Benzenamine, reaction products with aniline hydrochloride and nitrobenzene

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:

2 August 2006 - 8 December 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP 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.

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

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/sewage sludge

Test temperature:

Column temperature: 30 °C

Details on study design: HPLC method:

Preparation of sample solution
Test material (0.0246 g) was diluted to 100 mL with acetonitrile.

Preparation of reference solutions
The dead time was determined by measuring the retention time of formamide (purity* 99.5%, 731 mg/l solution in mobile phase).
Solutions of reference standards were prepared in methanol:

Standard Purity (%)* Concentration (mg/l)
Acetanilide ~99 103
Phenol 99.99 109
Atrazine 97.4 111
Isoproturon 99.8 101
Triadimenol 98.5 99
Linuron 99.00 101
Naphthalene 99.00 108
Endosulfan-diol 99.8 102
ot-Endosulfan 99.6 107
Phenanthrene 97.00 103
Dielofop-methyl 99.00 106
DDT 98.00 108

* value quoted by Supplier

Determination of retention time
The sample, formarnide and reference standard solutions were injected in duplicate using the following HPLC parameters:

HPLC System: Agilent Technologies 1050, incorporating autosampler and workstation
Column: Zorbax SB-CN (250 x 4.6 mm id)
Column temperature: 30°C
Mobile phase: acetonitrile:water (75:25 v/v)
pH of mobile phase: 7.5, obtained using 1M sodium hydroxide
Flow-rate: 1.0 ml/min
UV detector wavelength: dead time and reference standards: 210 nm; sample: 291 nm
Injection volume: 10 µl

As a number of the test material components had a very high affinity for the HPLC column stationary phase, it was necessary to amend the mobile phase composition to 100% acetonitrile to successfully elute them. This was performed by means of a gradient program at a time greater than that of the retention time of the highest calibration standard, DDT. Therefore all components eluted with the amended mobile phase shared a common adsorption coefficient value, that of a log10 Koc greater than 5.63.

Construction of calibration curve
A calibration curve was constructed from the retention time data of the formamide and reference standard solutions. The capacity factors (k) for the reference standards were calculated using the equation below.

Adsorption coefficient of sample
The capacity factor was calculated using the equation below and the log10 Koc value determined with reference to the calibration curve.

Calculation
The capacity factor was determined using the following equation:

k = (tr - t0) / t0

where:
k = capacity factor
tr = retention time (min)
t0 = dead time (min)

Type:

Koc

Value:

6.94 - 427 000

Temp.:

30 °C

Type:

log Koc

Value:

0.842 - 5.63

Temp.:

30 °C

Details on results (HPLC method):

The method guideline states that the determination of adsorption coefficient should be performed on substances in their ionised and un-ionised forms. From information supplied by the Sponsor, the dissociation constants of the amine functional groups within the cyclic structure were estimated to be 6.19 and 6.57. No other dissociation constants within the environmentally relevant pH range applicable to the test method, 5.5 to 7.5, were identified. The definitive test was therefore performed at a nominal pH of 7.5, that at which ionisation of the test material was minimised, in an attempt to assess the un-ionised forms of the test material components whilst maintaining the test pH within the valid range of the method.
However, no further determination was performed at a pH below that of the estimated dissociation constants of the test material as cationic substances have been demonstrated to interact with the HPLC column stationary phase by mechanisms other than partitioning. Therefore the estimation of the adsorption coefficient of ionised substances from the capacity factor of reference substances of known log10 Koc values is not considered valid. This was concluded not to impact on the validity of the study, as irrespective of an anticipated increased water solubility and reduced partition coefficient value, the mobility of substances in soil is typically reduced on formation of a cationic state due to strong secondary ionic interactions with clay particles and other ion exchange sites within the soil. Therefore, the identification of components within the test material with an adsorption coefficient in excess of that of the highest calibration standard was considered to remain valid at all environmentally relevant pH's.

Validity criteria fulfilled:

yes

Conclusions:

The adsorption coefficient (Koc) of the test material has been determined to be 6.94 to greater than 4.27 x 10^5, log10 Koc 0.842 to greater than 5.63. By percentage area normalisation, 61.4% of the test material has a log10 Koc greater than 5.63.

Executive summary:

In a general physico-chemical properties study (0370/0351), the adsorption coefficient (Koc) of the substance was found to be between 6.94 and greater than 4.27 x 10⁵, log₁₀Koc 0.842 to >5.63, using the HPLC screening method, Method C19 of Commission Directive 2001/59/EC and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001.

By percentage area normalisation, 61.4% of the test material has a log₁₀Koc greater than 5.63.

Description of key information

The adsorption coefficient (Koc) of the test material has been determined to be 6.94 to greater than 4.27 x 10^5, log10 Koc 0.842 to greater than 5.63.  By percentage area normalisation, 61.4% of the test material has a log10 Koc greater than 5.63.

Additional information

In a general physico-chemical properties study (0370/0351), the adsorption coefficient (Koc) of the test material was found to be between 6.94 and greater than 4.27 x 10^5, log10Koc 0.842 to >5.63, using the HPLC screening method, Method C19 of Commission Directive 2001/59/EC and Method 121 of the OECD Guidelines for Testing of Chemicals, 22 January 2001. By percentage area normalisation, 61.4 % of the test material has a log10Koc greater than 5.63. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).