[4-[p,p'-bis(dimethylamino)benzhydrylidene]cyclohexa-2,5-dien-1-ylidene]dimethylammonium m-[[p-anilinophenyl]azo]benzenesulphonate

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 2019-05-24 to 2019-06-04

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)

Version / remarks:

2006

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

slow-stirring method

Partition coefficient type:

octanol-water

Analytical method:

liquid chromatography

mass spectrometry

Key result

Type:

log Pow

Partition coefficient:

ca. 2.807

Temp.:

25 °C

pH:

ca. 6.2

Details on results:

Validity criteria and results:
- Repeatability: the mean log Pow values in the equilibration time for each replicate (test vessel) with four sub replicates (samples) falls within a range of ± 0.3 log units (≤ 0.1 log in the study)
- Temperature: the T°C in the study falls within the 25 +/- 1°C requirement (25.03 ± 0.03 for replicate 1; 25.06 ± 0.05 for replicate 2 and 25.07 ± 0.08 for replicate 3).

Sampling was performed in time intervals of at least 5 h until equilibrium was reached, meaning a regression of the n-octanol / water concentration ratio (the log P_OWvalue) against time over a time span of 4 time points yielding a slope that is not significantly different from zero (determined by the software GraphPad Prism 5).

 

Mass Balance in n‑Octanol‑ and Aqueous Phase

 

Sampling interval	Nominal mass^1) [mg]	Repl.	Meas. conc. in n‑octanol [mg/L]	Mass in n‑octanol [mg]	Meas. conc. in aq. Phase [mg/L]	Mass in aq. Phase [mg]	Sum mass [mg]	RR [%]
1	1.377	1	25.3	1.26	0.0390	0.0722	1.33	97
		2	23.8	1.19	0.0385	0.0712	1.26	92
		3	24.7	1.23	0.0408	0.0755	1.31	95
2	1.377	1	24.0	1.20	0.0360	0.0666	1.27	92
		2	23.7	1.18	0.0373	0.0689	1.25	91
		3	23.5	1.18	0.0398	0.0736	1.25	91
3	1.377	1	24.0	1.20	0.0362	0.0670	1.27	92
		2	25.3	1.26	0.0415	0.0768	1.34	97
		3	23.6	1.18	0.0376	0.0696	1.25	91
4	1.377	1	25.0	1.25	0.0361	0.0668	1.32	96
		2	24.4	1.22	0.0381	0.0705	1.29	94
		3	24.6	1.23	0.0367	0.0678	1.30	94

1)  = Based on the measured concentration of the stock solution at test start

Repl. = Replicate

Meas. conc.    = Measured concentration, dilution factors taken into account

aq. phase = Aqueous phase

RR  = Recovery rate, related to the nominal mass

 

 

 

Partition Coefficient Results

 

Replicate	Mean Test	Measured concentration		POW	Log POW
number	Duration [h]	in n-octanol [mg/L]	in aq. Phase [mg/L]		Single	Mean	SD ±	CV
1	71.81	25.3	0.0390	647	2.811	2.824	0.012	0.43
	76.96	24.0	0.0360	668	2.825
	95.48	24.0	0.0362	664	2.822
	101.70	25.0	0.0361	692	2.840
2	71.81	23.8	0.0385	618	2.791	2.797	0.010	0.37
	76.96	23.7	0.0373	636	2.803
	95.48	25.3	0.0415	609	2.785
	101.70	24.4	0.0381	641	2.807
3	71.81	24.7	0.0408	605	2.782	2.795	0.024	0.85
	76.96	23.5	0.0398	592	2.772
	95.48	23.6	0.0376	628	2.798
	101.70	24.6	0.0367	670	2.826
Mean value						2.805
log POW,Av						2.807
slog POW,Av						0.021

 aq. phase = Aqueous phase

P_OW = Partition coefficient (n-octanol / water)

Log P_OW = Decadic logarithm of the partition coefficient (n-octanol / water)

SD = Standard deviation

CV = Coefficient of variation [%]

log P_OW,Av  = Weighted average value of log P_OW

s_{log POW,Av}  = Weighted standard deviation

 

 

Conclusions:

The partition coefficient of the test item was determined to be 2.807 +/-0.021 (25 +/- 1°C; mean pH 6.2)

Executive summary:

The determination of the partition coefficient (n-octanol/water) of the test item was performed according to OECD 123 (2006) according to the OECD guideline 123 for Testing Chemicals (2006).

The study was performed in compliance with GLP.

The partition coefficient was determined employing the slow-stirring method at 25 +/-1°C from 3 independent replicates (test vessels) with 4 sub-replicates each.

A weighted average mean value was calculated according to the guideline. The pH-value of the aqueous phase was determined by a pH-meter at the end of the experimental phase.

 

Analytical evaluation was performed using LC-MS/MS on a reversed phase analytical column using the test item for external calibration. The analytical method was validated with satisfactory results regarding linearity, limits of quantification and detection, accuracy, precision and specificity.

 

The partition coefficient of the substance was determined to be of 2.807 +/- 0.021 (25 +/- 1°C; mean pH 6.2).

Description of key information

Partition coefficient (slow stirring method), according to OECD TG 203.

Key value for chemical safety assessment

Log Kow (Log Pow):

2.807

at the temperature of:

25 °C

Additional information

The log Pow was experimentally determined according to the slow stirring method (OECD TG 123).