Pyrolytic lignin

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

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

Version / remarks:

April 2004

Deviations:

yes

Remarks:

uncritical deviation: The reference item mix was dissolved in a different solvent than the eluent (metha-nol/water 75/25 % v/v instead of 65/35 % v/v) in the first determination. Deviation had no impact on the retention times.

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

December 2015

Deviations:

yes

Remarks:

as above

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:

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

Study design

Analytical method:

high-performance liquid chromatography

Results and discussion

Partition coefficient

Partition coefficient 1

Type:

log Pow

Partition coefficient:

ca. 1.7 - ca. 3.8

Remarks on result:

other: Peak 1

Partition coefficient 2

Type:

log Pow

Partition coefficient:

ca. 3.8 - ca. 5.5

Remarks on result:

other: Peak 2

Partition coefficient 3

Type:

log Pow

Partition coefficient:

ca. 5.5 - ca. 5.9

Remarks on result:

other: peak 3

Partition coefficient 4

Type:

log Pow

Partition coefficient:

ca. 5.9 - ca. 6.2

Remarks on result:

other: peak 4

Details on results:

The chromatogram of the test item gave a broad signal with several unresolved peaks, which was separated into four sections for evaluation. Since these peaks are very wide, the log k versus log POW calibration function was used to determine the corresponding log POW values of the start and end of the peaks and a log POW range for each peak were determined.
Although area is not necessarily correlated to the absolute concentration, if a UV detector is used, it is assumed that the detected peaks are representative components of the test item.

Discussion
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.
A peak in the blank value of methanol/water is a known artifact originating from dissolved air, which has no influence on the retention times of the test item.
The correlation log k/log POW is good: the coefficient of determination r2 was calculated to be 0.9923. This value was considered as sufficiently high to use the calibration function for the determination of the log POW of the test item.
Although area is not necessarily correlated to the absolute concentration, if a UV detector is used, it is assumed that the detected peaks are representative components of the test item.
Since the peaks are very wide, the log k versus log POW calibration function was used to determine the corresponding log POW values of the start and end of the main peaks for determination of a log POW range for each peak.
No observations were made which might cause doubts concerning the validity of the study outcome.

Any other information on results incl. tables

 Measurement Data

The retention times of the test item are presented in the following table: 

Measurement	Start Peak 1	End * Peak 1	End * Peak 2	End * Peak 3	End Peak 4
	min.	min.	min.	min.	min.
Measurement 1	0.893	5.435	17.132	22.255	27.413
Measurement 2	0.924	5.420	17.127	22.279	27.289
Measurement 3	0.875	5.462	17.152	22.145	26.958
Mean	0.897	5.439	17.137	22.226	27.220
Standard Deviation	0.024	0.021	0.013	0.071	0.235

* The end time of one peak is identical with the start time of the following peak

Peak Areas Test Item

Measurement	Relative Area Peak 1	Relative Area Peak 2	Relative Area Peak 3	Relative Area Peak 4
	%	%	%	%
Measurement 1	79.11	17.53	2.02	1.35
Measurement 2	79.21	17.61	1.95	1.23
Measurement 3	78.81	17.51	2.32	1.36
Mean	79.04	17.55	2.10	1.31
RSD	0.26	0.28	9.32	5.42

 

Calculated Values

The calculated values are presented in the following table:

Peak	Measurement No.	k	log k	log POW
1 (Start)	1	-0.3739	n.c.*	n.c.*
	2	-0.3527	n.c.*	n.c.*
	3	-0.3867	n.c.*	n.c.*
	Mean			n.c.*
	Standard Deviation			n.c.*
1 (End) = 2 (Start)	1	2.8093	0.4486	3.812
	2	2.7989	0.4470	3.807
	3	2.8280	0.4515	3.820
	Mean			3.813
	Standard Deviation			0.007
2 (End) = 3 (Start)	1	11.0072	1.0417	5.543
	2	11.0039	1.0415	5.542
	3	11.0213	1.0422	5.544
	Mean			5.543
	Standard Deviation			0.001
3 (End) = 4 (Start)	1	14.5981	1.1643	5.901
	2	14.6146	1.1648	5.902
	3	14.5210	1.1620	5.894
	Mean			5.899
	Standard Deviation			0.004
4 (End)	1	18.2135	1.2604	6.181
	2	18.1260	1.2583	6.175
	3	17.8946	1.2527	6.159
	Mean			6.172
	Standard Deviation			0.012

*n.c. = not calculable, log P_OW was not able to be calculated from the capacity factor because the factor was negative.

 

log P_OWwas calculated from the capacity factor as follows:

 

log P_OW= (log k + 0.8574) / 0.3426

 

Validity

The validity criteria and results are presented in the following table:

Peak	Parameter	Criterion	Found	Assessment
1 (start)	Range (Max – Min. log POW)	< 0.1	n.c.*	not valid
	Retention time within Range of Reference Items	2.143 - 29.770	0.897	not within range
1 (end) =2 (Start)	Range (Max – Min. log POW)	< 0.1	0.013	valid
	Retention time within Range of Reference Items	2.143 - 29.770	5.439	within range
2 (end) =3 (Start)	Range (Max – Min. log POW)	< 0.1	0.002	valid
	Retention time within Range of Reference Items	2.143 -29.770	17.137	within range
3 (end) =4 (Start)	Range (Max – Min. log POW)	< 0.1	0.008	valid
	Retention time within Range of Reference Items	2.143 - 29.770	22.226	within range
4 (end)	Range (Max – Min. log POW)	< 0.1	0.022	valid
	Retention time within Range of Reference Items	2.143 - 29.770	27.220	within range

* n.c. = not calculable

Applicant's summary and conclusion

Conclusions:

the log POW range of the test item components is <1.7 – 6.2

Executive summary:

The study was performed using a HPLC with a C18 column, according to OECD guideline 117. Seven 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.

The chromatogram of the test item gave four peaks. Since the peaks are very wide, the log k versus logP_OW calibration function is used to determine the corresponding logP_OW values of the start and end of the peaks and a logP_OW range for each peak were determined:

 

Peak	Relative Area	Retention Time start	Retention Time end	Log POW ± Standard Deviation
	[%]	[min]
1	79.04	0.897	5.439	< 1.7* - 3.8±0.01
2	17.55	5.439	17.137	3.8±0.01 – 5.5±0.00
3	2.10	17.137	22.226	5.5±0.00 – 5.9±0.00
4	1.32	22.226	27.220	5.9±0.00 – 6.2±0.01

*Peak start lay within the dead time of the method and not within the range of log P_OW values of the reference items. Therefore, the corresponding log P_OW value should be stated as < 1.7

These values are the means ± standard deviations of three independent determinations.

Although area is not necessarily correlated to the absolute concentration, if a UV detector is used, it is assumed that the detected peaks are representative components of the test item, indicating that the logP_OW range of the test item components is <1.7 – 6.2.