Chemical analysis of monomers in epoxy resins based on bisphenols F and A

Abstract

Diglycidyl ether of bisphenol A (DGEBA) is the monomer and most important contact allergen in epoxy resin(s) based on bisphenol A (DGEBA-R). Both thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC) methods are available for the analysis of products containing DGEBA-R. With respect to detection and quantification, epoxy resins of the bisphenol F-type, i.e. epoxy resins containing the isomers of diglycidyl ethers of bisphenol F (DGEBF), are not as well investigated as DGEBA-R. The isomers of DGEBF are p,p'-DGEBF, o,p'-DGEBF and o,o'-DGEBF. Both p,p'-DGEBF and o,p'-DGEBF have been shown to be contact allergens in humans, and all 3 isomers are sensitizers in the guinea pig maximization test. We aimed (i). to develop HPLC methods for separation and purification of the individual DGEBF isomers, (ii). to detect and quantify the DGEBF isomers in epoxy resins of the bisphenol F-type and (iii). to evaluate and develop the TLC as a method for the detection of the DGEBF monomers. We found the total content of the DGEBF isomers in the investigated epoxy resins of the bisphenol F-type to vary from 17.0 to 81.7% w/w. Some of them also contained 0.1-2.4% w/w DGEBA. The HPLC method showed a sensitivity that was 2000-20 000x higher than that obtained with the TLC method for the DGEBF monomers. We concluded that the range of the DGEBF isomer content in epoxy resins of the bisphenol F-type is approximately the same as the monomer content in liquid compared to solid DGEBA-R. The relevance of contact allergy to DGEBA-R can remain unrecognized if the suspected product is an epoxy resin of the bisphenol F-type, which is analysed with the TLC method.

Can simultaneous contact allergies to phenyl glycidyl ether and epoxy resins of the bisphenol A/F‐types be explained by contamination of the epoxy resins?

“…There was no obvious relation between the content of PGE in the studied epoxy resins and the total content of epoxy resin monomers in the same epoxy resins according to the results published earlier (12). Theoretically, epoxy resins of the bisphenol F-type based on novolacs have a smaller repetitive unit than epoxy resins based on bisphenol A or F (Fig.…”

“…The latter types of epoxy resin contain the diglycidyl ether of bisphenol F (DGEBF), which has three different isomers. These are p , p ′‐DGEBF, o , p ′‐DGEBF, and o , o ′‐DGEBF (Figs 1 and 2) (11, 12). The epoxy resins of the bisphenol F‐type can be produced from reacting epichlorohydrin either with bisphenol F or with phenolic novolacs (DGEBF‐R and DGEBF(n)‐R, respectively).…”

An attempt to improve diagnostics of contact allergy due to epoxy resin systems. First results of the multicentre study EPOX 2002

“…Our patch test preparation was made from Epicote 862 ® , which, according to a chemical analysis performed at the Department of Dermatology in Malmö, contained 38% of p , p ′‐DGEBF, 36% of o , p ′‐DGEBF, 13% of o , o ′‐DGEBF and approximately 1% of DGEBA. Hence, the composition of the batch we used for patch testing differed slightly from that recently described by Pontén et al (23). Although DGEBA was contained in our DGEBF‐R‐test preparation, it seems unlikely that reactions to the latter were due to DGEBA because its concentration was only about 25 p.p.m., and reported elicitation thresholds are only exceptionally that low (22).…”

Screening occupational contact allergy to bisphenol F epoxy resin

“…An in‐house DGEBF‐R test substance was included in the baseline series in November 1999. The substance was prepared from Epikote ® 862 (Resolution Europe B.V., Hoogvliet Rt, The Netherlands), which, according to the analyses performed in the Department of Occupational and Environmental Dermatology in Malmö, contains 30–38% p , p ′‐DGEBF, 33–36% o , p ′‐DGEBF, 12–13% o , o ′‐DGEBF, and approximately 1–2% DGEBA . The concentration of this in‐house DGEBF‐R test substance was initially 1% (petrolatum; Period I), and in August 2005 it was lowered to 0.25% (pet.…”

“…DGEBF occurs as three different structural isomers: p , p ′‐DGEBF, o , p ′‐DGEBF, and o , o ′‐DGEBF. All isomers are potent sensitizers in animal tests , and are commonly present in epoxy products . There is strong cross‐reactivity between p , p ′‐DGEBF, o , p ′‐DGEBF, and DGEBA , and concomitant patch test reactions to DGEBF resin (DGEBF‐R) and DGEBA resin (DGEBA‐R, CAS no.…”