title: Use of an internal control for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of bacteria.
abstract: A method to aid in the analysis of bacterial samples of unknown concentration by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is demonstrated. It is shown that in MALDI analysis of bacteria, the intensities of resulting peaks in spectra are sensitive to the microbial concentration. At the high and low ends of the concentration range, no signal can be obtained, leaving very concentrated or very dilute samples indistinguishable. The addition of cytochrome c as an internal control allows the differentiation of these concentrated and dilute samples. The presence of the internal control causes only a 20% to 30% decrease in signal intensity when the bacterial concentration is optimum. However, the signal quality is improved when the internal control is added to some low concentrations of bacteria.
authors.affiliation: Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Gantt
authors.forename: N B
authors.initials: NB
authors.lastname: Valentine
authors.forename: A J
authors.initials: AJ
authors.lastname: Saenz
authors.forename: M T
authors.initials: MT
authors.lastname: Kingsley
authors.forename: K L
authors.initials: KL
authors.lastname: Wahl
mesh_terms: D001419:Bacteria / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry; D003574:Cytochrome c Group / Q000737:chemistry; D004926:Escherichia coli / Q000737:chemistry; D012015:Reference Standards; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D016959:Xanthomonas campestris / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D003574:Cytochrome c Group