2-Naphthalenesulfonic acid, 7-amino-4-hydroxy-3,8-bis[[4-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]azo]-, trisodium salt

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - HPLC Method)

Version / remarks:

The study is conducted in accordance with the following guidelines:
• OECD Guidelines for the Testing of Chemicals, Method No. 117, adopted 13. April 2004: “Partition Coefficient (n-octanol/water), High Performance Liquid Chromatog-raphy (HPLC) Method“
• Council Regulation (EC) No 440/2008 of 30. May 2008, published 31. May 2008, Method A.8 “Partition Coefficient“
• Commission Regulation (EU) 2016/266 of adopted 7 December 2015 amending Regu-lation EC No. 440/2008, Method A.24 “Partition Coefficient (N-OCTANOL/WATER), HIGH PERFORMANCELIQUID CHROMATOGRAPHY (HPLC) METHOD

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

< 0.3

Temp.:

20 °C

pH:

ca. 5.5

Key result

Type:

log Pow

Partition coefficient:

< 3.29

Temp.:

20 °C

pH:

ca. 5.5

Details on results:

The correlation log k/ log POW was used for the calculation of the log POW of the compo-nents of test item Blendazol Red Blendwell. Due to the fact that the retention time of peak 1 lay below the retention time of thiourea (log POW is not calculable) the log POW of this peaks is stated as < 0.3 (log POW of reference item with lowest retention time 2-Butanone is 0.3). The log POW of peak 2, 3 and 4 lay in the range of the reference items.
The log POW of Blendazol Red Blendwell is stated as < 0.3 – 3.29, determined at pH 5.5 therefore.  

1.1.1   Calculated Values

The calculated values are presented in the following table:

Table8.2‑c      Capacity Factor, log Capacity Factor, log P_OWof Test Item Peaks

Peak	Measurement No.	k	log k	log POW
1	1	-0.1649	n.c.*	n.c.*
	2	-0.1648	n.c.*	n.c.*
	3	-0.1731	n.c.*	n.c.*
	Mean			n.c.*
	Standard Deviation			n.c.*
2	1	0.8546	-0.0683	1.544
	2	0.8486	-0.0713	1.537
	3	0.8437	-0.0738	1.531
	Mean			1.537
	Standard Deviation			0.007
3	1	2.6044	0.4157	2.723
	2	2.6002	0.4150	2.721
	3	2.5851	0.4125	2.715
	Mean			2.719
	Standard Deviation			0.004
4	1	4.4788	0.6512	3.296
	2	4.4569	0.6490	3.291
	3	4.4281	0.6462	3.284
	Mean			3.290
	Standard Deviation			0.006

*Not calculable, because k is negative. The retention time of peak 1 is lower than the retention time of thiourea, which was used for the determination of the dead time of the method.

 

log P_OWwas calculated from the capacity factor as follows:

 

log P_OW= (log k + 0.7024) / 0.4107

Conclusions:

The test item chromatogram showed one large and three small peaks.
Although area is not necessarily correlated to absolute concentration if a UV detector is used, it is assumed that the test item consists mainly of peak 1 and of peak 4. As peaks 2 and 3 showed a relative area < 5 %, they were considered as minor peaks.
The correlation log k / log POW was used for the calculation of the log POW of the compo-nents of test item Blendazol Red Blendwell. Due to the fact that the retention time of peak 1 lay below the retention time of thiourea (log POW is not calculable) the log POW of this peak is stated as < 0.3 (log POW of reference item with lowest retention time 2-Butanone is 0.3). The log POW of peak 2, 3 and 4 lay in the range of the reference items.
The log POW of Blendazol Red Blendwell is stated as < 0.3 – 3.29 (mean), determined at pH 5.5 therefore.

Executive summary:

The partition coefficient was determined using the HPLC method according to the EU A.8 test guideline , The partition coefficient was determined in triplicate, at 20˚C and pH 5.5 obtaining a value (log Pow)

as < 0.3– 3.29 therefore

Description of key information

Summary -Results

Peak	Area [mAU*min][1]	Relative Area [%]	Retention Time [min]	log POW ±Standard Deviation
1	5.6362	88.30	1.226	n.c.*
2	0.1923	3.01	2.722	1.537 ± 0.007
3	0.0468	0.73	5.295	2.719 ± 0.004
4	0.5081	7.96	8.030	3.290 ± 0.006

[1]mAU = milli absorbance units

Because the test item is ionisable, this study was conducted at pH 5.5 by usage of mobile phase, adjusted to pH 5.5.

Blendazol Red Blendwell is a salt and is charged 3 fold permanently. At pH range 4.5 – 6.5 Blendazol Red Blendwell is estimated to be charged 3fold mainly (≥ 90%). Therefore the determination was performed using mobile phase, adjusted to pH 5.5 to ensure a defined pH value.

The correlation log k/log P_OWis good: the coefficient of determination r²was calculated with 0.956. This value was considered as sufficiently high to use the calibration function for the determination of the log P_OW of the test itemBlendazol Red Blendwell.

The test item chromatogram showed one large and three small peaks.

Although area is not necessarily correlated to absolute concentration if a UV detector is used, it is assumed that the test item consists mainly of peak 1 and of peak 4. As peaks 2 and 3 showed a relative area < 5 %, they were considered as minor peaks.

Using the correlation log k / log P_OW, the log P_OWof three of four components of test itemBlendazol Red Blendwell was calculated:the log P_OWof peak 1 was not calculable, because its retention time lay below the retention time of thiourea. The reason for this lower retention time may be, that a charged molecule is repelled by unmodified silanole groups of the HPLC column material and elute for the dead time therefore.The log P_OWof this peak is stated as < 0.3 (log P_OWof reference item with lowest retention time 2-Butanone is 0.3)

As peaks 2 and 3 showed a relative area < 5 %, they were considered as minor peaks.

The log P_OWof Blendazol Red Blendwellis stated as < 0.3 and 3.29 therefore

Key value for chemical safety assessment

Log Kow (Log Pow):

0.3

at the temperature of:

25 °C