An activated carbon substrate surface for laser desorption mass spectrometry

Abstract

A method to obtain laser desorption/ionization mass spectra of organic compounds by depositing sample solutions onto a carbon substrate surface is demonstrated. The substrate consists of a thin layer of activated carbon particles immobilized on an aluminum support. In common with the porous carbon suspension samples used in previous "surface-assisted laser desorption/ionization" (SALDI) work, the mass spectra contain only a few "matrix" background ion peaks, minimizing interference with analyte ion peaks. The presence of glycerol ensured that the ion signals were stable over hundreds of laser shots. In addition, the carbon substrate surface has several advantages over the suspension samples. The use of a very thin layer of carbon significantly improves the sensitivity. Detection limits range from attomoles for crystal violet to femtomoles for bradykinin. Very little sample preparation is required as the analyte solution is simply pipetted onto the substrate surface and glycerol added. When using an alternate sample deposition method, a mass resolution for bradykinin of 1800 is achieved in linear time-of-flight mode. This is close to the resolution limit set by the detector system and above instrument specification for matrix-assisted laser desorption/ionization mass spectra.

A novel laser desorption/ionization method using through hole porous alumina membranes

“…To date a number of ionization techniques that belong to SALDI have been proposed,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, ...…”

“…The techniques in the other category utilize planar solid substrates with fine structures on the uppermost surface layer as the target plate, so that the photon energies of the laser can reach analytes which are spread over and adsorbed onto the surface and achieve desorption and ionization of analytes 20, 23, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80. Desorption Ionization on Silicon (DIOS) is the representative technique in this category 46.…”

Immobilized carbon nanotubes as matrix for MALDI-TOF-MS analysis: Applications to neutral small carbohydrates

“…For this reason, different matrix substances, such as porphyrins [12,13], inorganic material [14 -17], fullerene [18,19], and porous silicon [20], have also been used to eliminate matrix ion interference. Recently, carbon nanotubes as an alternative to conventional organic matrices were utilized successfully for low molecular mass analytes of peptides, organic compounds, and ␤-cyclodextrin [21].…”

“…To overcome this problem, we are seeking an approach to immobilize carbon nanotubes on the target. Adhesive tape has often been used to immobilize inorganic material such as graphite particles and porous silicon [18,20]. Sunner and Han [18] introduced activated carbon as a matrix for desorption/ionization of proteins and peptides.…”

“…Adhesive tape has often been used to immobilize inorganic material such as graphite particles and porous silicon [18,20]. Sunner and Han [18] introduced activated carbon as a matrix for desorption/ionization of proteins and peptides. In their experiment, they attempted to solve the problem of contamination of the ion source by suspended particles.…”