Isolation of sulfonamides from whole egg by supercritical fluid extraction

A supercritical fluid extraction (SFE) method is described for the isolation of sulfonamides from chicken eggs. Whole egg is mixed with Hydromatrix and added to an extraction vessel containing neutral alumina. The sample is extracted at 40°C with supercritical CO2 at 10,000 psi (680 bar) and an expanded gas flow rate of 3.0 L/min to a total volume of 120 L. The sulfonamides are trapped in-line on an alumina sorbent bed. The sulfonamides are eluted post-SFE by using the high-performance liquid chromatographic (HPLC) mobile phase solvent system (phosphate buffer and methanol), followed by separation on an HPLC system using a C18 column and ultraviolet detection at 265 nm. Recoveries from fortified liquid whole eggs (six replicates) at the 0.1-ppm level are 99.5% ± 2.2 for sulfamethazine, 87.8% ± 6.0 for sulfadimethoxine, and 97.6% ± 2.5 for sulfaquinoxaline. The detection limit is 0.025 ppm.