MODULAR PROBE FOR TOTAL INTERNAL REFLECTION FLUORESCENCE SPECTROSCOPY

摘要

An instrument for total internal reflection fluorescence analysis having a probe (1) that inexpensively monitors vapors and liquid-phase analytes under field conditions. The instrument is particularly helpful in the evaluation of multiple analytes using the fluorescence of a probe material immobilized in a thin sorbent polymer coating (21), while at the same time capable of monitoring trace quantities of analyte using a fluorescence-read immunological reaction. The instrument includes a diode laser source (11), an optional variable transmission neutral density filter, an optional focusing element, a shaped optical element (which may be as simple as a microscope slide (15) with beveled edges (17)), one or more amplified photodiode detectors (23), one or more wavelength selective optical filters, and one or more lock-in amplifiers (25). The shaped optical element (15) propagates light (13) from the diode laser (11) in a series of internally reflective bounces (19). The probe is optimized when the angle between the normal to the bevel (17) and incidence of the laser beam is (15 to 20 DEG ). The sorbent polymer coating (21) is deposited on the shaped optical element (15) such that the immobilized fluorophore is excited through the evanescent field of the laser beam (13). The fluorescence emitted from the polymer is collected by a photodiode/amplifier package (23). The fluorescence signal is demodulated and further amplified by a lock-in amplifier (25), and the DC signal is measured and transferred by a digital voltmeter (27) to a computer (29) for recording and charting.