Spiramycin analysis

In liquid chromatographic analysis of macrolides and lincosamides, most popular is the ultraviolet detector (Table 29.4). Tylosin, tilmicosin, spiramycin, sedecamycin, and josamycin exhibit relatively strong ultraviolet absorption, but erythromycin, lincomycin, pirlimycin, and oleandomycin show extremely weak absorption in the ultraviolet region. Hence, detection at 200-210 nm has been reported for the determination of lincomycin (146). However, a combination of poor sensitivity and interference from coextractives necessitated extensive cleanup and concentration of the extract. Precolumn derivatization of pirlimycin with 9-fluorenylmethyl chloroformate has also been described to impart a chromophore for ultraviolet detection at 264 nm (140). 

Electrochemical detection is better suited to the analysis of erythromycin and lincomycin. This method of detection has been applied for the determination of erythromycin A (139) and lincomycin (154) residues in salmon tissues. Liquid chromatography coupled with mass spectrometry is particularly suitable for confirmatory analysis of the nonvolatile macrolides and lincosamides. Typical applications of this technique are through thermospray mass spectrometry, which has been used to monitor pirlimycin in bovine milk and liver (141,142), and chemical ionization, which has been applied for identification of tilmicosin (151) in bovine muscle, and for identification of spiramycin, tylosin, tilmicosin, erythromycin, and josamycin residues in the same tissue (150). 

Dubois et al. [59] determined the macrolides tylosin, tilmicoson, spiramycin, josamycin, and erythromycin in swine and bovine muscle, kidney and liver tissue, in bovine milk, and in hen eggs, using roxithromycin as IS. The method involves extraction in a Tris buffer, protein precipitation, SPE clean-up on a Oasis HLB cartridge, and LC-MS-MS analysis in SRM mode. All analytes were confirmed by four ions with an ion-ratio reproducibility ranging from 2.4 to 15%. The sample throughput is 50 samples per analyst per day. Draisci et al. [60] developed a confirmatory method for tylosin, tilmicosin, and erythromycin in bovine muscle, liver, and kidney. The quantification limits were 30, 20, and 50 pg/kg in mnscle, 40, 150, and 50 pg/kg in liver, and 40, 150, 80 pg/kg in kidney for tylosin, tilmicoson, and eiythromycin, respectively. Horie et al. [61] reported the multiresidne determination of erythromycin, oleandromycin, litasamycin, josamycin, mirosamycin, spiramycin, tilmicoson, and tylosin in meat and fish. The LOQ was 10 pg/kg in positive-ion LC-ESI-MS in SIM mode. 

Stolker et al. " described an analytical method based on TFC-LC-MS/MS for the direct analysis of 11 veterinary drugs (belonging to seven different classes) in milk. The method was applied to a series of raw milk samples, and the analysis was carried out for albendazole, difloxacin, tetracycline, oxytetracycline, phenylbutazone, salinomycin-Na, spiramycin, and sulfamethazine in milk samples with various fat contents. Even without internal standards, results proved to be linear and quantitative in the concentration range of 50-500 (xg/1, as well as repeatable (RSD<14% sulfamethazine and difloxacin <20%). The limits of detection were between 0.1 and 5.2 xg/l, far below the maximum residue limits for milk set by the EU. While matrix effects, namely, ion suppression or enhancement, were observed for all the analytes, the method proved to be useful for screening purposes because of its detection limits, linearity, and repeatability. A set of blank and fortified raw milk samples was analyzed and no false-positive or falsenegative results were obtained. 

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