## Antibiotics
### Simultaneous Analysis of Different Antibiotics  
The separation and quantification of different drugs (macrolides and tetracycline antibiotics) in feedstuffs could be simultaneously carried out by CZE-UV, as demonstrated for TIL, TYL, TC, OTC, and DC with LOD values of 0.5-1 mg/kg [91]. The method sensitivity was good considering that OTC and TYL were added in feeds for growth promotion in a range from a few to 50 mg/kg, and that TIL was also often added as an antimicrobial and respiratory diseases agent at a concentration of a few hundreds of mg/kg [92]. The separation was performed in 15 min and, thus, this CE-method could be considered useful for rapid routine analysis.  
In addition, \(\beta\)-lactams, tetracyclines, quinolones, amphenicols, and sulphonamides were simultaneously and rapidly (8 min) separated by CZE-UV in bovine raw milk. The combination of LLE and SPE extraction procedures before CE-analysis allowed LOQ values lower than MRLs to be obtained [93].  
Another example of a simultaneous separation of different antibiotics (fluoroquinolones, tetracyclines, and \(\beta\)-lactams) in milk was proposed by [PERSON] et al. The use of ECL detector allowed trace to be detected, reaching LOD values of cents and thousands of \(\mu\)g/mL [23].  
If carefully optimized, CE methods could be very promising in routine screening as good alternatives to LC-MS methods. For example, [PERSON] et al. set-up a SPE procedure combined with a MEKC-UV method able to selectively and successfully separate sulfonamides (sulfamethazine, sulfarenzine, sulfathiazole, sulfachloropyridazine, sulfamethoxazole, sulfacarbamide, and sulfaguanidine) and amphenicol-type antibiotics (chloramphenicol, thiamphenicol, and florfenicol) in commercial poultry samples (muscle, liver, and skin with fat) [94].  
More recently, the use of FASS combined with a micelle to the solvent stacking (MSS) approach allowed the set-up of a very sensitive CZE-UV method to detect sulfamethoxazole and trimethoprim (an antibacterial agent frequently used in combination with sulfamethoxazole for respiratory and urinary infections) in dairy products, chicken eggs, and honey. MSS consisted of an injection of a micellar solution plug prior to FASS, in order to obtain a focused sample zone with an increase in CE sensitivity [95].  
In 2019, a microchip-CE with an LED-induced fluorescence detector was used as a promising platform to simultaneously analyze antibiotics in food. The chip was tested for chloramphenicol (CAP) and kanamycin (Kana) quantification in milk and fish samples, obtaining rapid analysis (3 min) with LODs of pg/mL. Unlike other microchip-CE methods, which had the disadvantages of complexity and low versatility, this platform used a simple strategy, named stir-bar assisted DNA multi-arm junctions recycling, which exploited the capacity of a gold bar with the DNA probe to capture antibiotics, allowing a multiplexed detection and increasing the method sensitivity without matrix interference [26].  
To analyze fluoroquinolones and sulfonamides in environmental water, [PERSON] et al. set-up an on-line preconcentration procedure with a pressure-assisted electrokinetic injection (PAEKI) [96]. PAEKI resolves FASI limits in the analysis of anionic molecules, which can be depleted when the voltage is applied in reverse mode. PAEKI parameters (pressure and voltage) were optimized, obtaining LOD values of a few \(\mu\)g/L and improving the results obtained with hydrodynamic or electrokinetic injections [96].