To establish a method for the simultaneous determination of 7 kinds of veterinary drug residues, including ciprofloxacin, enrofloxacin, ofloxacin (3 kinds of fluoroquinolones), chloramphenicol, thiamphenicol, flufenicol (3 kinds of amphenicols) and isometamidium (1 kind of antitrypanosomal drugs) in milk by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).
Milk samples were extracted by the mixture of acetonitrile and 0.5 mmol/L ammonium formate in methanol (1:1, V:V), purified by n-hexane, dried by nitrogen. The 7 kinds of veterinary drug residues in milk samples were detected by UPLC-MS/MS and quantified by matrix matching external standard method.
The linear range of 7 kinds of veterinary drugs in milk was 1.0–200.0 µg/L with good linearity (r2 were all greater than 0.993). The limits of detection were 0.08–0.44 µg/kg, and the limits of quantitation were 0.28–1.46 µg/kg. Milk matrix had an enhanced matrix effect on all 7 kinds of veterinary drugs. The recoveries of 7 kinds of veterinary drugs at low, medium and high concentrations were 47.44%–117.89%, 82.34%–112.84%, 73.15%–117.69%, respectively. The relative standard deviations were 1.46%–8.26%. This method was used to analyze 9 samples of commercially available milk, and no residues of 7 kinds of veterinary drugs were detected in any of them.
This method is highly sensitive and easy to operate, and can meet the rapid and accurate detection requirements of seven kinds of veterinary drugs in milk.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |