Recent Presentation

R. C. Leif, D. Jin, J. Piper, L. M. Vallarino, J. Williams, S.Yang Lanthanide Ion Containing Calibration Beads, ISAC poster 67 (2008)

Introduction: The reliability of the measurements of lanthanide luminescence, both by flow cytometry and by digital microscopy, will be enhanced by the availability of lanthanide calibration beads. These beads can also be used to characterize spectrographic instruments including microscopes. Methods: Both 3- and 5-micron beads containing a luminescent europium complex were manufactured and tested with a time delayed luminescence flow cytometer and a time delayed digital microscope. The distribution of the luminescence from the europium complex in the beads was determined on optical sections by confocal microscopy. The emission spectra of the beads under UV excitation were determined using a PARISS® spectrophotometer. Results: The 5-micron beads were, as expected, much brighter than the 3-micron beads; the 5-micron beads were also more resistant to UV induced fading. Emission peaks were found at 592, 616, and 685 nm. The width of the principal peak at half-maximum (616 nm) was 9.9 nm. The luminescence lifetimes in water and in air were respectively 340 and 460 μseconds. The 5-micron beads were quantitatively detected with the time delayed luminescence flow cytometer in samples with a high fluorescence background. Conclusions: The 5-micron beads can be used for spectral calibration of microscopes equipped with a spectrograph and as test beads for time delayed luminescence flow cytometers. The accurate measurement of the CV of the luminescence emission distribution requires improvements in the instrumentation and/or software.