Ready-to-use Calibrants for New IFRA Allergen Testing Method

Markus Obkircher, Research & Development, Merck KGaA, Buchs, Switzerland (

Last year, the International Fragrance Association (IFRA) published a new method for the testing of 57 potentially allergenic fragrances in response to calls to do so by the European Scientific Committee on Consumer Safety (SCCS), which also proposed a corresponding amendment to the EC regulation No. 1223/2009. This new analytical method has been developed by the IFRA Analytical Working Group using gas chromatography and mass spectrometry (GC-MS), to detect and to quantify the 57 fragrance substances and their relevant isomers at a concentration higher than 0.002% (20 mg/kg) in ready-to-inject fragrance materials and oils.

Merck developed two ready-to-use certified reference material mixtures suitable for use as calibrants for the new IFRA method. The substances of those two mixes consist of different alcohol and carbonyl components, that were all individually characterized and their contents determined by quantitative nuclear magnetic resonance (qNMR) spectroscopy according to ISO/IEC 17025 accreditation. In the qNMR measurements a value for the mass fractions was obtained and direct traceability to the SI unit was achieved using acknowledged NIST primary reference materials.

Subsequently, the raw materials were gravimetrically dissolved and diluted in methyl tert-butylether as a solvent following the ISO 17034 accreditation workflow. The resulting bulk solutions were collected in ampules and the process controlled through homogeneity testing by GC-MS. The final ampules were further investigated thoroughly to guarantee stability throughout the whole shelf-life of the product at transportation and storage temperatures.

To guarantee a suitable solution for the customers, the mixtures were intensively tested in a series of interlaboratory comparison studies. With these two ready-to-use standard calibration sets, fragrance manufacturers and testing labs are provided with a very reliable, high-quality product suitable for the new IFRA method.


Short Biography of Presenting Author

Markus Obkircher is the head of Merck’s Reference Materials Research & Development division with teams in the US and Switzerland. He is responsible for the in-house development of new analytical standards and certified reference materials. Prior to this position he was R&D Manager in Buchs, Switzerland, with a strong focus on synthesis, characterization and certification of reference materials. He joined Merck / Sigma-Aldrich five years ago after heading the development unit for a custom API manufacturer. Before that he completed his post-doctoral studies at Harvard in Boston and his PhD thesis in Basel, Switzerland.

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