title: Determination of the dead time of a stopped-flow fluorometer.
abstract: This investigation was carried out to develop a convenient alternative method for examining the performance and determining the dead time of a stopped-flow fluorometer. We examined the kinetics for the formation of the fluorescent Mg2+-8-hydroxyquinoline chelate in aqueous solutions. The reversible association of the Mg2+ ion with 8-hydroxyquinoline is a second-order process whose on and off rate constants are dependent on pH. We estimated that the Mg2+ ion chelate has a fluorescence quantum yield of 0.02 in aqueous solutions. Using this reaction we measured the dead time of a stopped-flow fluorometer at different pH values. Measurements of the dead time were found to be reproducible and accurate. The Mg2+-8-hydroxyquinoline reaction fulfills the requirements for a convenient test reaction for dead time measurement of stopped-flow fluorometers. Although the usefulness of the reaction is primarily to determine the dead times of stopped-flow instruments operating in the fluorescence mode, the reaction can also be used for testing an instrument operating in the absorbance mode.
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor 48109.
authors.forename: P
authors.initials: P
authors.lastname: Brissette
authors.forename: D P
authors.initials: DP
authors.lastname: Ballou
authors.forename: V
authors.initials: V
authors.lastname: Massey
mesh_terms: D002021:Buffers; D002614:Chelating Agents; D055598:Chemical Phenomena; D002621:Chemistry; D005470:Fluorometry / Q000295:instrumentation*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007700:Kinetics; D008274:Magnesium / Q000097:blood / Q000652:urine; D015125:Oxyquinoline
chemical_list: D002021:Buffers; D002614:Chelating Agents; D007202:Indicators and Reagents; D015125:Oxyquinoline; D008274:Magnesium