A New Liquid Chromatography Method for the Determination of Essential Oils in Animal Feed Additives

A novel liquid chromatographic method for the measurement of essential oils within animal feed additives was developed and applied. The simple and effective extraction protocol described yielded analyte recoveries more than 90% for cinnamaldehyde, eugenol, carvacrol, capsaicin, and dihydrocapsaicin for the feed additives tested. These five analytes were separated with a peak resolution of more than 1 on a C-18 reversed phase column yielding between 500 000–2 000 000 theoretical plates per meter. UV absorption detection at 210 nm provided limits of detection of approximately 1 µg of analyte per gram of solution for all analytes. Limits of quantitation were approximately 4 µg of analyte per gram of solution. Results indicated that while capsaicin and dihydrocapsaicin were present at conserved levels within feed additives tested (0.2 and 0.05%, respectively), the content of cinnamaldehyde, eugenol, and carvacrol varied considerably. The new method will find use within the emerging field of targeted nutrition for increasing gains for ruminants and poultry.