## 3 Results and Discussion  
The HPLC-MS method was used to analyze (Figures S1-S3) standard NSAIDs solutions consisting of naproxen (0.229 mgL\({}^{-1}\)), diclofenac (0.295 mgL\({}^{-1}\)), and ibuprofen (2.041 mgL\({}^{-1}\)). The retention time  
Figure 3: The analytical procedure for the determination of NSAIDs using an AFFINILUTETM MIP-NSAIDs column and FAPA-MS.  
for analytes in HPLC was determined, and using the mass spectrometer, the value of \(m/z\) signals of analytical significance was determined. For each of the compounds, the analytical signal from the proton attachment was selected. For naproxen, \(m/z\) 231 [M+H]\({}^{+}\); for diclofenac, \(m/z\) 296 [M+H]\({}^{+}\); and for ibuprofen, \(m/z\) 207 [M+H]\({}^{+}\) (Figure 4). The signals in the spectrometry mass apparatus were recorded in two modes: total ion chromatogram (TIC) and extracted ion chromatogram (EIC). Next, using five different concentrations of analytes, the range of linearity of intensity signals [M+H]\({}^{+}\) versus the concentration of drugs and the method detection limit (MDL) were determined (Table 2). The MDL is defined as the minimum measured concentration of a substance that can be reported with 99% confidence that the measured concentration is distinguishable from method blank results. The concentration of a substance that can be reported with 99% confidence indicates that the measured concentration is distinguishable from blank samples. The determined MDL values of drugs in solution using direct HPLC-MS analysis are high and significantly exceed the concentrations of drugs present in waters, sewage, and the environment, so it \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Compound**} & \multirow{2}{*}{\
\begin{tabular}{c} **Analytical** \\ **Signal \(m/z\)** \\ **[M+H]\({}^{\star}\)** \\ \end{tabular} } & \multirow{2}{*}{\(\mathbf{R_{t}}\) **[min]**} & \multirow{2}{*}{
\begin{tabular}{c} **Concentration of** \\ **Drugs in Solution** \\ **Concentration** \\ **[M+H]\({}^{\star}\)** \\ \end{tabular} } & \multicolumn{3}{c}{**The Linearity of**} & \multirow{2}{*}{**MDL TIC \({}^{\star}\)**} & \multirow{2}{*}{**MDL EIC \({}^{\star}\)**} \\  & & & & **Drugs in Solution** & & **[m+H]\({}^{\star}\) vs.** \\ \multicolumn{1}{c}{} & & & & **Concentration** & & **[mg-1\({}^{\star}\)]** & **[mg-1\({}^{\star}\)]** \\ \hline Naproxen & 231 & 4.3 & 0.02 ugL\({}^{-1}\)–3.00 mgL\({}^{-1}\) & 0.030–3.000 & 0.229 & 0.024 \\ Diclofenac & 296 & 8.8 & 0.02 ugL\({}^{-1}\)–3.00 mgL\({}^{-1}\) & 0.005–3.000 & 0.295 & 0.003 \\ Ibuprofen & 207 & 9.1 & 0.02 ugL\({}^{-1}\)–3.00 mgL\({}^{-1}\) & 0.250–3.000 & 2.041 & 0.210 \\ \hline \hline \end{tabular}  
* MDL TIC—method detection limit in total ion chromatogram mode; MDL EIC—method detection limit in extracted ion chromatogram mode.  
\end{table} 
Table 2: Analytical parameters for HPLC-MS in the analysis of drug solutions. Figure 4: Extracted ion chromatogram (EIC) HPLC-MS spectra of naproxen, diclofenac, and ibuprofen. is necessary to pre-concentrate the samples before further analysis. The analytes were concentrated using AFFINILUTETM MIP-NSAIDs columns. The samples were prepared according to the previously described analytical procedure; in these experiments, we used solutions in the concentration range from 0.02 ugL\({}^{-1}\) to 3.0 mgL\({}^{-1}\). The HPLC-MS spectra of the eluent were recorded. Table 3 presents the obtained results regarding analytical parameters. The obtained results indicate that it is a well-functioning and useful analytic tool. However, sample preparation consists of many stages that can accumulate various errors. These errors can significantly affect the result, especially in the case of trace analysis. In addition, sample preparation is time- and cost-consuming, which are crucial factors for large-scale analysis. An additional threat to the environment is the amount of waste generated during sample preparation. Particular attention should be paid to the amount of organic solvents used.