Pyrolytic lignin

Water solubility

Administrative data

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2021

Report date:

2021

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

July 1995

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

January 2014

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

flask method

Test material

Test material information

Constituent 1

Reference substance name:

Low molecular weight organic substances from fast pyrolysis bio-oil

IUPAC Name:

Low molecular weight organic substances from fast pyrolysis bio-oil

Constituent 2

Reference substance name:

Monomers from fast pyrolysis bio-oil

IUPAC Name:

Monomers from fast pyrolysis bio-oil

Constituent 3

Reference substance name:

Dimers from fast pyrolysis bio-oil

IUPAC Name:

Dimers from fast pyrolysis bio-oil

Constituent 4

Reference substance name:

Trimers from fast pyrolysis bio-oil

IUPAC Name:

Trimers from fast pyrolysis bio-oil

Constituent 5

Reference substance name:

Higher oligomers from fast pyrolysis bio-oil

IUPAC Name:

Higher oligomers from fast pyrolysis bio-oil

Constituent 6

Reference substance name:

Water

EC Number:

231-791-2

EC Name:

Water

Cas Number:

7732-18-5

Molecular formula:

H2O

IUPAC Name:

water

Test material form:

liquid: viscous

Remarks:

Brown /black highly vicous liquid

Results and discussion

Water solubility

Water solubility 1

Key result

Water solubility:

8.89 mg/L

Conc. based on:

test mat.

Loading of aqueous phase:

51 mg/L

Incubation duration:

20 d

Temp.:

20 °C

pH:

>= 4 - <= 6

Water solubility 2

Key result

Water solubility:

225 mg/L

Conc. based on:

test mat.

Loading of aqueous phase:

1 003 mg/L

Incubation duration:

20 d

Temp.:

20 °C

pH:

>= 4 - <= 6

Details on results:

A strong dependency of the solubility on the amount of the test item (nominal load) was perceived in the flasks 1 – 6.
As the solubility was dependent on the nominal concentration, no exact value for the solubility of the test item in water can be stated. Dependency of the pH value on the amount of the test item (nominal load) was also perceived in the main test. Therefore, the concentration of the test item in water was stated as 0.85 – 225 mg/L at 20.0 °C

Any other information on results incl. tables

Measurements during Equilibration

Day	Flask	Conc. DOC Mean [mg/L]	Conc. DOC – blank [mg/L]	Conc. test item [mg/L]
1	1A	29.4	28.9	47.5
2	1B	34.9	34.3	56.4
3	1C	38.4	37.8	62.1
3	blank	0.58	-	-
4	1A	42.7	42.1	69.2
5	1B	42.4	41.9	68.8
6	1C	51.8	51.2	84.2
7	1B	47.4	46.8	76.9
8	1C	60.8	60.2	99.0
	1A	50.1	49.5	81.4
9	1B	50.1	49.5	81.4
10	1C	65.2	64.7	106
11	1A	56.7	56.1	92.2
12	1B	56.3	55.7	91.5
13	1C	75.0	74.4	122
	1A	61.8	61.2	101
14	1B	60.6	60.0	98.7
15	1C	81.0	80.4	132
	1A	65.8	65.2	107
16	1B	61.3	60.7	99.8
17	1C	84.9	84.4	139
18	1A	66.8	66.2	109
19	1B	61.5	60.9	100
20	1C	85.9	85.3	140

pH was 5 – 6 (determined with indicator paper) and temperature was 20 °C at all sampling times

 

A minimal amount of DOC was measured in the blank solution after filtration, therefore the measured value of the blank flask was subtracted from the measured values in the flasks 1A – 1C.

Flask 1C showed a darker colour and significantly higher test item concentrations than flasks 1A and 1B, therefore the evaluation of the equilibration phase was based on each flask individually.

No more significant rising tendency was observed in flasks 1A and 1B between days 15 and 19, and as also Flask 1C showed no more significant increase in test item concentration between day 17 and day 20. The small increase was caused by change of the nominal load in the bottle due to repeated samplings. Therefore, the plateau was considered as reached and the final sampling was performed on day 20.

Measurements at Plateau

Flask	Temperature [°C]	pH*	Concentration DOC Mean [mg/L]	Conc. DOC – blank [mg/L]	Conc. test item [mg/L]
2	20.0	6.03	1.09	0.51	0.85
3	20.0	5.24	5.98	5.40	8.89
4	20.0	5.07	9.19	8.61	142
5	20.0	4.30	88.22	87.6	144
6	20.0	4.09	137.21	137	225

The measured value in the blank flask 0.58 mg/L was subtracted from the measured value in the flasks 2 – 6.

Results

The measurements on day 20 (flasks 1A, 1B and 3 – 6) were included in the calculation of the solubility of the test item in water. Flask 1C was excluded from calculations because the test item concentration was significantly higher in Flask C throughout the equilibration phase.

Flask #	Conc. test item [mg/L]	Nominal Conc. Test Item [mg/L]	Dissolved Part [%]
2	0.85	11	8.0
3	8.89	51	17.3
4	142	103	13.8
1*	144	502	20.8
5	225	750	19.2
6	0.85	1003	22.4

*mean value of flasks 1Aand 1B

 

Conclusion

As solubility was dependent on nominal concentration, no exact value for the solubility of the test item in water can be stated. The solubility range for the tested nominal concentration 11–1003g/L is 8.89–225 mg/L at 20.0 ± 0.5 °C (8.89–225 * 10-3kg/m3in SI units), corresponding to 8.0–22.4 % of the test item relating to the nominal concentration of the test item (Mean value 16.9 % with standard deviation 5.3 %).

 

Applicant's summary and conclusion

Conclusions:

The water solubility was found to be dependent on the nominal concentration. Therefore, the solubility range for the tested nominal concentration 11 – 1003 mg/L is 0.85 – 225 mg/L at 20.0 ± 0.5 °C, corresponding to 8.0 – 22.4 % of the test item relating to the nominal concentration of the test item (Mean value 16.9 % with standard deviation 5.3 %).

Executive summary:

The solubility of the test item in water was determined, according to OECD 105, by

measurement of DOC concentration in the filtrated test solutions using TOC analyser.

During pre-tests for development of a specific analytical method several marker component candidates were tested for quantification of this UVCB substance via LC/MS/MS analysis. As the water solubility of components in UVCB substances can differ substantially, it was considered inadequate to base the water solubility of the mixture on a number of specific components because no information on the solubility of the remaining components is possible.

Therefore, the determination of total organic carbon was favored, because the solubility of the sum of all components is recorded and thus more meaningful information is generated.

As the test item is a UVCB substance, six different loading rates of the test item were chosen to study the effect of the loading rate on the measured water solubility: 10, 50, 100, 500, 750 and 1000 mg/L. Three flasks (1A – 1C) with the same loading rate (500 mg/L) were used during equilibration. Seven vessels (flasks blank, 1C (for the sampling point 72 h) and 2 – 6) were set onto the shaking apparatus immediately and shaking at 150 rpm was started. After 24 ± 2 hours, flask 1B (for the sampling point 48 h) and after 48 ± 2 hours, flask 1A (for the sampling point 24 h) were set on the shaker and all flasks were shaken for further 24 ± 2 hours at room temperature. Then, flasks 1A – 1C were removed from the shaker, tempered at 20.0 ± 0.5 °C, samples were taken, membrane filtered and analysed for DOC via TOC analyser. Due to an upward tendency of the test item concentration, the test was prolonged and the flasks 1A – 1C were sampled and analysed until day 20. As flask 1C showed a much darker color throughout the test than flask 1A and 1B, 1C was not included in the evaluation of the plateau. The final measurement was performed as determination from flasks 2 – 6 on day 20.

DOC was measured via TOC analyser in the saturated aqueous solutions. The pH value in the flasks 2 – 6 lay in the range of 4.09 – 6.03.

No Tyndall effect (i.e. a laser beam was not scattered when transmitted through the liquid) could be observed indicating that no colloidal dispersed particles were present.

A strong dependency of the solubility on the amount of the test item (nominal load) was perceived in the flasks 1 – 6.

As the solubility was dependent on the nominal concentration, no exact value for the solubility of the test item in water can be stated. Dependency of the pH value on the amount of the test item (nominal load) was perceived in the main test.

 

Therefore, the concentration of the test item in water was stated as

 

0.85 – 225 mg/L at 20.0 ± 0.5 °C

0.85 – 225 * 10^-3kg/m³(SI units)

 

for the following nominal concentration range of the test item in water: 10 – 1000 mg/L, corresponding to a dissolved part of 16.9 ± 5.3 % of the test item (mean value ± standard deviation) relating to the nominal concentration of the test item.