Figure 1Chemical structures of ionophore coccidiostats.In selleckchem Olaparib conclusion, to ensure safe and effective use of ionophores, the proper concentrations, precisely as stated in authorization documents, have to be applied. Therefore, the availability of analytical methodology for robust and reliable quantification of ionophores in animal feeding stuffs is essential for both official control and manufacturers’ quality control laboratories.A number of methods for the determination of ionophores in animal feed have been described. Because of the lack of chromophoric groups in their molecules, the derivatisation step is required when spectrophotometric detection is applied [2, 3]. Most of the available methods use postcolumn derivatisation with vanillin [4] or dimethylaminobenzaldehyde, DMAB [5]; such methods are sensitive and robust and require little sample preparation.
Lately, also the mass spectrometric detection has been applied in the determination of coccidiostats in feed [6]. Although MS-based methods can be both used for the reliable determination of single representative of ionophore family [7, 8] and to screen all authorized polyether antibiotics [9], this approach is not always available to routine laboratories because of high cost of purchase and maintenance of mass spectrometer. Also relatively high variation of results is observed due to lack of labelled internal standards.Some of the methods developed so far, using both postcolumn derivatisation/spectrophotometric detection and mass spectrometric approach, have been validated by interlaboratory comparisons and harmonized as international norms [10�C13].
Most of the routine laboratories performing analyses of feed stuffs for ionophore antibiotics follow these official documents. Nevertheless, none of the up-to-date methods enables the determination of all ionophores in single analytical run.The multianalyte protocols are more practical for the organization of laboratory work in terms of quality assurance and sample throughput. Therefore, we have decided to develop single protocol for the determination of all authorized ionophore coccidiostats based on the postcolumn derivatisation methodology, already successfully applied in the determination of monensin, narasin, and salinomycin [11].2. Material and Methods2.1. Chemicals and MaterialsMaduramicin ammonium (MAD), monensin sodium (MON), narasin from Streptomyces auriofaciens (NAR), and salinomycin sodium (SAL) were purchased from Sigma (Germany). Lasalocid A sodium (LAS) was obtained from Dr. Ehrenstorfer. Monensin methyl ester (MON-ME) and semduramicin sodium (SMD) were donated by EU-RL in Berlin. Methanol, HPLC grade, Dacomitinib was purchased from JT Baker (Germany). Methanol p.a.