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Water solubility

Administrative data

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 - 22 May 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

see “Any other information on materials and methods incl. tables”

GLP compliance:

no

Type of method:

flask method

Test material

Test material information

Constituent 1

Reference substance name:

Vapour grown graphitic carbon fibre

Molecular formula:

C

IUPAC Name:

Vapour grown graphitic carbon fibre

Results and discussion

Water solubility

Water solubility:

< 1 mg/L

Incubation duration:

>= 24 - <= 72 h

Temp.:

20 °C

pH:

>= 5.4 - <= 6.6

Remarks on result:

other: Determined based on the total organic carbon (TOC) measurement.

Remarks:

Both the total carbon (TC) and the inorganic carbon (IC) of the tested samples were below the limit of quantification (1 mgC/L). Therefore, the TOC and the concentration of the test item in water could not be calculated.

Any other information on results incl. tables

Measurement of Test Temperature

The test temperatures in the incubator at the start and end of equilibration were shown in following table.

Stirring period (day)	Temperature (°C)
	At the start of equilibrium	At the end of equilibrium
1	20.2	19.9
2	20.4	20.2
3	20.2	20.1

 

 

pH Measurement

The pH measurement results for soluble fraction samples were shown in following table.

Stirring period (day)	Sample	pH
1	1D-Blank	5.8
	1D-1	6.1
	1D-2	6.6
	1D-3	6.4
2	2D-Blank	5.5
	2D-1	5.4
	2D-2	5.6
	2D-3	5.6
3	3D-Blank	5.9
	3D-1	5.8
	3D-2	6.1
	3D-3	5.8

 

 

TC, IC and TOC in blank sample and soluble fraction

The results of TC, IC and TOC in blank sample and soluble fraction are shown in the following tables.

 

Test substance concentrations in blank sample:

Stirring period (day)	Sample	TC		IC		TOC concentration (mgC/L)
		Area	Concentration (mgC/L)	Area	Concentration (mgC/L)
1	1D-Blank	1.7043	(0.6165)*	7.9077	(0.2199)**	--***
2	2D-Blank	2.7933	1.3442	7.1907	(0.1977)**	--***
3	3D-Blank	3.0680	1.4346	9.2157	(0.2574)**	--***

*: Measured TC concentration was below the lower limit of quantification (< 1 mgC/L).

**: Measured IC concentration was below the lower limit of quantification (< 1 mgC/L).

***: As measured TC concentration and / or IC concentration were below the lower limit of quantification, TOC concentration could not be calculated

 

Test substance concentrations in soluble fraction:

Stirring period (day)	Sample	TC		IC		TOC concentration (mgC/L)
		Area	Concentration (mgC/L)	Area	Concentration (mgC/L)
1	1D-1	1.0670	(0.5237)*	7.3950	(0.2199)**	--***
	1D-2	1.7907	(0.8788)*	7.8570	(0.1977)**	--***
	1D-3	2.0047	(0.9838)*	8.1860	(0.2574)**	--***
2	2D-1	2.4533	1.1806	5.7980	(0.1594)**	--***
	2D-2	2.3910	1.1506	7.9597	(0.2188)**	--***
	2D-3	2.0633	(0.9929)*	7.6210	(0.2095)**	--***
3	3D-1	2.9997	1.4026	10.0043	(0.2795)**	--***
	3D-2	2.3723	1.1093	9.6850	(0.2705)**	--***
	3D-3	4.2027	1.9651	9.3897	(0.2623)**	--***

*: Measured TC concentration was below the lower limit of quantification (< 1 mgC/L).

**: Measured IC concentration was below the lower limit of quantification (< 1 mgC/L).

***: As measured TC concentration and / or IC concentration were below the lower limit of quantification, TOC concentration could not be calculated

 

From the above table, since TC and / or IC contained values below the lower limit of quantification, it was not possible to calculate the concentration of TOC (mgC/L) in the soluble fraction by subtracting the IC concentration from the TC concentration. Therefore, in order to confirm the difference between the blank sample and the soluble fraction of each day, the Student's t-test was performed using the area value of TC.

For statistical analysis of data, commercially available statistical processing software Statlight (Yukms Corp., Tokyo) was used. The level of statistical significance was set at 5%. As a result, no significant difference was found between the TC area value of the blank sample and that of the soluble fraction in all days.

 

 

Conclusion

The water solubility test of the test substance was estimated by the flask method. In order to confirm the concentration of the test substance in water, TOC measurement was performed. However, the TOC concentration for the soluble fraction could not be calculated since the TC concentration and/or IC concentration were below the lower limit of quantification (TC: < 1 mgC/L to 1.9651 mgC/L, IC: < 1 mgC/L). Furthermore, there were no significant difference between the TC peak area of blank sample and that of soluble fraction. Therefore, it was considered that water solubility of the test substance is low.

Applicant's summary and conclusion

Conclusions:

The water solubility of the test substance < 1mg/L.