# Contamination with Pharmaceuticals in Aquatic Environment: Focus on Analytical Methodologies
## 3 Determination of Pharmaceuticals in Environmental Samples
### Sample Preparation Techniques
#### 3.1.1 Solid-Phase Extraction (SPE)
A water sample (acidified, pH 1.5) was added to the vial along with magnetic nanoparticles coated with a layer of ionic liquid (vortex, 5 min). After extraction, the nanoparticles were separated from the solution with the help of a magnet, and the desorption of the target analytes took place using 250 \(\,\mathrm{\mu L}\) of 0.5 M phosphate buffer (ultrasound, 10 min). The achieved extraction yields were in the range of 85-116% [61]. As a basis for magnetic nanoparticles, modified sporopolenin was invented [62]. Sporopolenin is a natural biopolymer isolated from the outer cell wall of Lycopodium clavatum spores. They bound/immobilized magnetite (Fe\({}_{3}\)O\({}_{4}\)) to the surface structure of sporopolenin and subsequently substituted the hydroxyl functional group with silica gel derivatives (3-cyanopropyltriethoxysilane, tetraethylorthosilicate) in order to ensure and increase the extraction yield of pharmaceuticals (ketoprofen, diclofenac, ibuprofen, and drefenamic acid) from surface and wastewater samples. [PERSON] et al. [62] reported that the synthesized sporopolenin sorption material can be used up to seven times in the sorption-desorption cycle without changing the response of the target analytes analyzed by the HPLC-UV method [62]. [PERSON] et al. first described an automated method that allows the direct injection of wastewater samples for the simultaneous determination of six pharmaceuticals using RAM for online sample preparation. A laboratory-made RAM column with bovine serum albumin (RAM-BSA) was prepared for this purpose. In this case, RAM functions as a precolumn responsible for analyte preconcentration and extraction, with a switching valve connecting it to the analytical column. RAM carriers enable the separation of analytes based on a combination of size exclusion and conventional hydrophobic or ion-exchange interactions, allowing small molecules to pass through while restricting the macromolecules from accessing the extraction phase. Compared to traditional SPE sorbents, RAM sorbents offer many advantages, including a long lifespan, high separation efficiency, reduced analyte loss, low organic waste production, and low overall analysis costs. [PERSON] et al. achieved LODs of 0.01-3 \(\upmu\)g/L using this method [47]. An interesting alternative sorbent for SPE sorbents is carbon nanotubes (CNT), formed by single-walled carbon nanotubes or several layers of graphite (multi-walled carbon nanotubes), with a diameter of several nm and several \(\upmu\)m long, rolled into a cylinder shape [63]. They find application in microextractions in the environmental analysis of waters. [PERSON] et al. [64] replaced the rod used for adsorptive microextraction--BA\({}_{\mathrm{\mu}}\)E with a CNT rod covered with multiple layers of carbon material. A CNT rod (15 mm length \(\times\) 2 mm inner diameter \(\times\) 3 mm outer diameter) was inserted into a 25 mL portion of the sample (pH 5.5) and stirred for 3 h (1000 rpm) at room temperature. The extraction was followed by desorption in 100 \(\upmu\)L of methanol (ultrasound, 30 min). LOQ values of 80 ng/L for all monitored pharmaceuticals in this type of microextraction were achieved [64].