Registration Dossier

Administrative data

Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March, 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was performed according to guideline. The test substance was analytically monitored. The test method was validated with respect to precision and accuracy.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
other: Publication: “Structural determination of zinc dithiophosphates in lubricating oils by gas chromatography-mass spectrometry with electron impact and electron-capture negative ion chemical ionization” Journal of Chromatography A. 905 (2001) 207-222.
Deviations:
no
GLP compliance:
yes
Type of method:
flask method

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Substance type: a mixture of coordination compounds in oil consisting of a zinc metal complex bonded to alkyldithiophosphate ligands.

- Stability under test conditions: A preliminary, Tier 1, hydrolysis study was conducted on the substance according to OECD 111, Annex 1, tiered hydrolysis scheme. Results of the study indicated a > 90% recovery of the parent compound (alkyldithiophosphate ligands) which met the guideline criterion for a hydrolytically stable substance.

Results and discussion

Water solubility
Water solubility:
2 764 mg/L
Temp.:
22 °C
pH:
ca. 5
Details on results:
The water solubility of the substance is 2764 mg/L at 22 degrees C based on chromatographic data.

The GC chromatogram of the water solubles (Figure 2B) shows 3 peaks eluting between 8.7 -11.4 min. Each can be attributed to the pentafluorobenzyl derivatives of ZDDP (zinc dialkyldithiophosphate) based on the characteristic fragment corresponding to the pentafluorbenzyl ion at m/z 181 and the fragment corresponding to the pentafluorobenzyl-dithiophosphate ions at m/z 311 resulting from the loss of two alkyl groups .

The data show that lower molecular weight ZDDPs are preferentially soluble in water. ZDDPs where all alkyldithiophosphate ligands contained C3 (isopropyl) groups accounted for the bulk of the composition of the water sample (95 % by area). A smaller amount of ZDDPs containing mixed isopropyl/1,3-dimethyl alkyl dithiophosphates ligands accounted for the remaining 5 % by area of the water sample

The difference in the water solubility results between mixing times of 24 and 48 hours was 1.9 % which meets the guideline criterion for an acceptable difference of ≤ 15% between the two longest mixing periods

Any other information on results incl. tables

Results.The mean water solubilities for mixing times of 4, 24 and 48 hours are shown below :

 

Table 6. Results of Water Solubility Analysis -Mean Water Solubility at Different Shaking Times

Replicate

Shaking time (hours)

Sum of GC Peak Areas

Water Solubility

(mg/L)

Mean Water Solubility (mg/L)

1

4

60905407

2424

2678.

2

4

83652657

2975

3

4

68772546

2636

1

24

72269519

2723

2738

2

24

83198378

2966

3

24

64513606

2524

1

48

83432557

2971

2791

2

48

63333176

2492

3

48

80513458

2910

*Mean Water Solubility (mg/L)

2764

* mean calculated from 24 and 48 hour shaking times

Table 7. Precision and Accuracy of GC-MS Method

Nominal (mg/L)

Sum of GC Peak Areas

Concentration (mg/L)

% of Nominal

2

10027993

1.53

76.5

2

10252652

1.56

78.0

2

9283441

1.43

71.5

Mean

1.51

75.3

SD

 0.07

 3.4

%RSD

4.5

7

46850834

5.97

85.3

7

37027374

4.93

70.4

7

50176390

6.30

90.0

Mean

5.73

81.9

SD

0.72

10.2

%RSD

12.5

 

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): soluble (1000-10000 mg/L)
The water solubility of the substance is 2764 mg/L at 22 degrees C. The solubility of the substance is dependent on the carbon chain length of the alkydithiophosphate ligands.
Executive summary:

The water solubility of the test substance was determined by the shake flask method according to guidelines in OECD 105.

 

Quantitation of the water soluble components in the ZDDP (zinc dialkyldithiophosphate) test material was performed by GC-MS (gas chromatography-mass spectrometry) following derivatization of the water soluble portion to halogenated derivatives with pentafluorobenzyl bromide CASRN 1765-40-8. Identification of the water soluble components was based on a combination of GC retention times and the interpretation of the fragmentation patterns in the mass spectra obtained for each peak eluted from the GC column.

 

Results of the study indicate the water solubility of the test material is 2764 mg/L at 22 degrees. The GC data indicate the water solubility of this substance is dependent on the length of carbon chain of the alkyldithiophosphate ligands. The lower molecular weight zinc dialkyldithiophosphates containing C3 (isopropyl) alkyl groups are preferentially soluble over the higher molecular weight zinc dialkyldithiophoshates containing all C6 (1,3-dimethyl) alkyldithiophosphate ligands.