Use of glyceroltriheptanoate as marker for processed animal by-products: development and validation of an analytical method

Abstract

A recently published European Regulation requires that the artificial marker, glycerol triheptanoate (GTH), be added to processed animal by-product (ABPs) prohibited from entering the food chain. The objective of this new requirement is to allow full traceability and ensure that these materials are disposed of in a proper way. Here, we report the development and single-laboratory validation of an analytical method for the determination of GTH in meat and bone meal plus animal fat. The method comprises three steps: (1) extraction of GTH from the samples with petroleum ether when analysing meat and bone meal or dissolving the sample in n-hexane when analysing fat; (2) clean-up of the extract using commercially available SPE cartridges; (3) determination of GTH by GC/MS or GC with flame ionisation detection (FID). The results of the validation study demonstrated that the relative standard for intermediate precision varied between 2.5 and 8.2%, depending on GTH concentration and the detector utilised. In all cases, the relative recovery rate was above 96%. The limit of quantification was 16 mg kg⁻¹ (GTH/fat content of the sample) with MS as detector and 20 mg kg⁻¹ with FID. Moreover, the method has been successfully applied in a second laboratory, indicating its transferability. Considering the minimum GTH concentration in ABPs of 250 mg kg⁻¹, the method is considered suitable for the intended purpose and can be utilised by EU Member States laboratories for official control and monitoring.

Keywords:

• marker
• animal by-products
• glyceroltriheptanoate
• method validation

Acknowledgements

We acknowledge Roberto Barcarolo and Gisele Gizzi for their very valuable contributions during the initial phase of this project, and to Ivanka Doncheva for assistance in setting up the TLC experiments. We are also grateful to Stephen Woodgate from the European Fat Processors and Renderers Association for his support during all phases of the project.