p-benzoquinone dioxime

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06-03-2018 to 06-04-2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study performed under GLP. All relevant validity criteria were met.

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)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7570 (Partition Coefficient, n-octanol / H2O, Estimation by Liquid Chromatography)

Deviations:

no

GLP compliance:

yes

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

0.3

Temp.:

35 °C

pH:

7

Type:

Pow

Partition coefficient:

1.9

Temp.:

35 °C

pH:

7

HPLC method

The results of the HPLC method are given in the Table 2. The calibration curve of the log k’ of the reference substances as function of log Pow had an regression line represented by the equation: log k’ = 0.465 × log Pow – 0.693 (r = 0.998, n = 14).

 

Table 2. Pow of the substance

Substance	Retention time (min)			log Pow	Pow
	tr,1	tr,2	mean
Formamide (t0)	0.582	0.583	0.583
2-Butanone	0.740	0.739	0.740	0.3
Benzylalcohol	0.964	0.964	0.964	1.1
Nitrobenzene	1.431	1.430	1.431	1.9
Toluene	3.148	3.143	3.146	2.7
1,4-Dichlorobenzene	5.245	5.233	5.239	3.4
Biphenyl	9.028	9.008	9.018	4.0
1,2,4-Trichlorobenzene	10.149	10.129	10.139	4.2
Test item	0.741	0.740	0.741	0.3	1.9

Conclusions:

The partition coefficient of the test item was determined to be Pow = 1.9 and log Pow = 0.3 at 35 °C and pH 7.0

Executive summary:

The n-octanol/water partition coefficient was determined using the HPLC method within OECD TG 117, EU Method A.8 and US EPA OPPTS 830.7570 in accordance with GLP. A 1000 mg/L stock solution of the test substance was prepared in methanol. The stock solution was 100-fold diluted to obtain an end solution of 60/40 (v/v) methanol/water. The final concentration of the test substance solution was 10.0 mg/L injected at 5 µL into mobile phase of 60/40 (v/v) methanol/water. Samples of the test item were analysed via HPLC on a C18 column with PDA UV/visible wavelength detector at 210 nm. Calibration was performed using seven reference items with known log POW values (given by the guidelines). The dead time (t0) of the HPLC system was determined with Formamide. The dead time and the reference items were measured in duplicate. The test item was injected and measured in duplicate. One individual partition coefficient value for one major chromatographic resolved test item signals was derived. The partition coefficient of the test item was determined to be log Pow 0.3 at a mean temperature 30±1°C and approximately neutral pH.

Description of key information

log Pow (HPLC) = 0.3 at 35 °C and pH 7.0, OECD TG 117, 2018

Key value for chemical safety assessment

Log Kow (Log Pow):

0.3

at the temperature of:

35 °C

Additional information

The n-octanol/water partition coefficient was determined using the HPLC method within OECD TG 117, EU Method A.8 and US EPA OPPTS 830.7570 in accordance with GLP. A 1000 mg/L stock solution of the test substance was prepared in methanol. The stock solution was 100-fold diluted to obtain an end solution of 60/40 (v/v) methanol/water. The final concentration of the test substance solution was 10.0 mg/L injected at 5 µL into mobile phase of 60/40 (v/v) methanol/water. Samples of the test item were analysed via HPLC on a C18 column with PDA UV/visible wavelength detector at 210 nm. Calibration was performed using seven reference items with known log POW values (given by the guidelines). The dead time (t0) of the HPLC system was determined with Formamide. The dead time and the reference items were measured in duplicate. The test item was injected and measured in duplicate. One individual partition coefficient value for one major chromatographic resolved test item signals was derived. According to the guidelines, the determination of the Pow of the test item should be performed in its non-ionized form. Therefore, the pKa values of the test item were calculated using the Perrin calculation method (pKalc 5.0, module in Pallas 3.0, CompuDrug International). The test item had no relevant acidc or basic groups by analysis of the test item pKa. Based on the calculations, it was decided to perform the test at neutral pH. The partition coefficient of the test item was determined to be log Pow 0.3 at a mean temperature 30±1°C and approximately neutral pH.