## 2 Results and Discussion  
Organic Poly(Butyl Methacrylate-Co-Ethylene Glycol Dimethacrylate) Monolith Capillary Preparation and Characterization  
Although the proposed monolith synthesis was based on classical radicalar procedures [19; 20], the innovation of this work is related to direct coupling of the poly (butyl methacrylate-co-ethylene glycol dimethacrylate monolith capillary (in-tube SPME) to the LC-MS/MS system. The cross-linking monomer (type and crosslink density), the porogenic solvent (type and amount), and the ratio between the functional and the cross-linking monomers substantially influence the polymer surface area, pore volume, pore size, and porosity [17]. Pore size distribution must be adjusted during monolith preparation, so that the monolith fits the desired application [18]. Table 1 illustrates optimization of the conditions of the organic poly(butyl methacrylate-co-ethylene glycol dimethacrylate) monolith capillary synthesis procedure. The porogenic solvent controls the organic monolith porosity [21; 22]. The porogenic solvents 1-propanol and 1,4-butenodiol employed here produced a homogenous pre-polymer solution containing the monomers. A slight increase in the amount of porogenic solvent generated larger pores, which improved monolithic capillary permeability and favored sample percolation through the capillary under the in-tube SPME system low pressure. Alteration in the cross-linking monomer percentage in relation to the functional monomer modified monolith porosity. High cross-linking monomer concentration decreased both pore size and permeability. On the basis of analyte extraction efficiency (Figure 2), the functional and cross-linking monomer percentages were optimized (Table 1). The M3 monolithic capillary (Figure 2) was selected for the in-tube SPME-LC analysis because it gave the highest extraction efficiency and adequate permeability. Figure 3 shows the cross-sectional SEM images of poly(butyl methacrylate-co-ethylene glycol dimethacrylate) monolith capillary at 200\(\times\) and 10,000\(\times\) magnification. The monolith exhibited continuous (greater homogeneity) coating with interconnected macropores, which allowed the sample to be percolated through the capillary at low pressure. The monolith was clearly tightly attached to the capillary inner-wall. The monolith was fixed to the inner capillary surface by covalent bonds, which dismissed the need for frits [22]. As a result of this chemical attachment and its structure, the monolith exhibited mechanical and chemical stability, as well as biocompatibility with biological samples [22; 23]. The proposed monolithic capillary was reused more than one hundred times without observing significant changes in sorption capacity. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Monolith**} & **Monomer/Porogen** & **EGDMA:BMA** & **Porogens** & \multirow{2}{*}{**AIBN**} & \multirow{2}{*}{**Permeability**} \\  & **(\%\(m/m\))** & **(\%\(m/m\))** & & & \\ \hline M1 & 40:60 & 70:30 & 25:65 & 1\% & Poor \\ M2 & 40:60 & 55:45 & 30:60 & 1\% & Poor \\ M3 & 35:65 & 40:60 & 57:43 & 1\% & Good \\ M4 & 35:65 & 50:50 & 57:43 & 1\% & Good \\ M5 & 35:65 & 30:70 & 57:43 & 1\% & Good \\ \hline \hline \multicolumn{5}{l}{\(\text{BUT}=1\),4-butanediol; \(\text{PRO}=1\)-propanol; \(\text{AIBN}=2\),2-azobisobutyInitrile, \(\text{BMA}=\text{butyl}\) methacrylate, \(\text{EGDMA}=\text{ethyl}\)melgelicol dimetacrylate.} \\ \end{tabular}
\end{table} 
Table 1: Optimization of the organic poly(butyl methacrylate-co-ethylene glycol dimethacrylate) monolith capillary synthesis procedure. Figure 4 depicts the monolithic phase FTIR spectra. The bands at 2960.7 and 1454.4 cm\({}^{-1}\) indicated bond between carbon sp\({}^{3}\) and hydrogen atoms. The band at 1728.6 cm\({}^{-1}\) corresponded to carbonyl bond. The bands at 1388.9, 1254, and 1157.1 cm\({}^{-1}\) were ascribed to symmetric and asymmetric ester C-O bond vibrations.