# Contamination with Pharmaceuticals in Aquatic Environment: Focus on Analytical Methodologies
## 3 Determination of Pharmaceuticals in Environmental Samples
### Sample Preparation Techniques
#### 3.1.3 Microextraction Techniques  
Microextraction techniques are highly favored in current analytical practice due to miniaturization and the possibility of automation or the use of small volumes of extraction solvents. The advantage of microextraction techniques is also the elimination of the risk of sample contamination in the sample pretreatment process [67]. Liquid microextraction using hollow fiber (HF-LPME) represents a microextraction technique based on extraction in the pores of the hollow fiber walls. The pores are filled with an organic solvent. Due to the porosity, the target analytes of the sample have a large contact area with the extraction agent, making the extraction process efficient. [PERSON] et al. [17] introduced HF-LPME as a purification and preconcentration technique for monitoring selected pharmaceuticals (ketoprofen, diclofenac, ibuprofen, and naproxen) in treated sewage sludge samples. HF-LPME was also applied to the microextraction of other pharmaceuticals, such as benzodiazepepines [68; 69], sulfonamides in water, etc. [68; 70]. Hydrophobic polymer (polyppropylene) hollow fiber represents a carrier with an applied liquid phase (e.g., ammonium carbonate 0.1 M, organic solvents), which is immobilized in the fiber. The fiber used by [PERSON] et al. [17] for HF-LPME was with the following parameters: 25 \(\upmu\)L volume, 10 cm U-shaped, 600 \(\upmu\)m LD., 200 \(\upmu\)m fiber wall thickness, and 0.2 \(\upmu\)m pore size. The fiber was immersed in the sample, resp. to 100 mL of pressurized hot water extract (PHWE), and the HF-LPME microextraction lasted 120 min with constant stirring with a magnetic stirrer. The resulting 10 \(\upmu\)L of fiber extract was analyzed directly by LC-ESI-MS/MS. This preparation of the samples achieved a significant elimination of the effect of suppressing or increasing the resulting signal during electrospray ionization,and the use of organic solvents of a small volume (a few \(\mu\)L of di-n-hexyl ether) was also an advantage [17]. [PERSON] et al. [19] used dispersive liquid-liquid microextraction (DLLME) to isolate pharmaceuticals from water. DLLME is a technique using a three-component extraction system and is based on the dispersion of the solvent in the sample [71]. [PERSON] et al. monitored six pharmaceuticals from the NSAID group (e.g., ketoprofen, naproxen, sulindac, piroxicam, mefenamic acid, and tolfenamic acid) and six antibiotics (tinidazole, cefuroxime-axetil, ciprofloxacin, sulfamethoxazole, sulfafaazine, and chloramphenicol). Surface water samples after collection were filtered (0.45 \(\upmu\)m nylon filter). A 5 mL portion of the sample was used for the extraction, which was subsequently acidified (HCI 0.1 mol/L, pH 4), and a mixture of solvents, such as methanol/acetonitrile (1200 \(\mu\)L, 1:1, \(v/v\)) and dichloromethane, was added as a dispersion solvent (800 \(\mu\)L of dichloromethane, vortex for 60 s, ultrasound for 10 min). The phases were separated by centrifugation (4000 rpm, 10 min). The supernatant was separated with a microsyringe and the residual sediment phase was evaporated with a stream of N\({}_{2}\). The residue was reconstituted with a mixture of acetonitrile/water (1:1, \(v/v\)), while 5 \(\mu\)L of the filtered extract was analyzed by the UPLC-ESI-MS/MS method. The method was applied to real samples of surface water analysis and achieved LODs of 0.006-0.091 ng/mL, thus ranking among the works of authors who achieved significantly low values of LODs [19]. Bar adsorptive microextraction (BA\(\upmu\)E) was proposed for the microextraction of pharmaceuticals from water samples. BA\(\upmu\)E represents a type of extraction technique for the determination of ultra-trace polar and non-polar analytes in water samples. Moreover, the combination of BA\(\upmu\)E and microfluidic desorption provides a \"green chemistry\" technique compared to the traditional extraction methods [67]. BA\(\upmu\)E was applied to the analysis of pharmaceuticals, e.g., ketoprofen, diclofenac, mefenamic acid [58], or sulfonamide antibiotics [68; 24].