## 5 MIP Applications for the Extraction of Antibiotics in Milk
### Tetracyclines
A SPME-HPLC-FLD method was developed for the determination of OTC, TC, DC and CTC in chicken feed, chicken muscle and milk samples. TC (55.6 mg) and AM (71.1 mg) were dissolved in acetone (11.2 mL) and the mixture was stirred for 12 h. TRIM (1.24 mL) and AIBN (12.4 mg) were added and the mixture (1.5 mL) was transferred into glass tube and degassed under nitrogen stream for 5 min. Etched and silylated fibers were immersed and sealed inside the glass tubes and polymerization was carried out inside a nitrogen evaporator at 60 \({}^{\circ}\)C for 6 h. The coated fibers were collected, placed in tubes filled with nitrogen and heated at 60 \({}^{\circ}\)C for 24 h. The coating procedure was repeated until desired average thickness of 19.5 \(\upmu\)m. The template was removed by soaking the developed TC-MIP coated fibers in methanol-acetic acid (90:10, \(v/v\); 5 mL) for 30 min. TC-MIP coated fibers were applied to pretreated spiked milk extracts in toluene, with an extraction time of 30 min and stirring at 750 rpm and the analytes were eluted with methanol-buffer (30:70, \(v/v\)). In comparison with the respective NIP, binding specificity study between OTC, TC, DC, CTC, phenol and propranolol showed MIP selectivity over OTC, TC, DC and CTC. Furthermore, the developed fibers could be reused for more than 100 extraction cycles [77]. The same laboratory developed two MDE-HPLC-UV methods for the determination of OTC, TC, CTC and DC, utilizing DC- molecularly imprinted magnetic microspheres (MIMMs) and CTC-MIMMs respectively. In the first report, AIBN (0.1 g) and nonionic surfactant (5 mL) were mixed by stirring until full dispersion. DC (0.48 g), MAA (0.9 mL), AM (0.36 g) and water (2 mL) were added and the mixture was strongly stirred and purged under nitrogen stream for 30 min. Fe\({}_{3}\)O\({}_{4}\) particles (1 g) were added and the mixture was stirred for 10 min. TRIM (10 mL) and AIBN (0.1 g) were added and the mixture was sonicated until full dispersion. Hydroxyethyl cellulose (0.12 g) dissolved in water (100 mL) was added and the mixture was purged under nitrogen stream for 10 min and polymerization was carried out at 70 \({}^{\circ}\)C under continuous stirring for 12 h. The developed MIMMs were collected and washed with water, acetone, ethanol and water. DC-MIMMs (50 mg) were preconditioned with methanol (3 mL) and water (3 mL) and dispersed in pretreated milk sample (4 g). The MIMMs were collected by means of a magnet and washed with methanol-toluene (1:19, \(v/v\); 2 mL), the analytes were eluted with 0.5% acetic acid in methanol (2 mL), the eluate was evaporated under nitrogen stream at 40 \({}^{\circ}\)C and the dry residue was reconstituted with mobile phase. In comparison with the respective NIP, MIP adsorption capacity for OTC, TC, CTC and DC were higher [78]. The same MIMM preparation and sample preparation protocol were followed for preparation of CTC-MIMMs utilized for the extraction of OTC, TC, CTC and DC. In comparison with the respective NIP, MIP adsorption capacity for CTC was higher, with Q\({}_{\text{max}}\) values of 10,690 and 71,460 \(\upmu\)g/g [79]. All the reported applications are summarized in Table 4.