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Doi:10.1016/j.chroma.2003.09.066Journal of Chromatography A, 1022 (2004) 125–129 Liquid chromatography with ultraviolet absorbance detection for the analysis of tetracycline residues in honey Pilar Viñas, Nuria Balsalobre, Carmen López-Erroz, Manuel Hernández-Córdoba Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, E-30071 Murcia, Spain Received 12 May 2003; received in revised form 18 July 2003; accepted 23 September 2003 Abstract
The separation of tetracyclines (TCs) using reversed-phase liquid chromatography (LC) is proposed. The use of an amide-based stationary phase prevents the interaction of tetracyclines with the residual silanol groups and thus avoids the appearance of tailed peaks. Detection wasbased on using an UV spectrophotometer and gradient elution with acetonitrile–oxalic acid as mobile phase permitted good separation ofall the peaks. Specificity was demonstrated by the retention characteristics, UV spectra and peak purity index. Linearity, precision, recoveryand sensitivity were satisfactory. The procedure was applied to the analysis of tetracycline residues (tetracycline, oxytetracycline (OTC),chlortetracycline (CTC), doxycycline (DC), minocycline (MINO) and methacycline (MTC)) in honey of different types. Extraction involvedusing a mild acidic solvent containing EDTA to release protein-bound or sugar-bound tetracyclines. For the clean-up step, solid phase extractionusing phenyl cartridges was applied. Detection limits in the honey using the proposed procedure are between 15 and 30 ng g−1, depending onthe tetracycline.
2003 Elsevier B.V. All rights reserved.
Keywords: Food analysis; Honey; Tetracycline; Antibiotics 1. Introduction
these drugs in honey is illegal at any level The Spanishplan for residue control and healthy food (Plan CREHA) of Tetracyclines (TCs) are broad-spectrum antibiotics which 2002 has established maximum limits for the concentration show activity against Gram-positive and Gram-negative bac- of residual substances As regards the group of tetra- teria, including some anaerobes have been widely cyclines, the analytes included are tetracycline, oxytetracy- used for the treatment of infectious diseases and as an ad- cline (OTC) and chlortetracycline (CTC), which have been ditive in animal foodstuffs. In 1990, the Commission of the analyzed in meat, milk, honey and eggs. The detection limit European Union laid down the procedure for establishing obtained using liquid chromatography (LC) is 20 ng g−1 or maximum residue limits (MRLs) of veterinary drugs in 20 ng ml−1 and the maximum acceptable limit has been set foodstuffs of animal origin. However, no MRLs have been at 100 ng g−1 or 100 ng ml−1. These limits are similar to fixed for use with bee products. Antibiotics such as tetracy- those marked by the Belgian Agency for Safe Foods.
clines have had MRLs imposed for their use in large animals Tetracyclines can be successfully determined using liquid but are illegal for use with bees. Honey is composed primar- chromatography (LC) in the reversed-phase mode ily of sugars and water a natural healthy food. At with different detection modes, such as spectrophotometry present, application of the law in relation to these antibiotics is not harmonised across all member states. Some countries do not permit honey to contain drugs above the correspond- In the present study, the separation of tetracycline, oxyte- ing detection limit, while others apply an action level such as tracycline, chlortetracycline, doxycycline (DC), minocycline 50 ng g−1. However, it must be stressed that the presence of (MINO) and methacycline (MTC) was optimized using anUV detector and a stationary phase involving a ligand withamide groups and the endcapping of trimethylsilyl. This ∗ Corresponding author. Tel.: +34-968367406; fax: +34-968364148.
phase also proved satisfactory for the determination of flu- E-mail address: email@example.com (M. Hern´andez-C´ordoba).
oroquinolone antibacterial agents These tetracyclines 0021-9673/$ – see front matter 2003 Elsevier B.V. All rights reserved.
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