p-phenylene diisocyanate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

05 Jul 2018 to 12 Sep 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.19 (Estimation of the Adsorption Coefficient (KOC) on Soil and Sewage Sludge Using High Performance Liquid Chromatography (HPLC))

Version / remarks:

EC Guideline C.19. Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC). March 04, 2016.

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))

Version / remarks:

OECD Guideline 121. Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC). January 22, 2001.

Deviations:

not specified

GLP compliance:

yes

Type of method:

HPLC estimation method

Media:

soil

Specific details on test material used for the study:

No further details specified in the study report.

Radiolabelling:

no

Test temperature:

Column temperature: 35°C +/- 1°C

Details on study design: HPLC method:

Buffer Solutions
Phosphate buffer pH 7, 0.1 M: Solution of 0.1 M potassium di-hydrogen-phosphate in water adjusted to pH 7 using 10N sodium hydroxide. Buffer contained 0.0009% (w/v) sodium azide.
Phosphate buffer pH 7.5, 0.01 M: Solution of 0.1 M Phosphate buffer pH 7 which is ten times diluted in water and adjusted to pH 7.5 using 1N sodium hydroxide. Buffer contained 0.00009% (w/v) sodium azide.

Performance of the Study
The principle of the test method is similar to that of the OECD guideline no. 117: "Partition coefficient (n-octanol/water), high performance liquid chromatography (HPLC) method". While passing through the column along with the mobile phase the test item interacts with the stationary phase. As a result of partitioning between mobile and stationary phases, the test item is retarded. The dual composition of a cyanopropyl stationary phase, having polar and non-polar sites allows for interaction of polar and non-polar groups of a molecule in a similar way as is the case for organic matter in soil or sewage sludge matrices. This enables the relationship between the retention time on the column and the Koc on organic matter to be established.
Stock and test solutions will be prepared in acetonitrile since the sponsor has indicated that the test item reacts with methanol. As mobile phase preferably mixtures of methanol and water will be used. In case the reaction of the test item with the mobile phase is too fast for the performance of the study, a mobile phase of acetonitrile/water may be tried.
According to the guidelines, the determination of the Koc for test items that are ionized for at least 10% within pH 5.5 to 7.5 should be performed with both the ionized and non-ionized form. Therefore, the pKa values of the test item were calculated using the Perrin calculation method (pKalc 5.0, module in Pallas 3.0, CompuDrug International San Francisco, CA, USA). Based on the calculations, the HPLC method was performed pH 7.5.

Analytical Method
Analytical Conditions
Instrument: Acquity UPLC system (Waters, Milford, MA, USA)
Detector: Acquity UPLC TUV or PDA detector (Waters)
Column: Acquity UPLC HSS Cyano, 100 mm x 2.1 mm i.d., dp = 1.8 µm (Waters)
Column temperature: 35°C +/- 1°C
Injection volume: 1 µL
Mobile phase: 55/45 (v/v) acetonitrile/buffer pH 7.5
Flow: 0.4 mL/min
UV detection: 210 nm

Preparation of Solutions
Test Solution
Since the test item is reactive with methanol a 2000 mg/L stock solution of the test item was prepared in acetonitrile. The solution was ultrasonicated for 1 minute. The stock solution was 20 fold diluted with acetonitrile. The final concentration of the test item solution was 100 mg/L.
The test item blank solution was acetonitrile.

Sample Injections
Test item solutions were injected in duplicate. Blank solutions were analyzed by single or duplicate injection.

Key result

Remarks on result:

not determinable

Remarks:

The adsorption coefficient of Paraphenylene diisocyanate (PPDI) could not be estimated using the HPLC method because the test item reacts with water from the mobile phase

Details on results (HPLC method):

Koc HPLC Method
The mobile phase was 55/45 (v/v) methanol/phosphate buffer pH 7.5. In the chromatogram several clustered peaks are showed before the major peak. The retention time of the major peak was similar to the single peak that was observed when analysing a test item solution in methanol with a mobile phase of methanol/phosphate buffer pH 8. To exclude that the test item reacts with methanol in the mobile phase, the methanol in the mobile phase was replaced by acetonitrile.
The mobile phase was 55/45 (v/v) acetonitrile/phosphate buffer pH 7.5. The chromatogram showed one fronting peak. This fronting is most probably caused by the reaction of the test item with water in the mobile phase. Since the guidelines do not allow exclusion of water from the mobile phase, the adsorption coefficient cannot be estimated using the HPLC method.

Validity criteria fulfilled:

not specified

Conclusions:

The adsorption coefficient of Paraphenylene diisocyanate (PPDI) could not be estimated using the HPLC method because the test item reacts with water from the mobile phase.

Executive summary:

The objective of this study was to determine the adsorption coefficient of Paraphenylene diisocyanate (PPDI). 

The adsorption coefficient of Paraphenylene diisocyanate (PPDI) could not be estimated using the HPLC method because the test item reacts with water from the mobile phase.

Description of key information

The adsorption coefficient of Paraphenylene diisocyanate (PPDI) could not be estimated using the HPLC method because the test item reacts with water from the mobile phase.