N,N'-1,4-phenylenebis[3-oxobutyramide]

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Recent study according to guideline under GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

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))

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))

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:

N,N'-1,4-phenylenebis[3-oxobutyramide]

EC Number:

246-438-8

EC Name:

N,N'-1,4-phenylenebis[3-oxobutyramide]

Cas Number:

24731-73-5

Molecular formula:

C14H16N2O4

IUPAC Name:

3-oxo-N-[4-(3-oxobutanamido)phenyl]butanamide

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
Batch No.: INTH040016

Radiolabelling:

no

Study design

Test temperature:

30°C

HPLC method

Details on study design: HPLC method:

PRINCIPLES OF THE METHOD
HPLC is performed on analytical columns packed with a commercially available cyanopropyl solid phase containing lipophilic and polar moieties. A moderately polar stationary phase based on a silica matrix is used:
- 0 - Si - CH2 - CH2 - CH2 - - CN
silica ; non-polar spacer polar moiety
The principle of the test method is similar to that of the EEC-Guideline A.8. While passing through the column along with the mobile phase the test item iriteracts with the stationary phase. As a result of partitioning between mobile and stationary phases the test item is retarded. The dual-composition of the stationary phase having polar and non-polar sites allows for interaction of polar and non-polar groups of a molecule in a similar way as is the case for organic matter in soil or sewage sludge matrices. This enables the relationship between the retention time on the column and the adsorption coefficient on organic matter to be established.
pH has a significant influence on sorption behaviour in particular for polar substances. For agricultural soils or tanks of sewage treatment plants pH normally varies between pH 5.5 and 7.5. For ionizable substances, two tests should be performed with both ionised and non-ionised forms in appropriate buffer solutions but only in cases where at least 10 % of the test compound will be dissociated within pH 5.5 to 7.5.
Since only the relationship between the retention on the HPLC column and the adsorption coefficient is employed for the evaluation, no quantitative analytical method is required and only the determination of the retention time is necessary. If a suitable set of reference materials is available and standard experimental conditions can be used, the method provides a fast and efficient way to estimate the adsorption coefficient Koc.
The HPLC method is applicable to chemical substances for which an appropriate detection system (e.g. spectrophotometer, radioactivity detector) is available and which are sufficiently stable during the duration of the experiment. lt may be particularly useful for chemicals which are difficult to study in other experimental systems (i.e. volatile substances; substances which are not soluble in water at a concentration which can be measured analytically; substances with a high affinity to the surface of incubation systems). The method can be used for mixtures, which give unresolved elution bands. In such a case, upper and lower limits of the log K values of the compounds of the test mixture should be stated.
The method is not applicable for substances which react either with the eluent or the stationary phase. lt is also not applicable for substances that interact in a specific way with inorganic components (e.g. formation of cluster complexes with clay minerals). The method may not work for surface active substances, inorganic compounds and moderate or strong organic acids and bases. Log Koc values ranging from 1.5 to 5.0 can be determined. lonisable substances must be measured using a buffered mobile phase, but care has to be taken to avoid precipitation of buffer components or test item.
4.2. DEFINITION AND UNITS
Kd: Distribution coefficient is defined as the ratio of equilibrium concentrations C of a dissolved test item in a two phase system consisting of a sorbent (soil or sewage sludge) and an aqueous phase; it is a dimensionless value if concentrations in both phases are expressed on a weight/weight base. In case the concentration in the water phase is given on a weight/volume base the dimension then is mL•* g-1. Kd can vary with sorbent properties and can be concentration dependent.
Csoil Csludge
Kd = ------- or ----------
Cwater Cwater
where: Csoil = concentration of substance in soil at equilibrium (µg•g-1)
Csludge= concentration of substance in sludge at equilibrium (µg '1)
Cwater= concentration of substance in water at equilibrium (µg«g-I ; µg•m1-1)
Kf: Freundlich adsorption coefficient is defined as the concentration of the test item in soil or sewage sludge ()dm) when the equilibrium concentration Cwater in the aqueous phase is equal to one; dimension is µg•g sorbent. The value can vary with sorbent properties.
X 1
log --- = log Kf + - -- • log Cwater
m n
where: x/m = amount of test item (pg) adsorbed on amount of sorbent m (g) at equilibrium
1/n = slope of sorption isotherm
Cwater concentration of test item in aqueous phase at equilibrium (µg/ml)
x
At Cwater = 1; log Kf = log ----
m
Koc: Distribution coefficient (Kd) or Freundlich adsorption coefficient (Kf) normalized to the organic carbon content (foc) of a sorbent; particularly for non-ionised chemicals, it is an approximate indicator for the extent of adsorption between a substance and the sorbent and allows comparisons to be made between different chemicals. Depending on the dimensions of Kd and Kf, K, can be dimensionless or have the dimensions ml/g or µg/g organic matter.

Koc = Kd/foc (dimensionless or ml/g) or Kf/foc (µg/g)

The relationship between K, and Kd is not always linear and thus Koc values can vary from soil to soil but their variability is greatly reduced compared to Kd or Kf values.
The adsorption coefficient (Koc) is deduced from the capacity factor (k') using a calibration plot of log k' versus log Koc, of the selected reference materials.
tR-to
k' = -----
to
Where: tR = HPLC retention time of test item and reference material (minutes)
to = HPLC dead time (minutes)
QUALITY CRITERIA
ACCURACY
Normally, the adsorption coefficient of a test item can be estimated to within +/- 0.5 log unit of the value determined by the batch equilibrium method. Higher accuracy may be achieved if the reference materials used are structurally related to the test item.
REPEATABILITY
Determinations should be run at least in duplicate. The values of log Koc, derived from individual measurements should be within a range of 0.25 log unit.
REPRODUCIBILITY
Experience gained so far in the application of the method is supportive of its validity. An investigation of the HPLC method, using 48 substances (mostly pesticides) for which reliable data on Koc on soils were available gave a correlation coefficient of R = 0.95.

Results and discussion

Adsorption coefficient

Type:

log Koc

Value:

1.2

Temp.:

30 °C

Applicant's summary and conclusion

Executive summary:

SUMMARY

The adsorption coefficient (log K_oc) of Bis-acetoacetic-p-phenylenediamine was estimated according to EC-Guideline 2001/59/EC - C.19 (HPLC-method) and in accordance with the OECD-Guideline for the testing of chemicals No 121. Therefore eleven reference materials were injected into a HPLC­system under the same analytical conditions as the test item.

A calibration curve was created by linear regression using the measured retention times (log k'-values) and the known log Koc-values of the reference materials which are listed in the guideline.

The measured log k'-value of the test item was within the calibrated k'-range of reference materials.

From the calibration curve the log Koc of the test item was interpolated.

The estimated adsorption coefficient (log Koc) of
Bis-acetoacetic-p-phenylenediamine was
log K_oc= 1.2