Bisguanidinium phosphate

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

other: expert statement

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: expert statement

Justification for type of information:

The results of the study performed on guanidinium phosphate can be used in the same way for bisguanidinium phosphate due to the structural similarity of both substances. Guanidinium phosphate is a 1:1 salt of guanidin and phosphoric acid and diguanidinium phosphate is the 2:1 salt of guanidin and phosphoric acid. Therefore the only difference in the structure of the substance is the ratio between guanidine and phosphoric acid.

With this argument the study performed on guanidinium phosphate for determination of the partition coefficient is entered below as study for bisguanidinium phosphate.

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Version / remarks:

(2008)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

(1995)

Deviations:

no

GLP compliance:

no

Type of method:

shake-flask method to: flask method

Partition coefficient type:

octanol-water

Analytical method:

other: Ion Chromatography (see Section 8)

Type:

Pow

Partition coefficient:

< 0

Temp.:

25 °C

pH:

>= 5.21 - <= 5.78

Remarks on result:

other: Mean (n=6). Standard deviation: 0.00022

Type:

log Pow

Partition coefficient:

< -3.48

Temp.:

25 °C

pH:

>= 5.21 - <= 5.78

Remarks on result:

other: Mean (n=6).

Details on results:

No analyte was detected in the n-octanol layer extracts therefore the limit of detection (LOD) for the applied method, 0.5 mg/L, was used as the nominal concentration in the octanol layers. Therefore the calculated average logP value is likely to be lower than -3.48.

The determined values of the partition coefficient expressed as their common logarithms fall within a range of +/- 0.3 log units as noted in the test guidelines and therefore test accuracy is acceptable. Considering the recoveries the deviations are in the range of 94-102%.

Calculation of partition coefficient (Pow and log Pow) for test substance*:

*concentration of test substance in n-octanol phase has been considered to be equal to LOD = 0.5 mg/L.

	Test 1A	Test 1B	Test 2A	Test 2B	Test 3A	Test 3B
Weight of sample (mg)	26.766	26.766	17.844	17.844	4.461	4.461
Amount of substance in n-octanol phase (mg)	0.0045	0.0045	0.0030	0.0030	0.0060	0.0060
Conc. in water phase (mg/L)	7.54350	7.31300	7.75850	7.81000	3.87800	3.87500
Conc. in water phase x dilution (mg/L)	1508.7000	1462.6000	775.8500	781.0000	387.8000	387.5000
Amount of substance in water phase (mg)	27.1566	26.3268	18.6204	18.7440	4.6536	4.6500
Recovery (mg)	27.1611	26.3313	18.6234	18.7470	4.6596	4.6560
P = conc. in n-octanol / conc. in water	0.00017	0.00017	0.00032	0.00032	0.00064	0.00065
Mean P values	0.00017		0.00032		0.00065
Mean P for all determinations	0.00038
Standard deviation of individual p from the mean p value	0.00022
log P	-3.770	-3.770	-3.495	-3.495	-3.194	-3.187
Mean log P value	-3.48
pH of aqueous layer	5.24	5.21	5.42	5.39	5.78	5.77

Conclusions:

The partition coefficient (n-octanol/water) (log Pow) of the substance at pH = 5.21 - 5.78 and 25 °C was determined to be < -3.48.

Executive summary:

The partition coefficient (n-octanol/water) (log Pow) of the substance at pH = 5.21 - 5.78 and 25 °C was determined not under GLP conditions to be < -3.48 by using the shake flask method in accordance with EC A.8 and OECD 107 guidelines.

Description of key information

The partition coefficient (n-octanol/water) (log Pow) of the substance at 25 °C was determined to be < -3.48 by using the shake flask method in accordance with EC A.8 and OECD 107 guidelines. 

Key value for chemical safety assessment

Log Kow (Log Pow):

-3.48

at the temperature of:

25 °C

Additional information

Key value for CSA: log Pow < -3.48 at 25 °C. pH of the aqueous layer: 5.21 - 5.78. The same value will be used for the guanidine part of the salt in the preparation of the CSA for guanidinium phosphate.