Acetylcysteine

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-02-28 to 2018-09-11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7550 (Partition Coefficient, n-octanol / H2O, Shake Flask Method)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

-0.6

Temp.:

23 °C

pH:

>= 2.7 - <= 2.8

Preliminary Test

The preliminary test at room temperature showed, that the 1-octanol solubility of the test item was in the range of 9.5 g/L and 12.7 g/L.With the water solubility of 62.9 to 167.6 g/L the partition coefficient can be estimated to be between -0.7 and -1.2. For the determination of the log Pow in this range the shake flask method is recommended.

 

Main Test

The phases of the shake-flask-method were measured twice by means of HPLC.

 

Concentrations in the aqueous phases

separating funnel	pH values	measured concentration (mg/L)	mean concentration (mg/L)
1a	2.8	486.8 / 483.8	970.6
1b	2.8	489.2 / 489.0	978.1
2a	2.8	442.6 / 446.1	888.7
2b	2.8	440.4 / 434.1	874.5
3a	2.7	687.1 / 685.3	1372.4
3b	2.7	689.3 / 695.7	1385.0

 

Concentrations in the octanol phases

separating funnel	measured concentration (mg/L)	mean concentration (mg/L)
1a	262.7 / 265.1	263.9
1b	264.8 / 265.1	264.9
2a	229.4 / 230.9	230.2
2b	230.7 / 231.9	231.3
3a	407.2 / 406.5	406.9
3b	403.1 / 405.8	404.4

 

Results of the shake-flask-method

 

separating funnel	total amount of test item in the separating funnel (mg)	recovery rate (%)	POW	log POW
1a	44.10	93	0.272	-0.6
1b	44.42	94	0.271	-0.6
2a	44.75	95	0.259	-0.6
2b	44.23	94	0.265	-0.6
3a	43.72	93	0.296	-0.5
3b	43.88	93	0.292	-0.5
mean value				-0.6
standard deviation				<0.1

 

Conclusions:

The partition coefficient of the test item was determined at 23 °C to be log Pow = -0.6.

Executive summary:

A study was conducted in accordance with OECD TG 107 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance using the shake flask method. The equilibrium concentration of the test item in both phases was determined by means of HPLC.After adding the different amounts of stock solution, pre-saturated double distilled water and pre-saturated 1-octanol, the funnels were shaken for approx. 10 minutes in a shaking apparatus. After shaking the phases were allowed to separate in the funnels. Subsequently, 10 mL of each phase were centrifuged for 30 minutes at 20 °C and 15000 rpm. For the analytical measurement by means of HPLC the centrifuged clear water phases were diluted from 0.5 mL to 1 mL with double distilled water. The centrifuged clear 1-octanol phases were measured without dilution. The pH values of all water phases were measured. The phases of the shake-flask-method were measured twice. The partition coefficient of the test item as determined at 23 °C (pH 2.7 – 2.8) to be logPow = -0.6. 

Description of key information

The partition coefficient of the test item was determined at 23 °C to be log Pow = -0.6.

Key value for chemical safety assessment

Log Kow (Log Pow):

-0.6

at the temperature of:

23 °C

Additional information

A study was conducted in accordance with OECD TG 107 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance using the shake flask method. The equilibrium concentration of the test item in both phases was determined by means of HPLC.After adding the different amounts of stock solution, pre-saturated double distilled water and pre-saturated 1-octanol, the funnels were shaken for approx. 10 minutes in a shaking apparatus. After shaking the phases were allowed to separate in the funnels. Subsequently, 10 mL of each phase were centrifuged for 30 minutes at 20 °C and 15000 rpm. For the analytical measurement by means of HPLC the centrifuged clear water phases were diluted from 0.5 mL to 1 mL with double distilled water. The centrifuged clear 1-octanol phases were measured without dilution. The pH values of all water phases were measured. The phases of the shake-flask-method were measured twice. The partition coefficient of the test item as determined at 23 °C (pH 2.7 – 2.8) to be logPow = -0.6 (reference 4.7 -1).