diethyl pyridine-2,4-dicarboxylate

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From July 14, 2015 to September 29, 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

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

Test guideline 2

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))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Media:

other:

Test material

Test material information

Constituent 1

Reference substance name:

MEXORYL SBU

IUPAC Name:

MEXORYL SBU

Constituent 2

Reference substance name:

diethyl pyridine-2,4-dicarboxylate

EC Number:

680-341-5

Cas Number:

41438-38-4

Molecular formula:

C11H13N04

IUPAC Name:

diethyl pyridine-2,4-dicarboxylate

Radiolabelling:

no

Study design

Test temperature:

25°C

HPLC method

Details on study design: HPLC method:

EQUIPMENT- Apparatus: A high performance liquid chromatograph with an UV-VIS detector was used. The detection wavelength depended on the characteristics of the test item and the reference items - Type, material and dimension of analytical (guard) column: LiChrospher 100 CN (250*4 mm, 5 µm). The stationary phase was a cyanopropyl phase- Detection system: UV-Detector:225 nmMOBILE PHASES- Type: 55% methanol / 45% 0.01 M citrate-buffer solution pH 5.5 - Experiments with additives carried out on separate columns: no- pH: 5.5- Solutes for dissolving test and reference substances: methanolDETERMINATION OF DEAD TIME- Method: by inert substances which are not retained by the columnREFERENCE SUBSTANCES- Identity:Six chemicals for which log Koc has been reported were used to calibrate the elution time in units of log Koc. Structurally heterogeneous reference items were chosen: Methyl benzoate, Pyrazophos, Acetanilide, Linuron, 1,2,3 Trichlorobenzene, Diclofop-methylDETERMINATION OF RETENTION TIMES- Quantity of test substance introduced in the column: Prior weighting the test item was melted in a water bath at ca. 35°C (ca. 1 hour). Afterwards 50.15 mg of the test item (liquid) was dissolved and filled up to 50 mL using ethanol. For application the stock solution was diluted in mobile phase to obtain standard solutions at the concentration of 10 and 100 mg/L. - Quantity of reference substances: A stock solution of each reference compound was prepared by dissolution of the reference item in methanol. Appropriate volumes of the stock solutions were diluted using methanol to prepare standard solutions of these compounds at concentration of 50 mg/L. In addition, defined volumes of each of the stock solutions were diluted with methanol to prepare a reference item mixture.Sodium nitrate was used as inert substance (not retained by the column) to determine the dead time. A stock solution of the compound was prepared by dissolution in pure water (1000 mg/L). This stock solution was diluted with pure water and was injected three times to determine the dead time t0 (t0 = retention time of the unretarded component).- Intervals of calibration: Each reference item was injected separately to the HPLC system to determine the individual retention time of the compounds under test conditions. Subsequently the inert substance was injected two times and a mixed solution of the reference items was injected once. Thereafter, the test item was injected. The low concentration was injected once, the high concentration was injected three times. After the analysis of the test item solution the mixed solution of the reference compounds was injected two times again followed by injection of the inert substance once. The retention times of the reference compounds and the test item were determined, permitting the calculation of the capacity factor k'. EVALUATION- Calculation of capacity factors k': The capacity factor was calculated from the retention of the substance concerned (tr) and the unretarded component (t0):k' = (tr_t0)/t0where: tr = retention time of the test item [min]t0 = time a non-sorbed chemical needs to pass the column (dead time) [min]k' = capacity factor- Calculation of retention times: mean value of three measurements.- Determination of the log Koc value: The adsorption coefficient Koc was determined based on a calibration curve using 6 reference items. Calibration curve pH 5.5:y = 0.1999 * x – 0.2718, regression coefficient r² = 0.9930

Results and discussion

Adsorption coefficient

Key result

Type:

log Koc

Value:

1.5 dimensionless

Temp.:

25 °C

Remarks on result:

other: Estimated at pH 5.5

Results: HPLC method

Details on results (HPLC method):

- Retention times of reference substances used for calibration: see below- Details of fitted regression line (log k' vs. log Koc): y(log k') = 0.1999x (log Koc) - 0.2718 ; regression coefficient r² = 0.9930The linearity of the method was proved in the log Koc-range from 1.25 to 4.20. - Graph of regression line: see attached- Average retention data for test substance: mean value: 3.46 mn; capacity factor: 1.08, log k':0.03, logKoc: 1.5

Any other information on results incl. tables

Item	Nb of analysis	Retention times [min]*	Capacity factor^1	Log k’^1	Log Koc^2
Sodium nitrate (=dead time)	3	1.67	n.a.	n.a.	n.a.
Methyl benzoate	3	3.69	1.22	0.08	1.80
Pyrazophos	3	6.40	2.84	0.45	3.65
Acetanilide	3	3.20	0.92	-0.04	1.25
Linuron	3	4.87	1.92	0.28	2.59
1,2,3 Trichlorobenzene	3	5.39	2.23	0.35	3.16
Diclofop-methyl	3	7.75	3.65	0.56	4.20

n.a. not applicable

1 values represent rounded results calculated from the exact raw data

2 log Koc values as given in the reference

* mean value of three measurements

Item	Replicate N°	Retention times [min]	Capacity factor^1	Log k’^1	Log Koc^2
Mexoryl SBU	1	3.463	1.08	0.03	1.5
Mexoryl SBU	2	3.464	1.08	0.03	1.5
Mexoryl SBU	3	3.463	1.08	0.03	1.5
Mean value		3.46	1.08	0.03	1.5

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Determinations run in triplicate. The values of of log K oc derived from individual measurements were within a range of 0.25 log unit.

Conclusions:

The adsorption coefficient Koc was determined based on a calibration curve using 6 reference items. Calibration curve pH 5.5: y = 0.1999 * x – 0.2718, regression coefficient r² = 0.9930The linearity of the method was proved in the log Koc-range from 1.25 to 4.20. Log Koc (estimated, at pH 5.5): 1.5

Executive summary:

Estimation of the Adsorption Coefficient (Koc) by HPLC method [OECD 121 and Commission Regulation (EC) No.440/2008, Annex, C.19] was determined on the test item MEXORYL SBU, following GLP. The logKoc was determined at pH 5.5. Buffer solutions were used to stabilize the pH. Based on calibration curves obtained by correlation of the retention time of 6 structurally heterogeneous reference items with their known adsorption coefficient, the log Koc of the test item MEXORYL SBU was estimated to be 1.5 at pH 5.5.