Available online at www.sciencedirect.com Talanta 73 (2007) 812–819 Comparison of extraction techniques of robenidine from poultry feed samples Joanna Wilga, Agata Kot- Wasik ∗ , Jacek Namie´ snik Department of Analytical Chemistry, Chemical Faculty, Gda´ nsk University of Technology, G. Narutowicza 11/12 Street, 80-952 Gda´ nsk, Poland Received 16 January 2007; received in revised form 17 April 2007; accepted 30 April 2007 Available online 10 May 2007 Abstract In this paper, effectiveness of six different commonly applied extraction techniques for the determination of robenidine in poultry feed has been compared. The sample preparation techniques included shaking, Soxhlet, Soxtec, ultrasonically assisted extraction, microwave – assisted extraction and accelerated solvent extraction. Comparison of these techniques was done with respect to the recovery extraction, temperature and time, reproducibility and solvent consumption. Every single extract was subjected to clean – up using aluminium oxide column (Pasteur pipette filled with 1 g of aluminium oxide), from which robenidine was eluted with 10 ml of methanol. The eluate from the clean-up column was collected in a volumetric flask, and finally it was analysed by HPLC–DAD–MS. In general, all extraction techniques were capable of isolating of robenidine from poultry feed, but the recovery obtained using modern extraction techniques was higher than that obtained using conventional techniques. In particular, accelerated solvent extraction was more superior to other techniques, which highlights the advantages of this sample preparation technique. However, in routine analysis, shaking and ultrasonically assisted extraction is still the preferred method for the solution of robenidine and other coccidiostatics. © 2007 Published by Elsevier B.V. Keywords: Poultry feed; Sample preparation; Robenidine; Extraction techniques 1. Introduction Sample preparation is one of the most important steps in the majority of analytical procedures to determine trace con- stituents in samples with complex matrices. An ideal sample preparation technique should be simple, inexpensive, efficient, selective and compatible with various analytical techniques. It should give as high as possible recovery the supreme samples clean-up, be environmentally friendly and it should use the min- imum amount of solvent. In practise it is difficult to fulfil all theses requirements. Usually the sample preparation is the most labour intensive, and it is very often the slowest and most costly step in the whole analytical procedure, especially if multi step procedures are used [1,2]. Over the last ten years, research on sample preparation has been driven to solve these problems and find which will the ideal sample preparation technique. ∗ Corresponding author. Tel.: +48 58 347 21 10; fax: +48 58 347 26 94. E-mail addresses: jawil@wp.pl (J. Wilga), agata@pg.gda.pl (A.K. Wasik), chemanal@pg.gda.pl (J. Namie´ snik). Due to their state, solid samples cannot be directly analysed. It is necessary to transfer the analytes from the matrix to the liquid phase so that chromatographic techniques can be used to determine the constituents. Lots of factors can be considered in order to select the proper sample preparation technique, for example the amount of sol- vents used and amount of wastes products obtained, the time needed for the extraction, the cost and availability of instruments, the cost of each operation, the quantity of sample required for the extraction, whether the process is automated and the number of steps that have to be done (which can be a source of mistake) [1]. The extraction techniques that are currently available can be devided into two groups: classical and modern ones. Generally, for classical extraction techniques, like shaking flask extraction (SFE), Soxhlet extraction, Soxtec extraction, the extraction effi- ciency depends mainly on the type of solvent applied for the isolation and extraction time [3,4]. In case of modern extrac- tion techniques, such as ultrasonic assisted extraction (UE), microwave assisted extraction (MAE) and accelerated solvent extraction (ASE), the extraction efficiency depends not only on 0039-9140/$ – see front matter © 2007 Published by Elsevier B.V. doi:10.1016/j.talanta.2007.04.046