Ethoprophos

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 2000-07-28 to 2000-08-18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Test material

Test material information

Constituent 1

Reference substance name:

Ethoprophos

EC Number:

236-152-1

EC Name:

Ethoprophos

Cas Number:

13194-48-4

Molecular formula:

C8H19O2PS2

IUPAC Name:

ethyl bis(propylsulfanyl)phosphinate

Test material form:

liquid

Study design

Analytical method:

high-performance liquid chromatography

Results and discussion

Partition coefficient

Key result

Type:

log Pow

Partition coefficient:

2.99

Temp.:

35 °C

Remarks on result:

other: pH not reported

Any other information on results incl. tables

RESULTS

The quantities of each calibration and test substance injected onto the column and their appropriate purities and literature values are given in Table 1. The calibration, statistical and analytical data are shown in Table 2.

 

Table 1:

Compound	Purity (%)	Lit. value (log Pow)	Mass injected (µg)
Formamide	>99	N/A	6.89
Acetophenone	Min 99	1.7	0.25
Methyl benzoate	99	2.1	0.31
Ethyl benzoate	>99	2.6	0.38
1 ,4-dichlorobenzene	>99	3.4	0.56
Biphenyl	NS	4.0	0.26
Phenanthrene	NS	4.5	0.27
Test substances	N/A	N/A	6.33

NS - data not supplied

N/A - not appropriate

 

DISCUSSION AND CONCLUSION

The Test substances eluted as a single peak with a retention time which was within the range of retention times of the calibration substances. Therefore, the results of the estimation may be expected to be realistic, as the results were calculated by interpolation rather than extrapolation. It was possible to establish the calibration line with six different calibration compounds, three eluting before the test compound and three after.

There were only minimal differences between the replicates of retention times for each of the calibration and test substances, and between the two injection sequences. The resultant calculated values differed only to a small extent, therefore the results may be considered as acceptable for regulatory purposes.

The partition coefficient of Ethoprop was successfully evaluated using the HPLC simulation technique with a mobile phase of methanol/water, 75/25 v/v. The test substance eluted as a single component exhibiting a retention time corresponding to a log Pow value of +2.99 and which was within a 95% confidence range of +2.9 to +3.1.

 

Table 2

CALIBRATION DATA

Calibration Substance	First estimation		Second estimation
	Retention time (min)	Capacity Factor (log K)	Retention time (min)	Capacity Factor (log K)
Formamide	2.893	N/A	2.889	N/A
Acetophenone	4.200	-0.345	4.189	-0.347
Methyl benzoate	5.069	-0.124	5.054	-0.125
Ethyl benzoate	6.056	0.039	6.045	0.038
1 ,4-dichlorobenzene	9.562	0.363	9.552	0.363
Biphenyl	12.776	0.534	12.762	0.534
Phenanthrene	18.583	0.734	18.580	0.735

 

 

STATISTICAL DATA

Slope:	0.3740	0.3748
Intercept:	-0.9406	-0.9437
Correlation (R2):	0.9950	0.9950

 

 

ANALYTICAL DATA

Compound		Retention time (min)	Log K	log Pow
				Mean	95 % min	95 % max
First estimation with Test substance
Injection 1	7.258	Mean
Injection 2	7.262	7.260	0.179	2.99	2.89	3.09
Back-calculated calibration compound (log Pow = 2.6)
Ethyl benzoate		6.045	0.038	2.62	2.51	2.72
Second estimation with Test substance
Injection 1	7.262	Mean
Injection 2	7.240	7.251	0.179	2.99	2.90	3.09
Back-calculated calibration compound (log Pow = 2.6)
Ethyl benzoate		6.045	0.038	2.62	2.51	2.72

 

Applicant's summary and conclusion

Conclusions:

The log Pow was determined to be 2.99.

Executive summary:

This study was performed to provide data for the n-octanol:water partition coefficient of purified Test substances in accordance with EEC guideline AS, OECD Guideline 117 and OPPTS 830.7570 by the HPLC simulation method.

The partition coefficient was found to be:
log Pow = 2.99, within a 95% confidence range of 2.9 to 3.1