I am working at the Department of Biophysics, Panjab University, Chandigarh, India as a Senior Research Fellow. I had the opportunity to use the LS55 fluorescence spectrometer from Perkin Elmer. As part of my master’s project, I had to estimate zinc protoporphyrins (ZPP) in blood samples of lithium and zinc treated rats in order to evaluate lithium meta-toxicity in blood and thereby protective potential of zinc under such toxic states. Zinc protoporphyrins are key markers heavy metal toxicity, iron deficiency and various other pathological states. ZPP is the major non-heme porphyrin formed in red cells as a result of metal toxicity or iron deficiency. I tested and evaluated various protocols. I rated them with respect to sensitivity and specificity as well as other aspects such as ease-of-use, hands-on time, the level of complexity of results interpretation and the required skill level of the user. I found the fluorescent method to be the most sensitive, quick and user friendly.
The LS55 is a monochromator-based fluorescence spectrometer which uses a high energy pulsed xenon source for excitation. Xenon minimizes photobleaching of samples and provides a long-lived excitation source. The variable slit and holographic gratings provide flexibility with very low stray radiation. Holographic gratings are also used on both the excitation and emission monochromators to further reduce stray light and improve the system’s performance. The system is also equipped with a reference signal system which provides control over signal dynamics and reduces noise effectively.
The system has FL WinLab™ software which seamlessly combines PerkinElmer's extensive application-specific knowledge and instrument control with the ease-of-use provided by the Windows® operating environment. Specific modes of instrument operation such as Scan, Time Drive, and Ratio Data Collection can be easily accessed from the application menu of the software. Excitation and emission monochromators can be independently or synchronously scanned, while the Prescan mode is ideal for method development and locating excitation and emission maxima. FL WinLab includes a validation protocol that automatically checks the instrument performance to ensure that it is operating within specification.
I found Perkin Elmer's LS55 fluorescence spectrometer easily operable and the fluorescent analyses software was also easy to interpret and user-friendly. This instrument provided us with easy tool for comparative studies of different samples. At the same time, it gave values of fluorescent intensity, anisotropy as well as fluorescent polarization which were very useful in order parameter calculations. The drawback of the fluorescence spectrometer is its cost. Secondly, instrument takes lot of time to establish a connection with the computer. It remains offline and needs to be switched off and on repeatedly to develop connectivity. This is a waste of time. Thirdly, it is not compact enough to fit in a small area; it requires a spacious lab for installation.
Overall, I recommend the Perkin Elmer LS 55 Fluorescence Spectrometer for its technology, sensitivity, muti-application compatibility, and user-friendly software.
Department of Biophysics
Panjab University