On-chip solid-phase extraction pre-concentration/focusing substrates coupled to atmospheric pressure matrix-assisted laser desorption/ionization ion trap mass spectrometry for high sensitivity biomolecule analysis.
Atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) has proven a convenient and rapid method for ion production in the mass spectrometric (MS) analysis of biomolecules. AP-MALDI and electrospray ionization (ESI) sources are easily interchangeable in most mass spectrometers. However, AP-MALDI suffers from less-than-optimal sensitivity due to ion losses during transport from the atmosphere into the vacuum of the mass spectrometer. Here, we study the signal-to-noise ratio (S/N) gains observed when an on-chip dynamic pre-concentration/focusing approach is coupled to AP-MALDI for the MS analysis of neuropeptides and protein digests. It was found that, in comparison with conventional AP-MALDI targets, focusing targets showed (1) a sensitivity enhancement of approximately two orders of magnitude with S/N gains of 200-900 for hydrophobic substrates, and 150-400 for weak cation-exchange (WCX) substrates; (2) improved detection limits as low as 5 fmol/microL for standard peptides; (3) significantly reduced matrix background; and (4) higher inter-day reproducibility. The improved sensitivity allowed successful tandem mass spectrometric (MS/MS) sequencing of dilute solutions of a derivatized tryptic digest of a protein standard, and enabled the first reported AP-MALDI MS detection of neuropeptides from Aedes aegypti mosquito heads.
Navare
Arti
A
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332, USA.
Nouzova
Marcela
M
Noriega
Fernando G
FG
Hernández-Martínez
Salvador
S
Menzel
Christoph
C
Fernández
Facundo M
FM
D001274:Atmospheric Pressure; D001704:Biopolymers / Q000032:analysis*; D008832:Microchemistry / Q000379:methods*; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000379:methods*; D013048:Specimen Handling / Q000379:methods; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
D001704:Biopolymers