Determination Of Ractopamine Residues In Pigs By Ultra Performance Liquid Chromatography Tandem Mass Spectrometry

Ractopamine hydrochloride is a xenobiotic that belongs to a large group of ß2-adrenergic agonist compounds. ß2-Agonists are used in human and veterinary medicine for treatment of lung diseases as bronchodilators, tocolytics and heart tonics (Courtheyn et al., 2002; Malucelli et al., 1994; Meyer & Rinke, 1991). Besides their legal use, these drugs are often misused as growth promoters, to improve carcass composition by decreasing fat to the benefit of muscle mass, gaining higher economic benefit to producers (Anderson et al., 2009; Moody et al., 2000). Ractopamine hydrochloride increases the amount of lean meat and decreases the amount of carcass fat when fed to swine during the last 50 kg of gain, also increasing the rate of weight gain and feed conversion (Anderson et al., 1989; Merkel et al., 1987; Watkins et al., 1990; Williams et al., 1994). The biochemical basis of ractopamine effects is increasing the nitrogen retention, protein synthesis, enhancing lipolysis and suppressing lipogenesis (Apple et al., 2007; Armstrong et al., 2004; Carr et al., 2005; Mills, 2002; Mitchell et al., 1990; Mitchell, 2009). Illegal use of ß2-agonists in 5to 10-fold therapeutic doses leads to accumulation of these compounds in animal tissues such as liver, kidney and muscle (Smith, 1998; Smith & Shelver, 2002). High amounts of ß2-agonist residues in meat and meat products led to a number of cases of food poisoning in humans in the last 20 years (Brambilla et al. 1997; Garay et al., 1997; Martinez-Navarro, 1990; Pulce at al., 1991; Ramos et al., 2003), although the Council Directive 96/22/EC banned the use of these substances in the European Union. Consequently, detection of ß2-agonists in biological material from farm animals is a high priority because of the public health concern; relatively large numbers of samples have to be analyzed and more stringent criteria used in view of the serious public health implications of positive results. In order to provide quality assurance for the consumer and to satisfy legal testing obligations, the ability to detect drug residues at low concentrations has become a very important issue. Although all incidents of poisoning were caused by clenbuterol toxicity, the European Union has placed ban upon the use of all ┚-agonists, thus requiring strict monitoring for the illegal use of this and other ┚-agonists. Ractopamine was approved by the U.S. Food and