A Pipetting Sample Preparation with Water Eluent followed by Water Mobile Phase HPLC-DAD Analysis for Residual Monitoring of Sulfadimidine in Milk
Authors: Furusawa Naoto 
Published: February 2018

<p>While it is certain that various veterinary drugs used for the prevention and treatment of livestock animal diseases contribute to the stable production of animal products in recent years, on the other hand, the overuse or misuse of these drugs is of great concern because it can result in their presence in animal-derived foods for human consumption.To assure the safety of animal-derived foods for the consumer, Codex Aliamentarius sets maximum residue limits (MRLs) for veterinary drugs.  Because determinations for veterinary drugs in the animal-derived foods are therefore an important specific activity to guarantee food safety, the validated analytical method for the determining target drugs are presently required.</p><p>In answer to the present expansion and diversification in the international animal product trade, the development of international harmonized analytical methods (= universal standard methods) to determine veterinary drug residues in animal products is essential to guarantee equitable international trade in these foods and ensure food safety for consumers.  Without regard for industrial nations and developing countries, the optimal harmonized analytical method for residue monitoring in foods must be quick, easy, reliable, inexpensive, and capable of quantifying residues at concentrations less than the target drug’s MRL in animal products and must cause no harm to the environment and analyst.</p><p>Although several methods have been described in the literature for quantifying veterinary drugs in foods, these methods have three crucial drawbacks as follows: 1) the sample preparation operations are complicated and labor intensive, which are time-and cost-consuming, do not permit the determination of large number of samples, and can give low reproducibility; 2) organic solvents are used as extraction solvents, purification eluent, and/or as LC mobile phases without fail -Risk associated with these solvents extend beyond direct implications for the health of humans and wildlife to affect our environment and the ecosystem in which we all reside.  Eliminating the use of organic solvents is an important goal in terms of environmental conservation, human health and the economy; 3)the detections/identifications are based on LC-MS or -MS/MS - The facilities that LC-MS/MS system is available are limited to part of industrial nations because these are hugely expensive, and the methodologies use complex and specific.  These are unavailable in a lot of laboratories for routine analysis, particularly in developing countries. No optimal method that satisfies the aforementioned requirements has yet been identified.</p>As an optimal technique that can be recommended as an international harmonized analytical method for the routine residue monitoring in animal-derived foods, this paper describes a quick, easy, and small-scale sample preparation followed by an isocratic water mobile phase HPLC method for determining sulfadimidine (SDD) in cow’s milk under no-use organic solvent conditions. The SDD selected here is one of the most frequently used veterinary drugs worldwide, and has only the Codex’s MRL (0.0025 μg/mL for SDD in milk) set for several kinds of sulfonamides.Cow’s milk contains a good balance of protein, fat, and carbohydrate, is an indispensable food because it is inexpensive and readily available.