1-[(2,4-dinitrophenyl)azo]-2-naphthol

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 February 2022 - 22 April 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: EU method A.24 (Partition coefficient (n-octanol / water), HPLC method)

Version / remarks:

2016

Deviations:

not specified

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Version / remarks:

2004

Deviations:

not specified

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7570 (Partition Coefficient, n-octanol / H2O, Estimation by Liquid Chromatography)

Version / remarks:

1996

Deviations:

not specified

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Test material

Test material information

Constituent 1

Reference substance name:

1-[(2,4-dinitrophenyl)azo]-2-naphthol

EC Number:

222-429-4

EC Name:

1-[(2,4-dinitrophenyl)azo]-2-naphthol

Cas Number:

3468-63-1

Molecular formula:

C16H10N4O5

IUPAC Name:

1-[(2,4-dinitrophenyl)diazenyl]-2-naphthol

Test material form:

solid: particulate/powder

Remarks:

orange

Specific details on test material used for the study:

Physical Description: Orange powder
Storage Conditions: At room temperature
Solubility in water: 6.3 μg/L
Solubility in octanol: 1.76 mg/L

Study design

Analytical method:

high-performance liquid chromatography

Results and discussion

Partition coefficient

Partition coefficient 1

Key result

Type:

log Pow

Partition coefficient:

4.7

Temp.:

20 °C

Remarks on result:

other: Major peak (peak area 99.5%). Neutral pH.

Partition coefficient 2

Key result

Type:

log Pow

Partition coefficient:

4.1

Temp.:

20 °C

Remarks on result:

other: Minor peak (peak area 0.5%). Neutral pH.

Details on results:

- Retention times of reference substances used for calibration: see table below
- Details of fitted regression line: log k' = 0.342 log Pow – 0.786 (r = 0.995, n= 20)
- Chromatogram and graph of regression line: see attachment
- The chromatogram of the test material in tetrahydrofuran (test solution 1) showed one major peak and one smaller peak
- The log Pow for the major peak was reported as the log Pow of the substance.
- Average retention data for the test item: see table below
- The value of log Pow obtained from duplicate measurements was within ± 0.1 log units.

Any other information on results incl. tables

Table: Results Partition coefficient n-octanol-water (HPLC method)

Substance	Retention time (min)			log Pow	Pow	Peak area (%)
	tr,1	tr,2	mean
Formamide (t0)	0.580	0.578	0.579
Benzylalcohol	0.763	0.764		1.1
Nitrobenzene	0.957	0.962		1.9
Toluene	1.576	1.570		2.7
Bromobenzene	1.646	1.645		3.0
1,4-Dichlorobenzene	2.079	2.079		3.4
Biphenyl	2.856	2.854		4.0
1,2,4-Trichlorobenzene	3.299	3.299		4.2
Dibenzyl	4.891	4.891		4.8
Triphenylamine	9.267	9.247		5.7
4,4’-DDT	13.584	13.599		6.5
Test solution 2	4.564^*	4.561^*	4.563	4.7	5.6 x 10^4	n.a.
Test solution 1 –peak 1	3.057	3.059	3.058	4.1	1.4 x 10^4	0.5
Test solution 1 –peak 2	4.550^*	4.553^*	4.552	4.7	5.5 x 10^4	99.5

n.a.  Not applicable.

^*       Retention times are comparable.

Applicant's summary and conclusion

Conclusions:

The log Pow at neutral pH and ca. 20°C for the substance (peak area of 99.5%) and impurity (peak area 0.5%) was determined to be 4.7 and 4.1, respectively. Pow was 5.5E+04 and 1.4E+04, respectively.

Executive summary:

The partition coefficient (n-octanol/water) of the substance was determined using the HPLC method. The study was performed in accordance with EC A.24, OECD 117 and OPPTS 830.7570 and in compliance with GLP. 

An UPLC-UV system was used with 75/25 (v/v) methanol/water as mobile phase and 210 nm and 476 nm as wavelength of detection for the reference substances and the substance, respectively. Based on pKa, the study was performed at neutral pH. 

Formamide was used as unretained substance. For the construction of the regression line, ten references substances (log Pow range at 20°C: 1.1 - 6.5 (OECD TG 117)) were used. Duplicate injections of the unretained substance, reference substances and test material solutions.

The chromatogram of the substance showed one major peak (99.5%) and another small peak (0.5%). Substituting the mean retention times in the regression line yielded log Pow values of 4.7 for the substance (major peak), and 4.1 for impurity. Pow= 5.5E+04 (substance) and 1.4E+04 (impurity).