Extraction of incurred sulphamethazine in swine tissue by microwave assisted extraction and quantification without clean up by high performance liquid chromatography following derivatization with dimethylaminobenzaldehyde

A rapid and reliable method using microwave energy is described for the extraction of spiked and incurred (freeze-dried and fresh) sulphamethazine residues from swine tissues/organs (muscle, liver and kidney). Incurred tissues were obtained from an abattoir and freeze-dried pig tissue reference materials were produced as part of a reference material study for the Community Bureau of References, European Communities. The extraction was achieved by irradiating the sample in methanol for 25 s in a household microwave oven, commonly referred to as microwave-assisted extraction (MAE). The extracts were analysed without clean-up by high performance liquid chromatography (HPLC) using a C-18 column and detected at 450nm after derivatization with 4-dimethylaminobenzaldehyde (DMABA) in a heated rector at 40 degrees C. The limit of quantitation was 2.5 mu g kg(-1) of wet tissues. A comparison of MAE with an homogenization technique indicated that MAE worked extremely well for freeze-dried samples, while it showed significant variation for wet tissues. No sulphamethazine was detected in retail pork meat and liver samples when analysed by the MAE technique.