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Both spectral and time-resolved fluorometry have important potential applications in on-line microbial monitoring for chemical and biological life support systems. Spectral fluorometers operating with remote fiber-optic probes have demonstrated their potential for detecting, identifying and quantifying bacteria and fungi in recirculated plant nutrient solutions. This same spectral fluorometry can play a similar role in detecting and identifying pathogenic bacteria in water supplies. Time-resolved fluorometers, also operating in the on-line fiber-optic mode, have exceptional sensitivity and are capable of detecting extremely low bacterial population densities in both air and water in life support applications. Fluorometric data, both spectral and time-resolved, are characterized by background luminescence and interfering, overlapping spectra from various living and non-living fluorometric sources.

Significant needs exist for on-line real-time monitoring of water quality and hydroponic plant nutrients in regenerative life support systems. Toxic metals and organic pollutants in recirculated water are more effectively controlled by on-line monitoring. Biomass production of various crops may be enhanced by optimal control of plant nutrients. A new on-line fiber optic spectrometer is in development that uses a combination of ultraviolet-visible absorption measurements in combination with liquid atomic emission spectra to assay a wide variety of chemical compounds and ions in solution. Problems created by interfering, overlapping spectra are solved through the use of pattern recognition methods for multicomponent chemical analysis. This analytical instrument has been successfully applied to the analysis of 15-component plant nutrient solutions.