dimethyl 1,2-benzenedicarboxylate;reaction mass of: 1,2-dimethylpropylidene dihydroperoxide

Other distribution data

Administrative data

Endpoint:

other distribution data

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This is a non-standard scientific study that does not follow a guideline and is not performed according to GLP but in a laboratory that is certified according to ISO 9001. The study was reported in detail.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

no guideline followed

GLP compliance:

no

Remarks:

laboratory ISO 9001 certified

Type of study:

other: Leaching of residual peroxide from a gelcoat cured with the test substance

Media:

other: from gelcoat to water and sea water

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

442-480-8

EC Name:

-

Cas Number:

182893-11-4

Molecular formula:

Mixture of C5H12O4 and C10H22O6

IUPAC Name:

reaction mass of 1,2-dimethylpropylidene dihydroperoxide and dimethyl 1,2-benzenedicarboxylate

Details on test material:

Methylisopropylketone peroxide (MIPK), batch BOE07059.

Results and discussion

Any other information on results incl. tables

Peroxide stability tests

The developed HPLC method was first applied to check once more the stability of the T3 and T4 peroxides during storage of their solutions at several temperatures. The selected peroxide concentrations were now substantially lower than those used for the pilot tests. Solutions containing 1.2 mg/l MIPK were prepared in ultrapure water and in seawater simulant and were stored during two weeks at 4°C, 22°C or 40°C. Their peroxide contents were analyzed with intervals of several days.

The conclusions drawn from the pilot tests were confirmed. At 4°C, the peroxides remained stable for two weeks. At 40°C, an unacceptably large degradation of the peroxides occurred. Most of the T4 peroxide was destroyed after two weeks storage, the T3 peroxides were even almost completely degraded within only seven days. At 22°C, T4 peroxide remained stable whereas T3 peroxide was nearly halved. The observation that the most severe peroxide loss occurs at the highest test temperature indicates that the loss is caused by chemical degradation of the peroxides and not by their adsorption, since adsorption is normally seen to have the largest impact at the lowest test temperature.

In view of the rapid degradation of the peroxides at 40°C it was decided to perform the leaching tests on the gelcoat at 22°C.

Leaching tests

A gelcoat, deposited on polyester test strips, was contacted at 22°C during 10 days with either ultrapure water or seawater simulant, applying an area-to-volume ratio of 6 dm2/l. The peroxide content of the contact liquids was analyzed with intervals of several days. The results are illustrated in appendices 8 and 9. In none of the samples any peroxide was detected, implying that the peroxide concentration in the contacted liquids remained below the detection limit of 0.5 μg/l (0.5 ppb). To validate the proper functioning of the HPLC system, a control experiment was conducted in which a group of test strips were contacted during 10 days with an MIPK standard solution instead of with ultrapure water or with seawater simulant. MIPK solutions containing 50 μg/l T4 peroxide, 10 μg/l T4 peroxide or 10 μg/l of each T3 isomer were used. Aliquots from these MIPK solutions were analyzed in parallel with the samples from the ultrapure water and seawater simulant contact experiments. The results are illustrated in appendix 9. When compared to the outcome of the stability test, contact with the gelcoat appears to promote peroxide degradation significantly. After 10 days of contact, the T4 peroxide content from the 50 μg/l solution is almost halved (stability test: T4 stable). Only 20% of T3 peroxides and 20 - 50% of the T4 peroxide from the 10 μg/l solution are recovered after 6 days of contact (stability test: T3 halved after 10 days). The chromatograms however show that the 10 ppb additions of T4 peroxide and T3 peroxide still produce well detectable peaks after 6 days of contact. This demonstrates convincingly that these low concentrations would certainly have been detected in the contact liquids from the leaching tests with ultrapure water and seawater simulant, in case any MIPK peroxides had leached from the gelcoat in large enough quantities to build up a concentration of approximately 2 ppb T3 or T4 peroxide in that contact liquid.

Applicant's summary and conclusion

Conclusions:

1. A reversed phase HPLC method for the determination of type 3 and type 4 methylisopropylketone peroxides was successfully developed. The method is highly selective, yields linear calibration lines, offers a good precision and offers low detection (LOD) and quantitation (LOQ) limits.
2. Methylisopropylketone peroxides appear to decompose rapidly at 40°C, but not at 22°C or 4°C.
3. A leaching study was conducted at 22°C. A gelcoat manufactured with use of MIPK peroxide was contacted during 10 days with ultrapure water or with seawater simulant.
No methylisopropylketone peroxides were detected in these contact liquids

Executive summary:

A reversed phase HPLC method for the determination of type 3 and type 4 Methylisopropylketone peroxides was successfully developed. The method features an in-line solid phase extraction step to concentrate the injected peroxides, a gradient reversed phase separation step to separate the peroxides and a post column reaction in which N,N-dimethyl-pphenylene diammonium-dichloride (DMPD) is oxidized by the peroxide to an intensely colored red compound which is detected by light absorption at 554 nm. The method is highly selective, yields linear calibration lines, offers a good precision and offers low detection (LOD) and quantitation (LOQ) limits. Using this method, the leaching of Methylisopropylketone peroxides from a gelcoat manufactured with use of the substance was investigated. The gelcoat was contacted during 10 days with ultrapure water or with seawater simulant at a temperature of 22°C, applying an area-to-volume ratio of 6 dm2/l. A higher test temperature (e.g. 40°C) was not feasible, since the peroxides then decomposed too rapidly. No Methylisopropylketone peroxides were detected in the contact liquids.