Benzene, 1,1'-oxybis[methyl-, sulfonated, ammonium salts

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24 January - 30 January 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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

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

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Test temperature:

25°C

Details on study design: HPLC method:

EQUIPMENT
HPLC system:
Pump VWR-Hitachi Chromaster 5160
Autosampler VWR-Hitachi Chromaster 5260 AS
UV Detector VWR-Hitachi Chromaster 5420
Column Agilent, Zorbax CN, 150 x 4.6 mm; 5 µm
Conditions The experiment was run at 25°C and for detection a wavelength of 210 nm and 254 nm were used. Determination of the respective retention time was performed at 210 nm for the test item, Sodium nitrate and 1,2,3-Trichlorobenzene and at 254 nm for Acetanilide, Methyl benzoate, Naphthalene, Pyrazophos and Phenanthrene.

MOBILE PHASES
- Type: The mobile phase was aqueous, 10 mM citrate buffer:methanol (45:55; v:v) at pH 6.5±0.1. This buffer system and pH was chosen to ensure stable pH conditions in the middle of the pH range of 5.5 to 7.5 as given in the guideline. In this range, the sulfo groups of the various test item components should be deprotonated and thus singly negatively charged, as their pKa is typically much lower than the pH range given above. Isocratic conditions with a flow rate of 1 ml/min were applied.
- Solutes for dissolving test and reference substances:
Stock solutions of the test item and of the reference items were prepared in in a suitable solvent (For more details see any other information on materials and methods incl. tables). All stock solutions were diluted by a factor of 100 using the mobile phase, for the single as well as the mixed injections.

DETERMINATION OF DEAD TIME
The dead time (t0) was determined with Sodium nitrate, which is unretained under the applied conditions.

REFERENCE SUBSTANCES
see any other information on materials and methods incl. tables

DETERMINATION OF RETENTION TIMES
The Software EZChrom Elite 3.3.2 SP2, Agilent Technologies was used to analyse retention times.
- Quantity of test substance / reference substances introduced in the column:
Stock solutions of the test item and of the reference items were prepared in in a suitable solvent (For more details see any other information on materials and methods incl. tables). All stock solutions were diluted by a factor of 100 using the mobile phase, for the single as well as the mixed injections. The injection volume was 10 µl.

MEASUREMENTS / REPETITIONS
- Number of determinations: 2
The selected set of reference items was used to conduct two determinations of log KOC. First, the reference items were injected individually to identify them via their retention time. Secondly, the reference items were injected as a mixture of all of them together to calibrate the system followed by two injections of the single test item solution. Finally, the reference items were again injected as a mixture to re-confirm the initial calibration.
The first test item injection was evaluated using the initial calibration with the mixed reference items solution and the second test item injection was evaluated using the second calibration with the mixed reference items solution.

EVALUATION
- Calculation of capacity factors k': k = (tR - t0) / t0 with tR = retention time, t0 dead time
The calculation was done using the program Microsoft Excel.

- Calculation of retention times: Retention times were analysed with the software EZChrom Elite.

- Determination of the log Koc value:
With the determined k values of the reference items a correlation between log k versus log KOC was plotted in Microsoft Excel with a subsequent linear regression analysis

Key result

Sample No.:

#1

Type:

log Koc

Value:

ca. 1.25 - <= 3.71 dimensionless

pH:

6.5

Temp.:

25 °C

Remarks on result:

other: see remarks field

Remarks:

LogKoc is given as a range between the first and last test item peak. logKoc of the first peak: log KOC is given as <1.25, i.e. less than the one of Acetanilide, which was the first eluting reference item. logKoc of the last peak: 95% confidence limits: 3.54–3.88

Details on results (HPLC method):

see details in field any other information on results incl. tables

- Retention times of Sodium nitrate (dead time): 1.39 min (three determinations)

- Retention times of reference substances used for calibration:

Item	First determination retention time (min)	Second determination retention time (min)
Acetanilide	2.65	2.66
Methyl benzoate	3.51	3.51
Napthalene	6.03	6.03
1,2,3 -Trichlorobenzene	7.07	7.07
Pyrazophos	10.57	10.57
Phenanthrene	12.19	12.20
First test item peak	1.15	1.15
Last test item peak	10.32	10.33

- First test item peak:

The first test item related peak eluted at 1.15 min, which is before the dead time of 1.39 min determined using Sodium nitrate. It was therefore not possible, to extrapolate its log KOC based on the regression data obtained by the injection of the reference items. Instead, its log KOC is given as <1.25, i.e. less than the one of Acetanilide, which was the first eluting reference item.

- Details of fitted regression line (log k' vs. log Koc):

	First injection	Second injection
Coefficient of regression (r^2)	0.992	0.992
Intercept (A)	1.299	1.295
Slope (B)	2.98	2.98

- Graph of regression line attached (see attached background material)

- Retention times for test substance:

	First determination retention time (min)	Second determination retention time (min)
Last test item peak	3.71 (95% confidence interval 3.54 -3.88)	3.71 (95% confidence interval 3.54 -3.88)

Validity criteria fulfilled:

yes

Conclusions:

In this study according to OECD guideline 121, the log KOC values of test item Benzene, 1,1’-oxybis(methyl-, sulfonated, ammonium salt (ca 50% ) (CAS no. of main component 75314-26-0), calculated as the mean of both determinations, is <1.25 to 3.71 corresponding to a KOC range of <17.8 to 5103 at pH 6.5.

Executive summary:

The log KOC of the test item Benzene, 1,1’-oxybis(methyl-, sulfonated, ammonium salt (ca 50% ) (CAS no. of main component 75314-26-0) was determined according to TG OECD 121. This determination is based upon a regression analysis of the log KOC values of reference items against their respective retention times as determined by HPLC analysis.

The following reference items were used: Acetanilide, Methyl benzoate, Naphthalene, 1,2,3-Trichlorobenzene, Pyrazophos and Phenanthrene. The dead time of the HPLC system was determined with Sodium nitrate. This set of reference items yielded a calibration with log KOC values ranging from 1.25 to 4.09 and retention times ranging from 2.65 min to 12.2 min. The dead time of the HPLC system was 1.39 min.

The test item “Benzene, 1,1’-oxybis(methyl-, sulfonated, ammonium salt (ca 50% )” is a complex mixture of monomer until pentamer, which present one or two sulfo groups and each type of substance presents several isomer forms. Therefore, the log KOC is given as a range, which is based on the evaluation of the first and the last test item peak found in the corresponding chromatogram.

The first test item related peak eluted before the dead time determined using Sodium nitrate. It was therefore not possible, to extrapolate its log KOC based on the regression data obtained by the injection of the reference items. Instead, its log KOC is given as <1.25, i.e. less than the one of Acetanilide, which was the first eluting reference item.

The log KOC value for the last test item peak with the highest retention time was determined to be 3.71 (95% confidence limits: 3.54–3.88) in the first as well as the second determination.

Consequently, the log KOC range for the test item Benzene, 1,1’-oxybis(methyl-, sulfonated, ammonium salt (ca 50% ) (CAS no. of main component 75314-26-0), calculated as the mean of both determinations, is <1.25 to 3.71 corresponding to a KOC range of <17.8 to 5103 at pH 6.5.

Description of key information

The log KOC of Benzene, 1,1’-oxybis(methyl-, sulfonated, ammonium salt (ca 50% ) (CAS no. of main component 75314-26-0) was determined in a GLP study according to TG OECD 121 (Tobler, N, 2018).

The log KOC, as range between the first and last test item peak, is <1.25 to 3.71 corresponding to a KOC range of <17.8 to 5103 at pH 6.5.

The determinations are valid since the values of log KOC derived from the two repeated measurements fall within a range of 0.25 log units.

Key value for chemical safety assessment

Koc at 20 °C:

2 560

Additional information

An average Koc of 2560 (arithmetic mean of minimum and maximum Koc) for the UVCB substance was used for chemical safety assessment.

The following reference items were used: Acetanilide, Methyl benzoate, Naphthalene, 1,2,3-

Trichlorobenzene, Pyrazophos and Phenanthrene. The dead time of the HPLC system was determined with Sodium

nitrate.

With the determined k values of the reference items a correlation between log k versus log KOC was plotted in Microsoft Excel with a subsequent linear regression analysis.

As key value the KOC of the first test item peak was chosen: 17.8. Only a "smaller than" value could be obtained.

The KOC was determined at 25°C. It was assumed that the KOC at 20°C is in the same range.