Myo-Inositol, hexakis(dihydrogen phosphate), dodecasodium salt

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

04.04.2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Guideline study is required by REACH regulation 1907/2006

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

OECD Guidelines for the Testing of Chemicals, Method No. 117, adopted 13. April 2004: “Partition Coefficient (n-octanol/water), High Performance Liquid Chromatog-raphy (HPLC) Method“

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Method A.24 “Partition Coefficient (N-OCTANOL/WATER), HIGH PERFORMANCE-LIQUID CHROMATOGRAPHY (HPLC) METHOD

Version / remarks:

Commission Regulation (EU) 2016/266 of adopted 7 December 2015 amending Regu-lation EC No. 440/2008,

Deviations:

no

Principles of method if other than guideline:

This study was performed in order to estimate the partition coefficient log POW of the test item using HPLC. The partition coefficient (POW) is defined as the ratio of the equilibrium concentrations of a
dissolved substance in a two-phase system consisting of two largely immiscible solvents (n-octanol and water). The log POW is a key parameter in studies of the environmental fate of chemical substances. A highly significant relationship between the POW of non-ionised form of substances and their bioaccumulation in fish has been shown. It has also been shown that POW is a useful parameter in the prediction of adsorption on soil and sediments and for
establishing quantitative structure-activity relationships for a wide range of biological effects. The HPLC method covers log POW in the range of 0 to 6. Reverse phase HPLC is performed
on analytical columns packed with a commercially available solid phase containing long hydrocarbon chains (e.g. C8, C18) chemically bound onto silica.
A test item injected on such a column partitions between the mobile solvent phase and the hydrocarbon stationary phase as it is transported along the column by the mobile phase.
The test items are retained in proportion to their hydrocarbon-water partition coefficient, with hydrophilic chemicals eluted first and lipophilic chemicals last. The retention times of the peaks of the test item are compared with retention times of reference substances with known hydrocarbon-water partition coefficients.
Because the test item is ionisable, this study was conducted at pH 5 by usage of mobile phase, adjusted to pH 5. The test item is a salt and will show different ionisation states dependent of the pH value. The ionisation state of the test item was estimated using non-GLP software ACD/I-Lab 2.0: At pH range 3.7 – 5.5 the test item is estimated to be charged 6fold mainly (≥ 90%). Therefore, the determination was performed using a mobile phase, adjusted to pH 5 to ensure a defined pH value.
Experimental data (retention times of peaks of the test item and of the reference items) are used together with literature values for the log POW of the reference items to calculate the log POW for the test item.

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 585542
- Expiration date of the lot/batch: May 2019
- Purity test date: May 2016

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

< 0.3

Temp.:

25 °C

pH:

5

Remarks on result:

other: based on conclusion

Details on results:

The test item consists of the peaks 1 and 2. The two peaks lie within the dead time of the method and not within the range of log POWs of the reference items. Therefore, the corre-sponding log POW should be stated as < 0.3 for peaks 1 and 2. It is thus concluded that the test item has a log POW of < 0.3.

Calculated Values

The calculated values are presented in the following table:

Table    Capacity Factor, log Capacity Factor, log P_OW Test Item Peaks

Peak	Measurement No.	k	log k	log POW
1	1	-0.1580	n.c.*	n.c.*
	2	-0.1580	n.c.*	n.c.*
	3	-0.1602	n.c.*	n.c.*
	Mean			n.c.*
	Standard Deviation			n.c.*
2	1	-0.0427	n.c.*	n.c.*
	2	-0.0450	n.c.*	n.c.*
	3	-0.0450	n.c.*	n.c.*
	Mean			n.c.*
	Standard Deviation			n.c.*

* Not calculable, because k is negative. The retention time of the peak is lower than the retention time of thiourea, which was used for the determination of the dead time of the method.

The log P_OW of the test item peaks could not be calculated, because the retention times of the peaks are lower than the retention time of thiourea, which was used for the determination of the dead time of the method.

Therefore, the corresponding log P_OWs are stated as < 0.3 (the log P_OW of the reference with the lowest log P_OW 2-Butanone) for peaks 1 and 2 (the log P_OW of the reference with the lowest log P_OW 2-Butanone). It is thus concluded that the test item has a log P_OWof < 0.3.

Conclusions:

The test item has a log POW of < 0.3 (OECD 117 resp. EU A. 24)

Executive summary:

The aim of the study performed according to OECD 117 resp. EU A. 24 was to determine the log P_OW for the test substance. The study was performed using a HPLC with a C18 column. Six reference items with different retention times and thiourea for the determination of the dead time were used to produce a calibration curve, since retention time on hydrophobic columns and P_OW are correlated. The reference items were chosen based on the results of the pre-test. For the evaluation of the chromatograms of the reference mix the UV-signals were used. For the evaluation of the chromatograms of the test item the RI-signals were used. The values observed for the test substance are the means ± standard deviations of three independent determinations

Variations in the retention times of reference items and test item are very small. Therefore a stable configuration of the HPLC-column can be assumed.

The correlation log k/log P_OW is good: the coefficient of determination r²was calculated with 0.959. This value was considered as sufficiently high to use the calibration function for the determination of the log P_OW of the test item.

The test item consists of two peaks, which lie within the dead time of the method and not within the range of log P_OWs of the reference items. Therefore, the corresponding log P_OWs should be stated as < 0.3 for peaks 1 and 2. It is thus concluded that the test item has a log P_OWof < 0.3.

No observations were made which might cause doubts concerning the validity of the study outcome.

The two peaks lie within the dead time of the method and not within the range of log P_OWs of the reference items. Therefore, the corresponding log P_OWs are stated as < 0.3 (the log P_OW of the reference with the lowest log P_OW2-Butanone) for peaks 1 and 2. It is thus concluded that the test item has a log P_OW of < 0.3.

Description of key information

The test substance has a log POW of < 0.3 (OECD 117 resp. EU A. 24)

Additional information

The test substance has a log POW of < 0.3 at 25 ± 0.5 °C (OECD 117 resp. EU A. 24)