Pyridine-2,6-dicarboxylic acid

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

not specified

GLP compliance:

no

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Test material

Test material information

Constituent 1

Reference substance name:

Pyridine-2,6-dicarboxylic acid

EC Number:

207-894-3

EC Name:

Pyridine-2,6-dicarboxylic acid

Cas Number:

499-83-2

Molecular formula:

C7H5NO4

IUPAC Name:

pyridine-2,6-dicarboxylic acid

Test material form:

solid: crystalline

Study design

Analytical method:

high-performance liquid chromatography

Results and discussion

Partition coefficient

Key result

Type:

log Pow

Partition coefficient:

< 0.3

Temp.:

25 °C

pH:

ca. 1.8

Any other information on results incl. tables

Test ItemDipicolinic acid (DPA)

  Measurement Data

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

Table6.2‑a      Retention Times (RT) Test Item

Measurement	RT
	min.
Measurement 1	1.667
Measurement 2	1.667
Measurement 3	1.667
Mean	1.667
Standard deviation	0.000

 

  Calculated Values

The calculated values are presented in the following table:

Table6.2‑b     Capacity Factor, log Capacity Factor, log P_OWTest Item

Measurement	k	log k	log POW
Measurement 1	0.1905	-0.7200	-0.092
Measurement 2	0.1905	-0.7200	-0.092
Measurement 3	0.1905	-0.7200	-0.092
Mean			-0.092
Relative Standard deviation			0.000

 

log P_OWwas calculated from the capacity factor as follows:

 

log P_OW= (log k + 0.6751) / 0.486

Using the correlation log k / log P_OW, the log P_OWof the peak of test itemDipicolinic acid (DPA)was calculated as -0.092 ± 0.000 (mean ± standard deviation). Because the retention time of the test item lay in the dead time of the method, the calculated log P_OWlay outside the calibrated range. The log P_OWof the test itemDipicolinic acid (DPA)is stated as
< 0.3(log P_OWof 2-Butanone as reference item with the lowest log P_OW) therefore.

1.1.1   Validity

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

Table6.3‑a      Validity Criteria and Results

Parameter	Criterion	Found	Assessment
Range (Max – Min. log POW)	< 0.1	0.000	valid
Value within Range of Reference Items	0.30 - 2.70	-0.092	not valid*

*Because the retention time of the test item lay in the dead time of the method, the calculated log P_OWlay outside the calibrated range. The log P_OWof the test item is stated as < 0.3 (log P_OWof 2-Butanone as reference item with the lowest log P_OW) therefore

Applicant's summary and conclusion

Conclusions:

The log POW of the test item Dipicolinic acid (DPA) is stated as <0.3.

Executive summary:

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_OWare correlated.
The test item is ionisable. The ionisation state of the test item was estimated using non GLP software ACD/I-Lab 2.0: At pH 1.8 the test item is estimated to be uncharged > 90%. Therefore the log P_OWof the test item was determined at pH 1.8.

One vial was filled with the reference item mix and one vial with the test item solution. The vials were analysed using the HPLC with the program described below. First one injection from the solvent blank methanol/30 mM phosphate buffer 65/35 (v/v), pH 1.8 was made. Then three injections were measured from the reference item mix, three injections from the test item and again three injections from the reference item mix.

For each reference item, the capacity factor k was calculated from the retention time of thiourea and the retention time of the respective reference item.

A calibration function (log k versus log P_OW, linear fit) was determined using the literature values for P_OWof the reference items and the retention times in the six determinations.

The correlation log k/log P_OWis good: the coefficient of determination r²was calculated with 0.9601. This value was considered as sufficiently high to use the calibration function for the determination of the log P_OWof the test itemDipicolinic acid (DPA).

Using the correlation log k / log P_OW, the log P_OWof the test item peak ofDipicolinic acid (DPA)was calculated as -0.092 ± 0.000 (mean ± standard deviation). Because the retention time of the test item lay in the dead time of the method, the calculated log P_OWlay outside the calibrated range.

The log P_OWof the test itemDipicolinic acid (DPA)is stated as< 0.3
(log P_OWof 2-Butanone as reference item with the lowest log P_OW) therefore.