Sodium p-chloro-m-cresolate

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - Shake Flask Method)

Version / remarks:

September 19, 1984

GLP compliance:

yes

Type of method:

flask method

Analytical method:

high-performance liquid chromatography

Type:

Pow

Partition coefficient:

727.66

Temp.:

21 °C

Remarks on result:

other: pH not given

Type:

log Pow

Partition coefficient:

2.86

Temp.:

21 °C

Remarks on result:

other: pH not given

Contrary to what might be expected in a salt-like compound, the test substance has a well-defined partition coefficient, i.e. it is not dependent on concentration.

Measured and individual values:

Test no.	Concentration octanol [mg/mL]	concentration water [mg/mL]	Partition coefficient individual	Partition coefficient group mean
1a	1.037095	1.384E-03	749.35	765.67
1b	1.048636	1.341E-03	781.98
2a	0.551166	0.828E-03	665.66	716.01
2b	0.529558	0.691E-03	766.36
3a	0.261072	0.359E-03	727.22	701.31
3b	0.264757	0.392E-03	675.40

Executive summary:

The partition coefficient log Pow of sodium p-chloro-m-cresolate was determined by shake flask method according to EU Method A.8 to be 2.86 at 21 °C.

Reference 2

Endpoint:

partition coefficient

Type of information:

other: This experimental data was performed on the conjugate acid, 4-chloro-3-methylphenol, the neutral form of the registration substance.

Remarks:

According to ECHA Guidance on information requirement, the Kow is typically defined as the partition coefficient of the neutral, undissociated form of a substance.

Adequacy of study:

key study

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)

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

GLP compliance:

yes (incl. QA statement)

Remarks:

Ministerium für Arbeit, Integration und Soziales des Landes Nordrhein-Westfalen, Düsseldorf, Germany

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

The test was performed with 4-chloro-3-methylphenol, the nonionic form of sodium p-chloro-m-cresolate.
99.9 % 4-chloro-3-methylphenol

Type:

log Pow

Partition coefficient:

2.73

Temp.:

25 °C

pH:

7.2

Remarks on result:

other: 4-chloro-3-methylphenol

The partition coefficient (Pow) of 4-chloro-3-methylphenol, the nonionic form of sodium p-chloro-m-cresolate, was determined according to the HPLC method at 40 °C. In order to comply with the guideline OECD 117 and considering environmental relevance, buffered water at pH 7 was chosen. The reference Pow-values in the OECD-guideline presumably refer to 25 °C. Even though the column temperature was 40 °C, this temperature is without influence on the result of the determination. The calibration was done referring to Pow-values of reference substances determined at 25 °C.

For the determination of the partition coefficient (Pow) six calibration standards with log Pow from 1.3 - 3.2 are established in Regulation EC 440/2008.

The chromatogram of the test item showed 1 signal eluting at 6.2 minutes.

For the partition coefficient of the test item determined by HPLC follows: log Pow = 2.73 at 25 °C (all validity criteria have been met).

Details on Results:

Mean value of 3 single values of the calibration substances:

Calibration items	Retention time [tr] = min	Capacity factor k’	Log k’	Log Pow
Thiourea (dead time (t0))	1.335	-	-	-
4-Methoxyphenol	2.443	0.830	- 0.081	1.3
Phenol	2.742	1.054	0.023	1.5
p-Cresol	3.491	1.614	0.023	1.9
4-Chlorophenol	4.546	2.404	0.381	2.4
1-Naphthol	6.753	4.057	0.381	2.7
4-Phenylphenol	8.666	4.057	0.793	3.2

Capacity factor: k’ = (t_R - t₀)/t₀

t_R = retention time of substances;

t₀ = dead time

Effective correlation: log k’ = a + b log Pow,

Linear regression gives:

a = - 0.64067

b = 0.44018

r = 0.9943

where, a and b = regression factor and r = correlation factor

Determined values of the test item (single values):

Test item	Retention time [tr] (min) Test 1	Retention time [tr] (min) Test 2	Retention time [tr] (min) Test 3	Standard deviation of the retention time [tr] (min)	Relative standard deviation of the retention time [tr] (%)
4-chloro-3-methylphenol	6.199	6.200	6.203	0.0021	0.03

Mean value of 3 single values of the test item:

Test item	Retention time [tr] (min)	Capacity factor k’	Log k’	Log Pow
4-chloro-3-methylphenol	6.201	3.644	0.5617	2.73

Conclusions:

For the partition coefficient of the test item 4-chloro-3-methylphenol, the nonionic form of sodium p-chloro-m-cresolate, determined by HPLC follows:
log Pow: 2.73 at 25 °C (all validity criteria have been met)

From log Pow and pKa = 9.4 following logD values can be calculated:
logD = 2.7 at pH 4
logD = 2.7 at pH 7
logD = 2.6 at pH 9

Executive summary:

The partition coefficient (Pow) of 4-chloro-3-methylphenol, the nonionic form of sodium p-chloro-m-cresolate, was determined according to the HPLC method at 40 °C. In order to comply with the guideline OECD 117 and considering environmental relevance, buffered water at pH 7 was chosen. The reference Pow-values in the OECD-guideline presumably refer to 25 °C. Even though the column temperature was 40 °C, this temperature is without influence on the result of the determination. The calibration was done referring to Pow- values of reference substances determined at 25 °C.

For the determination of the partition coefficient (Pow) six calibration standards with log Pow from 1.3 - 3.2 are established in Regulation EC 440/2008. The chromatogram of the test item 4-chloro-3-methylphenol showed 1 signal eluting at 6.2 minutes.

For the partition coefficient of the test item 4-chloro-3-methylphenol, determined by HPLC follows:

log Pow: 2.73 at 25 °C (all validity criteria have been met).

Description of key information

log Pow = 2.86 at 21 °C (EU Method A.8, shake flask)

log Pow = 2.73 at pH 7.2 and 25 °C (nonionic form) (OECD 117, HPLC method)

logD = 2.7 at pH 4

logD = 2.7 at pH 7

logD = 2.6 at pH 9

Key value for chemical safety assessment

Log Kow (Log Pow):

2.73

at the temperature of:

25 °C

Additional information

The partition coefficient log Pow of sodium p-chloro-m-cresolate was determined by shake flask method according to EU Method A.8 to be 2.86 at 21 °C, no information on pH value was given in this study.

Measurements on logPow of ionisable substances should be made in their nonionic form using an appropriate buffer with a pH below the pK for a free acid or above pK for a free base. The nonionic form of sodium p-chloro-m-cresolate is 4-chloro-3-methylphenol (the conjugate acid) and therefore in a further study a test according to OECD Guideline 117, HPLC method, was performed with 4-chloro-3-methylphenol. The pKa value of 4-chloro-3-methylphenol is pKa(acid) = 9.4. Therefore the undissociated form (nonionic form) exists at a pH value < 9.4 and the test was carried out in buffered water at pH 7. A log Pow of 2.73 at pH 7.2 and 25 °C was determined for the nonionic form.

The relevant logD values for the environmentally relevant pH values were calculated by using the pKa value and log Pow = 2.73 at 25 °C according to equation

logD = log Pow - log [1 + 10^(pH-pKa)]