Biological Samples

A paper can be found in the literature describing the use of SiO2@Fe3O4 functionalized with [C4MIM][PF6] IL for the microextraction of four β-blockers (propranolol, metoprolol, atenolol and alprenolol) from human plasma [131]. In the study, two types of hydrophobic ILs, ([C4MIM][PF6] and [C8MIM][PF6]), were tested. The results show that [C4MIM][PF6] o ffered an extraction e fficiency of 75 to 91%, while for [C8MIM][PF6] these values were significantly lower (about 40%). This can be explained by the higher hydrophobicity of the long-chain IL, which leads to poor dispersion in the aqueous sample. Moreover, [C8MIM][PF6] cannot be completely recovered by MNP, which can additionally decrease the extraction e fficiency [132]. In the developed sample preparation procedure,

an e ffervescent powder composed of sodium dihydrogen phosphate and sodium bicarbonate was also applied for the enhancement of the interaction between the magnetic sorbent and the analytes. When this protocol was coupled with LC-MS/MS, the developed method for the analysis of β-blockers in human plasma was able to monitor the compounds of interest with LODs from 0.03 to 0.62 ng/mL.
