data).
- A solution of the reference item was prepared in 55/45 (v/v) methanol/water from a stock solution (ca. 1 g/L) in methanol.

TEST ITEM
A 10.0 mg/L test item solution was prepared in dimethyl sulfoxide from a stock solution (1000 mg/L) in dimethyl sulfoxide.

DETERMINATION OF RETENTION TIMES
- Duplicate injections of the reference substance and test item.
- Single or duplicate injection of the blank solutions.

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Key result

Type:

log Koc

Value:

< 1.26 dimensionless

Temp.:

20 °C

Remarks on result:

other: unbuffered mobile phase

Adsorption coefficient 2

Key result

Type:

Koc

Value:

< 18.2 L/kg

Temp.:

20 °C

Remarks on result:

other: unbuffered mobile phase

Results: HPLC method

Details on results (HPLC method):

Mean retention time of the reference item: 0.842 minutes
Mean retention time of the test item: 0.405 minutes

Applicant's summary and conclusion

Conclusions:

The log Koc of the substance at neutral pH was estimated to be < 1.26 (Koc < 18.2).

Executive summary:

The HPLC estimation method was used for the determination of the adsorption coefficient (Koc) of the substance. The study was performed in accordance with EC C.19 and OECD 121 and in compliance with GLP. The mobile phase was 55/45 (v/v) methanol/water. One reference item was used: Acetanilide (log Koc 1.26 based on soil-adsorption reference data). The wavelength of detection was 210 nm for the reference item and 236 nm for the test item. The stationary phase contained cyanopropyl chains chemically bonded to silica. Duplicate injections of the test item and reference substance. Mean retention time of reference item was 0.842 minutes. Mean retention time of the test item was 0.405 minutes. From this it was concluded that the log Koc of the substance is < 1.26 (Koc < 18.2).