Hyphenation of Electrochemistry with Mass Spectrometry for Bioanalytical Studies

Abstract

Hyphenation of electrochemistry (EC) and mass spectrometry (MS) is a growing research field with particular importance for bioanalytical applications. It opens the way for studying reaction mechanisms and metabolic pathways of biological compounds and drugs. Electrochemical conversion of sample molecules prior to MS analysis gives rise to short-lived intermediates and products naturally occurring in biological systems, which leads to better understanding of physiological processes. Numerous interesting and attractive studies in this field have been published so far demonstrating potential of EC-MS coupling. The combination with separation system such as liquid chromatography or capillary electrophoresis widens the scope of application providing additional information about compounds of interest. The combination of EC with liquid chromatography has been the most frequently used hyphenated system due to the simplicity of coupling to mass spectrometric detection. In terms of bioanalytical applications capillary electrophoresis offers some advantages and is a complementary technique to liquid chromatography. This review summarizes recent developments in this field from both instrumental and application perspectives. A rather new approach of coupling electrochemistry-capillary electrophoresis-mass spectrometry and its potential for bioanalysis is presented.

Advances in Chemical Bioanalysis

“…This is usually done by using bandpass filters or, alternatively, by attributing the emissions of the components to different color channels of an RGB camera [128,212,228]. A more elegant solution is an application of tailor-made indicators which possess dual emission (oxygen-sensitive phosphorescence and oxygen-insensitive fluorescence) but very few examples have been reported so far [244,254,256,258].…”

“…This is rather surprising since virtually all boron complexes are known to be fluorescent but not phosphorescent (e.g., BODIPY dyes). In dichloromethane solution, BF 2 dbmPLA 91 showed a maximum absorption at 396 nm with a quite high molar absorption coefficient of about 50,000 M À1 cm À1 (Table 5), and an emission maximum at 436 nm with fluorescence quantum yield of 0.89 [256]. In solid state, on the other hand, BF 2 dbmPLA exhibits both delayed fluorescence and long-lived green room temperature phosphorescence, optical properties that can be exploited for single-component oxygen sensors.…”

“…In a more recent report, the same group modified the dually-emissive compound 91 to obtain the iodide-substituted difluoroboron dibezoylmethane-poly(lactic acid) compound 92 [258]. The addition of a heavy atom had the effect of enhancing the spin-orbit coupling and therefore increasing the rate of intersystem crossing, rendering 92 more practical for sensing applications.…”

“…In mixed-culture populations, redox mediators produced by one type of microorganism have been reported to be useful for enabling another microorganism to achieve ET to the electrode [113,249], mutualism of this sort being reported to enhance current generation in MFCs [255]. During the initial years of MFC research, use of exogenous mediators was very common [24,35,256,257]. Although their use has since declined, exogenous mediators are nevertheless still being used to improve MFC performance [258][259][260].…”

“…During the initial years of MFC research, use of exogenous mediators was very common [24,35,256,257]. Although their use has since declined, exogenous mediators are nevertheless still being used to improve MFC performance [258][259][260]. The artificial mediators used most frequently to facilitate Fig.…”