Diammonium phthalate

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was conducted between 10 June 2005 and 11 August 2005

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2005

Report date:

2005

Materials and methods

Test guideline

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))

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC estimation method

Test material

Test material information

Constituent 1

Reference substance name:

Diammonium phthalate

EC Number:

208-341-9

EC Name:

Diammonium phthalate

Cas Number:

523-24-0

Molecular formula:

C8H6O4.2H3N

IUPAC Name:

diammonium phthalate

Test material form:

solid: crystalline

Specific details on test material used for the study:

Description: white crystalline solid
Lot number: 4172005
Date recieved: 02 June 2005
Storage conditions: room temperature, in the dark

Radiolabelling:

no

Study design

Test temperature:

30°C

HPLC method

Details on study design: HPLC method:

EQUIPMENT
- Apparatus:
HPLC system: Agilent Technologies 1100, incorporating autosampler and workstation
Column: Genesis CN 120A 4 μm (250 x 4.6 mm id)
Column temperature: 30°C
Flow-rate: 1 ml/min
UV detector wavelength: dead time and reference standards: 210 nm
sample: 228 nm

MOBILE PHASES
- Type: methanol:reverse osmosis water (55:45 v/v) adjusted to pH 7 .0 with 0.1 M hydrochloric acid and approximately 0.1% pH 7 buffer solution*
- pH: approzimately neutral
- Solutes for dissolving test and reference substances: reverse osmoisis water and methanol for test and reference substances respectively

* pH 7 buffer solution composition: disodium hydrogen orthophosphate (0.03 M), potassium dihydrogen orthophosphate (0.02 M) and sodium chloride (0.02 M)

DETERMINATION OF DEAD TIME
- Method: The dead time was determined by measuring the retention time of formamide (purity
>99.5%, 765 mg/I solution in methanol).

REFERENCE SUBSTANCES
- Identity:
Acetanilide
Phenol
Isoproturon
Triadimenol
Linuron
Naphthalene
Endosulfan-diol
Fenthion
a-Endosulfan
Phenanthrene
Diclofop-methyl
DDT

DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 10 μl
- Quantity of reference substances: 10 μl


REPETITIONS
- Number of determinations: 2

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Type:

log Koc

Value:

< 1.25 dimensionless

pH:

7

Temp.:

30 °C

Remarks on result:

other: phthalate component

Adsorption coefficient 2

Type:

log Koc

Value:

< 1.25 dimensionless

pH:

7

Temp.:

30 °C

Remarks on result:

other: ammonium component

Results: HPLC method

Details on results (HPLC method):

Adsorption coefficient of sample
The retention times, capacity factors and log10 Koc values determined for the sample are shown in the following table:
Injection Retention time (mins) Capacity Factor (k) Log10k Log10koc
1 1.807 < 0.213 < -0.671 < 1.25
2 1.809 < 0.213 < -0.671 < 1.25


Mean log10 Koc: < 1.25
Adsorption coefficient: < 17.8

Discussion
The method guideline states that the measurement of adsorption coefficient should be carried out on substances in their ionised and unionised forms. However, the dissociation constants of certain functional groups found in the test material made it impossible to satisfy this criteria. Testing would be required at pH 3 or below and at greater than pH 11 for the acidic and basic functional groups respectively. As a consequence of this, one of the functional groups will always be present in its ionised form. Therefore, as these pHs are outside the environmental pH range for this test and also experimentally impractical, testing was carried out at approximately neutral pH with both functional groups ionised.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficients (Koc) of components of the test material have been determined. The results are shown in the following table:

Component Log10Koc Koc
Phthalate < 1.25 < 17.8
ammonium < 1.25 < 17.8

Executive summary:

The adsorption coefficients (Koc) of the components of the test material were determined using the HPLC screening method, Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001. Thre results are as follows:

Component	Log10Koc	Koc
Phthalate	< 1.25	< 17.8
ammonium	< 1.25	< 17.8