Extraction of the Beta-Agonist Clenbuterol from Urine Using Clenbuterol SupelMIP

Selective sample preparation is now available based on molecularly imprinted polymers. These highly cross-linked polymeric sorbents give signifi cant benefi ts for trace analysis in complex matrices. They provide lower detection limits, signifi cant time and cost savings and enhanced MScompatibility. Introduction Trace analysis of compounds from complex biological samples require often very extensive and time consuming sample preparation procedures due to the insuffi cient selectivity of traditional SPE sorbents. SupelMIP cartridges are specifi cally designed to selectively extract analytes or classes of analytes at trace levels from complex matrices. They contain SPE sorbents based on molecularly imprinted polymers (MIPs). Selectivity is introduced during the preparation of the MIP sorbent by choosing one or more functional monomers which in solution will form complexes with a template molecule that mimic the analyte or a sub-fragment of the analyte1 (Figure 1). Once the polymer is formed the template molecule is removed from the MIP resulting in specifi c cavities or imprints, sterically and chemically complementary to the analyte or group of analytes of interest. The interactions between the analyte and the functional groups in the cavities are based on hydrogen bonding, ionic, Van der Waals or hydrophobic interactions. Due to multiple interaction sites binding is stronger compared to random binding to traditional SPE sorbents. Clenbuterol, a synthetic beta-agonist, is illegally used as a growth promoter both in humans (doping) and in livestock (breeding)2 (Figure 2). Screening programs are executed all over the world to fi nd the banned drug in food and feed samples, due to the potential health risks associated with beta-agonist residues in meat products. A number of food poisoning cases have been reported with consumption of contaminated meat3, the latest case very recently in Shanghai, where over 300 people were hospitalized4. The determination of beta-agonists in biological samples is at trace levels (typically < 0.5 ng/mL) and in complex biological matrices, such as urine, muscle, liver etc. Conventional SPE materials are normally not selective enough. The highly selective Clenbuterol SupelMIP is designed for extraction of the most common beta-agonist, clenbuterol, from complex matrices. Available is also a class selective Beta-agonist SupelMIP, which extracts a broad range of beta-agonists from complex biological samples. Experimental 5 mL bovine urine was extracted on a Clenbuterol SupelMIP column and compared with extraction on three different mixed-phase cartridges (C4, C8 and C18 mixed with a strong cation exchanger) sigma-aldrich.com/supelmip Figure 2. Chemical Structure of Clenbuterol Cl Cl OH H N C(CH3)3 H2N S P E Figure 1. The basic principle of molecular imprinting