Santicizer 2148

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1999-04-13 to 1999-06-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

not specified

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient - HPLC Method)

Deviations:

not specified

GLP compliance:

not specified

Type of method:

HPLC method

Remarks:

HPLC method along with Rekker Calculation method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Key result

Type:

log Pow

Partition coefficient:

> 6.2

Remarks on result:

other: Test carried out at room temperature.

Details on results:

Rekker Calculation Method: for each component, the logarithm of the partition coefficient (n-octanol/water), log Pow was calculated using the Rekker calculation method and the results are presented in Table 1.

HPLC Method: One large peak, one medium peak, and several smaller peaks were observed and retention times are presented in Table 2. It was assumed that the large peak derives from the major component (~80% - Phosphoric acid, C12 alkyl diphenyl ester). Because the calculation method showed that the other four esters in the test material had higher Log Pow values, the small peak at 1.5 minutes probably derived from an impurity rather than from one of the esters. Under the test conditions, the retention time of the reference material 2,4-DDT was 2.6 minutes. Therefore, it was concluded that the parition coefficients of the five organic esters in Santicizer® 2148 Plasticizer were >1.6 x 10^6 (Log Pow >6.2).

Table 1. Rekker Calculation Method: Pow’s and Log Pow’s
Component	Log Pow	Pow
Phosphoric acid, C12 alkyl diphenyl ester (~80%)	7.4	2.5 x 10^7
Phosphoric acid, C14 alkyl diphenyl ester (~10%)	8.3	2.0 x 10^8
Phosphoric acid, C16 alkyl diphenyl ester (~1%)	9.2	1.6 x 10^9
Phosphoric acid, di-C12 alkyl phenyl ester (~7%)	10.9	7.9 x 10^10
Phosphoric acid, C12 alkyl C14 alkyl phenyl ester (~2%)	11.8	6.3 x 10^11

Table 2. HPLC Method: Retention Times
Peak	Retention Time (minutes)
Large Peak	4.9
Medium Peak	7.9
Small Peak 1	1.5
Small Peaks 2 to 7	4.1 to 37.9

Conclusions:

Based on the results of the calculation method and the HPLC method, the parition coefficients (n-octanol/water) of the five organic esters in Santicizer® 2148 Plasticizer were determined to be >1.6 x 10^6 (Log Pow >6.2).

Executive summary:

A key Guideline OECD 117 study was conducted to determine the partition coefficient (n-octanol/water) of the test material Santicizer ® 2148 Plasticizer.

The test material is a mixture of five organic esters prepared from phosphoric acid. For preliminary estimation, Log P_ow values were calculated from the structural formulas of the major components of the test material and the HPLC method was performed to confirm the results of the calculation method.

From the structural formula of each of these components, the logarithm of the partition coefficient (n-octanol/water), log Pow was calculated using the Rekker calculation method(Log Pow = Ʃ ai fi + Ʃ (interaction terms)) where ai = number at which a given fragment is present in the molecule and fi = log pow increment of the fragment.

In the HPLC method, a high performance liquid chromatograph with a spectrometric detector set to read the absorbances at 210 nm was used. The stationary phase was bonded silica C18 while the mobile phase was 95/5 (v/v) acetonitrile/water. A 0.012 g/L reference solution of 2,4-DDT (log Pow = 6.2) and a 1.6 g/L test solution of Santicizer 2148 Plasticizer were prepared in methanol. The solutions were injected in the HPLC system in the following sequence: methanol, the test solution, the reference solution, and methanol. The resultant chromatograms were recorded for 60 minutes. The test was performed at room temperature.

Using the Rekker calculation method, the partion coefficient of the components were determined to be Phosphoric acid, C12 alkyl diphenyl ester (~80% - Log Pow: 7.4, Pow: 2.5 x 10⁷); Phosphoric acid, C14 alkyl diphenyl ester (~10% - Log Pow: 8.3, Pow: 2.0 x 10⁸); Phosphoric acid, C16 alkyl diphenyl ester (~1% - Log Pow: 9.2, Pow: 1.6 x 10⁹); Phosphoric acid, di-C12 alkyl phenyl ester (~7% - Log Pow: 10.9, Pow: 7.9 x 10¹⁰); and Phosphoric acid, C12 alkyl C14 alkyl phenyl ester (~2% - Log Pow: 11.8, Pow: 6.3 x 10¹¹).

In the HPLC method, one large peak, one medium peak, and several smaller peaks were observed and retention times were determined to be: Large Peak (4.9 minutes); Medium Peak (7.9 minutes); Small Peak 1 (1.5 minutes), and Small Peaks 2 to 7 (4.1 to 37.9 minutes). It was assumed that the large peak derives from the major component (~80% - Phosphoric acid, C12 alkyl diphenyl ester). Because the calculation method showed that the other four esters in the test material had higher Log Pow values, the small peak at 1.5 minutes probably derived from an impurity rather than from one of the esters. Under the test conditions, the retention time of the reference material 2,4-DDT was 2.6 minutes.

Based on the results of the calculation method and the HPLC method, the parition coefficients (n-octanol/water) of the five organic esters in Santicizer® 2148 Plasticizer were determined to be >1.6 x 10⁶ (Log P_ow >6.2).

Description of key information

Based on the results of a calculation method and a HPLC method, the parition coefficients (n-octanol/water) of the five organic esters in Santicizer® 2148 Plasticizer were determined to be >1.6 x 10⁶ (Log P_ow >6.2) at room temperature.

Additional information

A key Guideline OECD 117 study was conducted to determine the partition coefficient (n-octanol/water) of the test material Santicizer®2148 Plasticizer (NOTOX B.V., 1999e).

The test material is a mixture of five organic esters prepared from phosphoric acid. For preliminary estimation, Log P_owvalues were calculated from the structural formulas of the major components of the test material and the HPLC method was performed to confirm the results of the calculation method.

From the structural formula of each of these components, the logarithm of the partition coefficient (n-octanol/water), log Pow was calculated using the Rekker calculation method (Log Pow = Ʃ ai fi + Ʃ (interaction terms)) where ai = number at which a given fragment is present in the molecule and fi = log pow increment of the fragment.

In the HPLC method, a high performance liquid chromatograph with a spectrometric detector set to read the absorbances at 210 nm was used. The stationary phase was bonded silica C18 while the mobile phase was 95/5 (v/v) acetonitrile/water. A 0.012 g/L reference solution of 2,4-DDT (log Pow = 6.2) and a 1.6 g/L test solution of Santicizer 2148 Plasticizer were prepared in methanol. The solutions were injected in the HPLC system in the following sequence: methanol, the test solution, the reference solution, and methanol. The resultant chromatograms were recorded for 60 minutes. The test was performed at room temperature.

Using the Rekker calculation method, the partion coefficient of the components were determined to be Phosphoric acid, C12 alkyl diphenyl ester (~80% - Log Pow: 7.4, Pow: 2.5 x 10⁷); Phosphoric acid, C14 alkyl diphenyl ester (~10% - Log Pow: 8.3, Pow: 2.0 x 10⁸); Phosphoric acid, C16 alkyl diphenyl ester (~1% - Log Pow: 9.2, Pow: 1.6 x 10⁹); Phosphoric acid, di-C12 alkyl phenyl ester (~7% - Log Pow: 10.9, Pow: 7.9 x 10¹⁰); and Phosphoric acid, C12 alkyl C14 alkyl phenyl ester (~2% - Log Pow: 11.8, Pow: 6.3 x 10¹¹).

In the HPLC method, one large peak, one medium peak, and several smaller peaks were observed and retention times were determined to be: Large Peak (4.9 minutes); Medium Peak (7.9 minutes); Small Peak 1 (1.5 minutes), and Small Peaks 2 to 7 (4.1 to 37.9 minutes). It was assumed that the large peak derives from the major component (~80% - Phosphoric acid, C12 alkyl diphenyl ester). Because the calculation method showed that the other four esters in the test material had higher Log Pow values, the small peak at 1.5 minutes probably derived from an impurity rather than from one of the esters. Under the test conditions, the retention time of the reference material 2,4-DDT was 2.6 minutes.

Based on the results of the calculation method and the HPLC method, the parition coefficients (n-octanol/water) of the five organic esters in Santicizer® 2148 Plasticizer were determined to be >1.6 x 10⁶ (Log P_ow>6.2).