The FluoroMax-3 is a spectrofluorimeter from JY-Horiba that is applicable to multiple fluorescent intensity measurements. The fluorimeter follows a classical configuration with a Xenon arc lamp, excitation and emission monochromators before and after the sample, a photomultiplier tube (PMT) for detection and a reference photodiode. The Xenon lamp supplies a wide range of excitation light but to perform high resolution fluorescence measurements discrete wavelengths of light must be employed. Wavelength selection is achieved by the optical gratings of the monochromoters which diffract incident light, dispersing it into its constituent wavelength components. In addition, adjustable ‘slits’ form the entrance and exits of monochrometers and these components further resolve light wavelengths. On the excitation monchrometer the slits control the bandpass (range) of light that is incident on the sample whereas the slits of the emission monochrometer determine the intensity of the emitted fluorescence recorded by the PMT. Finally, the reference photodiode is employed to correct for variations in the emission intensity of the Xenon lamp that occur at different wavelengths. As such, the FluoroMax-3 is a serious piece of equipment capable of performing high-resolution and sensitive fluorescence measurements. Further, provision for sample temperature control and stirring mean that this fluorimeter can also be used for cell biological applications in addition to basic solution studies.
The spectrofluorimeter interfaces with a PC and is driven by straightforward, dedicated software called DataMax, this program controls data acquisition and post processing/analysis. Various applications within DataMax are launched through an ‘Instrument Control Center’, another easy to use interface. Four basic applications can be launched from the Instruement Control Center, however optional additional applications can be purchased such as modules for lifetime analysis. The Experiment/Post Processing application controls general fluorescence measurements such as acquisition of emission and excitation profiles. This application also allows time courses of fluorescent intensity to be followed. This ‘time course’ feature has proven useful for cell biological-type questions in our lab including observation of changes in emission intensity in isolated organelles preloaded with indicators. The Constant Wavelength Analysis application permits multiple samples to be analyzed at individual wavelengths and tabulates intensities. This module is somewhat similar to a plate reader although much slower, but it still permits multiple, identical measurements to be made to measure, for example, enzyme reactions or a parameter from multiple samples. The Real Time Display application permits individual hardware parameters (slit width etc.) to be altered whilst immediately displaying the consequent change in emission intensity. As such, acquisition parameters can be readily optimized and transferred to the basic Experiment/Post Processing module for final data acquisition. Finally, the Setup module allows default parameters to be established and saved. In all of the individual applications control of the spectrofluorimeter is relatively simple: the interfaces are as you would expect for a modern piece of scientific equipment. The different modules certainly maximize the usefulness of this piece of apparatus.
Certain things really impressed me about this fluorimeter. Calibration methods, such as lamp scans and water Ramen scans, are explained and pre-programmed. These tests are particularly useful if trouble-shooting is required, not that this has been the case. These methods are comprehensively dealt with and explained such that the user really understands what they are doing. Also, after the fluorimeter had been in our lab for several months the company representative who installed the machine contacted us to check that everything was fine. This doesn’t happen for all equipment and the few issues I did have were rapidly resolved. Finally, the overall ease of use this equipment is superb. The fluorimeter has had multiple users and all seem to have been able to perform experiments readily. One practical point is that the fluorimeter itself is a relatively large piece of equipment (~ 32 x 20 x 10 inches) and space provision for the fluorimeter and PC need to be made.
Peter Haggie, Ph.D.
Post-Doctoral Fellow
University of California, San Francisco