potassium 4-iodo-2-sulfonato-benzoic acid

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study according to OECD/EU guideline

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Materials and methods

Test guideline

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))

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

soil/sewage sludge

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

426-620-5

EC Name:

-

Cas Number:

619297-89-1

Molecular formula:

C7H4IO5S.K

IUPAC Name:

potassium 2-carboxy-5-iodobenzene-1-sulfonate

Radiolabelling:

no

Study design

HPLC method

Details on study design: HPLC method:

EQUIPMENT
Agilent HPLC system with autosampler G1329A, pump G1312A and
column oven G1316A, UV/VIS detector G1314A;
Software Chromeleon Vers. 6.70, Fa. Dionex

MOBILE PHASES
Material: stainless steel (Bischoff)
dimensions: 250 x 4.0 mm
stationary phase: Zorbax CN, 5 jam
column temperature: 25°C

DETERMINATION OF DEAD TIME
The dead time was determined by simultaneous injection of the n-alkyl methyl ketones.
Using the slope and the intercept, t0 can be calculated from a linear regression.

EVALUATION
The HPLC method is based on the correlation of the retention of a substance on a reversed
phase column packed with a commercially available cyanopropyl solid phase containing
lipophilic and polar moieties and of the adsorption coefficient K0clog
KOC = a + bxlog k' (1)

k' = (tR-to)/to (capacity factor) with
tR retention time of substances
t0 dead time

The dead time is determined by using a homologous series of n-alkyl methyl ketones.
For the calibration according to equation retention times of selected reference
compounds with known adsorption coefficients were measured. In a further step the log K0c
of the test item was derived from its retention time.

Batch equilibrium or other method

Analytical monitoring:

yes

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Type:

log Koc

Value:

0.8

Temp.:

25 °C

Remarks on result:

other: pH 1.2

Adsorption coefficient 2

Type:

log Koc

Value:

0.2

Temp.:

25 °C

Remarks on result:

other: pH 2

Adsorption coefficient 3

Type:

log Koc

Value:

-3.5

Temp.:

25 °C

Remarks on result:

other: pH 7

Adsorption coefficient 4

Type:

Koc

Value:

6.3

Temp.:

25 °C

Remarks on result:

other: pH 1.2

Adsorption coefficient 5

Type:

Koc

Value:

1.6

Temp.:

25 °C

Remarks on result:

other: pH 2

Adsorption coefficient 6

Type:

Koc

Value:

0

Temp.:

25 °C

Remarks on result:

other: pH 7

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Executive summary:

The adsorption coefficients (Koc) of 4 -lodo-2 -potassiumsulfonatobenzoic acid were determined according to OECD 121 guideline and EEC-guideline 2001/59/EEC C.19.

Nine calibration substances were injected into an HPLC-system under the same analytical conditions (column temperature 25°C) as for the test item (repeat determination). Calibration curves were created by using the measured retention times (log k'-values) and the known log k'values of the calibration substances for linear regression. Due to the fact that the test item is an ionisable substance, the tests were performed with both the ionized and the non-ionized form in appropriate pH ranges.

The adsorption coefficients (Koc) of 4 -lodo-2 -potassiumsulfonatobenzoic acid were determined at 25 °C:

	pH 1.2	pH2	pH7
log Koc	0.8	0.2	-3.5
Koc	6.3	1.6	0.0003