Tall oil, maleated

Hydrolysis

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Initiation: September 24, 2013 Completion May 20, 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 111 (Hydrolysis as a Function of pH)

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

no

Analytical monitoring:

yes

Details on sampling:

The test item was extracted from the aqueous samples measured by first acidifying the samples to pH 3.5 with 1N hydrochloric acid, then extracting the aqueous solutions using the C18 SPE cartridges. The cartridges were pre-conditioned using methanol, dichloromethane(DCM)/methanol, methanol, and water acidified to pH 3 – 3.5. Samples (10 mL) were loaded onto the cartridge under vacuum, then washed with 5 mL pH 3 - 3.5 water. The cartridges were then dried under vacuum to remove all traces of water. The test substance was eluted with 5 mL DCM/methanol (95:5).
The extracts were taken to dryness under a nitrogen stream and taken up in 1 mL of HPLC mobile phase. This gave a 10-fold concentration of the test item.

Buffers:

pH 4: 0.05M acetic acid adjusted with NaOH to pH 4
pH 7: 500 mL 0.1M KH2PO4 + 296.3 mL 0.1N NaOH in 1 litre adjusted to pH 7 with HCl or NaOH
pH 9: 500 mL 0.1M H3BO3 in 0.1M KCl + 213 mL 0.1N NaOH in 1 litre adjusted to pH 9 with NaOH

The pH of each solution was checked prior to use. The buffers were sterilized by filtration through an 0.20 μm cassette filter prior to use.

Duration:

5 d

pH:

4

Temp.:

50 °C

Initial conc. measured:

16.7 mg/L

Duration:

5 d

pH:

7

Temp.:

50 °C

Initial conc. measured:

169.9 mg/L

Duration:

5 d

pH:

9

Temp.:

50 °C

Initial conc. measured:

208.8 mg/L

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Statistical methods:

Percent difference between initial (time zero) and final (5 days incubation at 50 °C) was calculated according to the formula:
%Difference = (area count difference)*100/Initial area counts

Preliminary study:

yes
The test solutions were prepared in duplicate and incubated at 50 °C for five days in a modified GC oven.
Incubated test solutions were run on a calibrated HPLC system to determine if any hydrolysis had occurred.

Transformation products:

no

% Recovery:

10.3

pH:

9

Temp.:

50 °C

Duration:

5 d

% Recovery:

-6.1

pH:

7

Temp.:

50 °C

Duration:

5 d

% Recovery:

-6.2

pH:

4

Temp.:

50 °C

Duration:

5 d

Key result

Remarks on result:

hydrolytically stable based on preliminary test

Details on results:

The material is clearly hydrolytically stable at pH 4 and 7. We observed a 10.3% difference at pH 9 however. In order to determine whether this difference was significant, we re-checked all integrations and the error associated with the measurements. The mean relative percent difference between all pairs in the experiment was 8.8% (n = 4). Applying this value to calculate the range associated with the pH 9 time zero and day 5 measurements, we observed that the ranges overlapped (2955 - 3605 counts for the initial value and 3333 - 3983 counts for the final, day 5 result). Given that the ranges overlapped, we conclude that the two values are not significantly different, using non-parametric statistics. We repeated this calculation using the error (actual measured vs expected) associated with our sample spikes in the experiment. The 95% confidence intervals (mean ±3 standard deviations) for the initial and final measurements similarly overlapped, indicating that the difference is not statistically significant. That being the case, we concluded that the time zero and day 5 values at pH 9 fall within 10% of each other, as simple rounding would suggest.
As well, the day 5 values were higher than the initial at pH 9. It seems unlikely that this would occur due to hydrolysis, which does not usually introduce more unsaturation into the molecule. It is more likely that the increased area counts are due to analytical error or oxidation, which can cause samples to darken in colour. The sample vessels were sealed and purged with nitrogen, but it is hard to ensure the complete absence of oxygen.

Validity criteria fulfilled:

yes

Conclusions:

According to OECD 111, a less than 10% drop in peak area indicates the test item is hydrolytically stable at 50 °C over a five day period and Tier 2 is not required.

Executive summary:

The rate of hydrolysis of the test item EnvaMul 600 has been determined according to test method OECD 111.

The measurement of the test item in the extracts was done using High Performance Liquid Chromatography (HPLC), employing a reverse phase column and mobile phase comprised of phosphate buffer (pH 2) and methanol, in order to retain the test item in its neutral form.

A preliminary test was conductedat 50 °C and pH 4.0,7.0 and 9.0 in order to determine the rate of hydrolysis after 5 days.

According to OECD 111, a less than 10% drop in peak area indicates the test item is hydrolytically stable at 50 °C over a five day period and Tier 2 is not required.

Reference 2

Endpoint:

hydrolysis

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Reason / purpose for cross-reference:

data waiving: supporting information

Description of key information

According to OECD 111, a less than 10% drop in peak area indicates the test item is hydrolytically stable at 50 °C over a five day period and Tier 2 is not required.

No hydrolysis was observed.

Key value for chemical safety assessment

at the temperature of:

50 °C

Additional information

Test item is hydrolytically stable at pH 4, 7 and 9 under the test conditions of OECD 111.