Hydrogen bis[1-[(5-chloro-2-hydroxyphenyl)azo]-2-naphtholato(2-)]chromate(1-)

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 December 2017 - 16 December 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Version / remarks:

27 July 1995

Deviations:

yes

Remarks:

methodological limitations, e.g. no motivation for selected stock conc. (no preliminary test), no justification buffer use, overall mass balance has not been addressed, inconsistent analytical procedures, insufficient reporting of measured conc.

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Partition coefficient type:

octanol-water

Test material

Test material information

Constituent 1

Reference substance name:

Hydrogen bis[1-[(5-chloro-2-hydroxyphenyl)azo]-2-naphtholato(2-)]chromate(1-)

EC Number:

250-774-0

EC Name:

Hydrogen bis[1-[(5-chloro-2-hydroxyphenyl)azo]-2-naphtholato(2-)]chromate(1-)

Cas Number:

31714-55-3

Molecular formula:

C32H19Cl2CrN4O4

IUPAC Name:

[1-{[5-chloro-2-(hydroxy-kappaO)phenyl]diazenyl}-2-naphtholato(2-)-kappaO]{1-[(5-chloro-2-hydroxyphenyl)diazenyl]-2-naphtholato-kappaO}chromium

Test material form:

solid: particulate/powder

Details on test material:

- Appearance: Black powder
- Storage conditions: At room temperature

Study design

Analytical method:

high-performance liquid chromatography

Results and discussion

Partition coefficient

Key result

Type:

log Pow

Partition coefficient:

> 4

pH:

ca. 7

Remarks on result:

other: just an indication due to analytical inconsistencies (a.o. different end-solutions of test samples)

Details on results:

- The analysed concentration in the test item n-octanol stock solution was 5124.604 mg/L
- There was no test item related peak observed in the chromatograms of the water phases of all three ratios of (n-octanol/water) analysis. An accurate calculation of the partition coefficient could therefore not be performed due to the very low solubility of the test item in buffer water.
- Therefore, an estimation was made based on measured concentrations in the n-octanol phases and the LOD of the method used to measure the buffer solutions. The LOD (determined from the signal to noise ratio (S/N) in chromatogram of the lowest linearity standard solution during buffer solution analysis) was 0.11 mg/L; thus the solubility of the substance in buffer pH 7 was concluded to be < 0.11 mg/L.

The Pow of the substance was calculated to be > 10660 (mean, n=6). This corresponds with a Log Pow of > 4.0.

Any other information on results incl. tables

Concentration of T-95/T-99 in Phases

Ratio of Solvents (n-Octanol: Water)	Repli-cation	N° of Injection	Peak Area in Phases Y			Dilution Factor of Phases D		Concentration (mg/L) of T-95/T-99in Phases X
			n-Octanol	Water		n-Octanol	Water	n-Octanol	Mean	Water	Mean
1 : 1	R1	I	404392	ND		100	1.0	1410.745	1441.693	NA	NA
		II	420920	ND				1472.640		NA
	R2	I	456992	ND				1607.724	1582.739	NA	NA
		II	443648	ND				1557.753		NA
1 : 2	R1	I	229995	ND		100	1.0	757.655	758.020	NA	NA
		II	230190	ND				758.385		NA
	R2	I	252010	ND				840.098	838.533	NA	NA
		II	251174	ND				836.967		NA
2 : 1	R1	I	357641	ND		100	1.0	1235.670	1237.574	NA	NA
		II	358658	ND				1239.478		NA
	R2	I	341512	ND				1175.269	1176.780	NA	NA
		II	342319	ND				1178.291		NA
Intercept with Y-axis (a)				27675.55*			Slope of the line (b)*			26703.37*
Typical Calculation
Concentration (mg/L) [X] Y - a =      -------- x D b					404392– 27675.55 = --------------------------- x 100 26703.37   = 1401.745mg/L

Estimation of Pow and log Pow based on reported measured octanol concentrations and reported water solubility

ratio	Mean meas. Octanol conc. [mg/L]		Solubility in buffer pH 7 [mg/L]		Pow	log Pow	mean log Pow
1:1	1441,693		< 0,11		> 13106	> 4,12	> 4,14
	1582,739		< 0,11		> 14388	> 4,16
1:2	758,02		< 0,11		> 6891	> 3,84	> 3,86
	838,533		< 0,11		> 7623	> 3,88
2:1	1237,574		< 0,11		> 11251	> 4,05	> 4,04
	1176,78		< 0,11		> 10698	> 4,03
mean Pow					> 10660
log Pow (from mean Pow)					> 4,028

Applicant's summary and conclusion

Conclusions:

The log Pow of T-95/T-99 was estimated to be >4.0, based on measured concentrations in the n-octanol phases and the derived value for solubility in buffer pH 7 (i.e. < 0.11 mg/L, based on LOD).

Executive summary:

A study was performed according to OECD guideline 107 and GLP principles, to determine the partition coefficient (n-octanol/water) of T-95/T-99.

The test item had a low solubility in buffer pH 7 and therefore the log Pow was estimated based on measured concentrations in the n-octanol phases and the derived value for solubility in buffer pH 7 (i.e. < 0.11 mg/L, based on LOD). The resulting log Pow is >4.0.

This value is only an indication for the octanol-water partition coefficient as the analytical procedure to determine test substance concentrations in test samples showed major inconsistencies.