*2.4. Methods Studied for Analysis of Ceftriaxone in Aquatic and Biological Samples*

Ceftriaxone levels have been estimated using a variety of techniques including HPLC, high performance thin layer chromatography, capillary electrophoresis, and spectrophotometry [37,70]. Literature shows a higher proportion of the usage of HPLC in the analysis of ceftriaxone in the aqueous and biological samples [14]. The methods studied for the analysis

of ceftriaxone include high-performance liquid chromatography coupled with mass spectrometry detection (HPLC-MS) [14,71,72], high-performance liquid chromatography with detection by ultraviolet (HPLC-UV) [14,73–76], and high-performance liquid chromatography coupled with sequential mass spectrometry (HPLC-MS/MS) [14,77–81]. The referred methods studied for the analysis of ceftriaxone also include ultra-performance liquid chromatography with detection by ultraviolet (UPLC-UV) [14,82] and ultra-performance liquid chromatography coupled with sequential mass spectrometry (UPLC-MS/MS) [49,83,84]. The linear range, limit of detection, and recovery of these methods are given in Table 2.


**Table 2.** Comparison of chromatographic methods used for determination of ceftriaxone [85].

Absorption spectroscopy methods such as ultraviolet (UV) [14,86–90], infrared spectroscopy [14,88,90–92], spectrofluorimetry [14,93], microbiological methods [14,94,95], and capillary zone electrophoresis [96] have also been used for the analysis of ceftriaxone. When used as an identification technique, UV has limited selectivity because multiple compounds may have the same or similar spectra. As a result, this technique is typically supplemented with additional spectroscopic techniques such as IR for positive analyte confirmation [35].

#### **3. Methods Used for Removal of Antibiotics from Wastewater**

The selection of the method for wastewater treatment depends on the characteristics of the wastewater and features such as costs, feasibility, efficiency, practicability, dependability, impact on the environment, sludge production, difficulty in operation, pretreatment demands, and the formation of potentially dangerous by-products which characterize the relevant method [97]. The potential of various techniques to remove antibiotics from wastewater systems has been investigated. Among those techniques are constructed wetlands, biological treatment, advanced oxidation processes (AOPs), and membrane technology [23].
