E-mail: wyh gxu. To gain more insight into the mechanism of quinone reduction, we explored the effect of experimental factors that are influential to corona discharge CD. Therefore, a conclusion can be drawn that the reduction of quinones is closely related to CD. Qin et al. However, in-depth evidence was still absent.
An ESI source can be viewed as a controlled-current electrolytic cell, in which oxidation reaction occurs in the positive mode and reduction reaction occurs in the negative mode. By adjusting experimental parameters of spray voltage, solvent composition, sheath gas, spray emitter material, and flow rate of electrospray, it illustrated that the reduction of these quinones in negative ESI MS was closely related with CD in the gas phase.
Knowing the mechanism of quinone reduction is beneficial to efficient qualitative and quantitative analysis of quinonoid compounds in various complex matrixes, such as the analysis of DCBQ in drinking water. Solvent composition affects the extent of discharge in electrospray. With higher flow rate, the intensity of CD-induced luminescence was weaker. Sheath gas affects CD via changing the surrounding circumstance where CD occurs.
The dielectric strengths of O 2 , N 2 , and SF 6 are 0. Spray voltage and spray emitter material can also affect CD during ESI, 14 which was characterized via luminescent intensity in our previous work.
Metal spray emitter discharges more drastically than fused silica spray emitter under the same conditions, because the metal emitter releases electrons more easily than the Taylor cone of the electrospray solution. We suspected that the different reduction behaviours of various quinones might correlate to their reduction potentials, which had been used to explain quinone reduction in FAB 5 and ESI MS.
