Analytical performance characteristics of nanoelectrospray emitters as a function of conductive coating

Abstract

As miniaturization of electrospray continues to become more prevalent in the mass spectrometry arsenal, numerous types of conductive coatings have been developed with miniaturized electrospray emitters. Different conductive coatings have different properties that may lead to differences in analytical performance. This paper investigates and compares the analytical properties of a series of applied conductive coatings for low-flow electrospray ionization developed in this laboratory vs. commercially-available types. Evaporated graphite is thoroughly compared with commercially available polyaniline (PANI) coated emitters and metal coated emitters. Each set of emitters was investigated to determine various performance characteristics, including susceptibility to electrical discharge in both positive and negative ionization modes, as well as emitter reproducibility and generation of a standard curve to determine each emitter coating's limit of detection and limit of quantitation. Furthermore, evaporated graphite and polyaniline coated fused silica capillaries were investigated to determine which coating is more stable over long-term analyses and during electrical discharge.

Polyaniline‐coated nanoelectrospray emitters treated with hydrophobic polymers at the tip

“…In the studies using borosilicate emitters, 300 µg/mL of NPY solution (MeOH/water/HCOOH, 50:50:0.1) was analyzed by nanoESI‐MS (spray voltage = 3.0 kV). To determine the amount of NPY consumed during the analysis, the average flow rate of the borosilicate emitter had to be measured, as discussed previously 35. The tests were done in triplicate to obtain the average flow rate.…”

Nanoelectrospray emitters: Trends and perspective

“…The latter, however, was shown to be passivated, although it still gave stable spray. Another comparative study was done by Smith et al (2006) for the analytical performance of tips coated with Au/Pt and their own graphite-coated and polyaniline-coated emitters. In their investigation they concluded that the choice of emitter depends on the application.…”

CE with MS detection: A rapidly developing hyphenated technique

“…6A). Nevertheless, substantial progress has been made over the last years and less damageable tip‐coatings based on different metals, conductive organic compounds or graphite have been developed and compared with respect to their performance 112, 113. An interesting approach, showing that low‐flow interfaces can also be realized using a sheath flow design, has been presented by the group of Her 114.…”