Photobleaching reaction enhances sensitivity
UV fluorescence mass-detection limits. The method involves the use of multiphoton-excited photochemistry to generate highly luminescent visibleThe ability to analyze extremely small sam- emitting products. Mixtures of hydroxple volumes is one of the most sought after yindoles, including serotonin (5hydroxytryptamine), 5-hydroxytryptostrengths of CE, but decreasing volumes phan, and 5-hydroxyindole acetic acid, are place extreme demands on detection capafractionated by CE. As they exit the capilbilities. Jason Shear and co-workers at the lary column, they intersect with a titaniUniversity of Texas at Austin have found a um:sapphire laser beam that is focused at new detection strategy for CE that imthe column outlet. In the the hyproves the sensitivity for indoles by a factor droxyindoles absorb three or four phoof more than 25 over previously reported tons initiating a photobleaching reaction The photoproducts are excited with two additional near-IR photons producing broad emission bands in the visible region with peak maxima at —500 nm These hvnerluminescent derivatives are much more stable atrainst phornHeoradarion than the narent h drn ind le In most studies that involve fluorescence detection, photobleaching is considered an undesirable drawback that limits the detectability of the analyte. Not in this case. Here, the authors use photobleaching to their advantage to enhance sensitivity for biologically relevant chromophores. Detection limits as low as -70 zmol (-42,000 molecules) Multiphoton-excited hyperluminescence detector for are reported. (Anall Biochem. CE. (Adapted wiih permission. Copyright 1991 1998,260,244-50) Academic Press.)
Resolving large biopolymers Routine characterization of large biopolymers may soon become much easier thanks to the development of a new FT-ICR (ion cyclotron resonance) mass spectrometer by Richard D. Smith and co-workers at Pacific Northwest National Laboratory. The system is based on an 11.5-T superconducting magnet, the highest used to date for FT-ICR that still maintains high field homogeneity. At the core of the system are electrostatic lenses that guide ions between the low-pressure stages of an electrospray ionization (ESI) source and the FT-ICR ion trap. When used in conjunction with ESI, electrostatic ion optics offer several advantages for the detection of large bio-
Smaller leads to faster Looking to speed up your analysis ttme? Think small. That's what Gillian M. Greenway and colleagues at the University of Hull and Zeneca Specialties (both in the U.K.) have done with their inductively coupled plasma (ICP) MS. They developed a miniaturized sample pretreatment step that, when used together with a microconcentric nebulizer, reduced the multielement analysistimefrom 5 to 3 min. A microconcentric nebulizer was used to introduce microliter fractions of sample into the ICPMS at flow rates of
