Sometimes, innovation in an approach is as important as innovation in a product. When scientists at Thermo Fisher Scientific faced the challenge of analyzing four types of antibiotics from dried distillers grains with solubles (DDGS), they realized some creative thinking would be needed. Penicillin G, erythromycin, and virginiamycin S₁ and M₁ are the four major antibiotics used in ethanol production. They belong to different antibiotic classes that include β-lactams, macrolides and streptogramins. Extraction and separation of these chemically diverse antibiotics has proved difficult—especially because they lack good chromophores.

DDGS, the dried remains of ethanol production from corn, is a valuable commodity as a feed supplement for livestock and poultry because it is rich in protein, fat, minerals and vitamins. During corn fermentation, a mixture of antibiotics is added to prevent bacterial growth, which reduces ethanol yield. These antibiotics can end up in the DDGS which is fed to animals. The U.S. FDA regulates drugs and ingredients used in feed production and has raised concern about levels of antibiotics in DDGS.

Thermo Fisher created a method to extract and separate these antibiotics using a column designed for fast, high-resolution separations of peptides and biological macromolecules. The Thermo Scientific™ Acclaim™ 300 C18 column, which was used in a volatile mobile phase, has wide pores which allow better chromatography than narrow pore columns typically used for antibiotic separations. In addition to an atypical column choice, the method pairs HPLC separation using the Thermo Scientific™ Dionex™ UltiMate™ 3000 RSLC system with the Thermo Scientific™ Dionex™ Corona™ ultra RS™ Charged Aerosol Detector, a universal detector capable of measuring non-volatile and semi-volatile compounds. Charged aerosol detection requires no chromophores for analyte detection and, with sub-nanogram sensitivity, is ideal for measuring these antibiotics at trace levels.

To learn more about this unique method, download the complete application note Determination of Virginiamycin, Erythromycin, and Penicillin in Dried Distillers
Grains with Solubles at www.thermoscientific.com/foodsafetyinsider.