Ultrasensitive detection of waste products in water using fluorescence emission cavity-enhanced spectroscopy

Abstract

Clean water is paramount to human health. In this article, we present a technique for detection of trace amounts of human or animal waste products in water using fluorescence emission cavity-enhanced spectroscopy. The detection of femtomolar concentrations of urobilin, a metabolic byproduct of heme metabolism that is excreted in both human and animal waste in water, was achieved through the use of an integrating cavity. This technique could allow for real-time assessment of water quality without the need for expensive laboratory equipment.water contamination | fluorescence spectroscopy | femtomolar detection

Single nanoparticle detection using split-mode microcavity Raman lasers

“…In high Q microcavities (4), stimulated Raman scattering, also called Raman lasing, has been experimentally demonstrated to possess ultra-low thresholds (5-12), due to the greatly increased light density in microcavities (13). Such microcavity Raman lasers hold great potential for sensing applications.…”

The Dawn of Quantum Biophotonics

“…Femtosecond adaptive spectroscopic techniques for coherent anti-Stokes Raman spectroscopy (FAST CARS) was used to detect small amounts of anthrax-type endospores on a nanosecond time scale [3][4][5] and inside a closed envelope [6]. Fluorescence measurements of fecal matter in water achieved increase of sensitivity by three orders of magnitude [7]. Laserinduced breakdown spectroscopy has been developed to perform studies of plant physiology and phenotyping.…”

“…To achieve both of these goals, an integrating cavity was recently used to enhance both the excitation and collection efficiency [7]. Integrating cavities, especially spherical cavities, are commonly used to measure the total radiant flux from a source, as a means to generate uniform illumination, and as pump cavities for lasers.…”

“…The high reflectivity of the cavity walls leads to a very large effective optical path length over which fluorescence excitation occurs; and the result is excitation of the entire volume of any sample placed inside the cavity. The high reflectivity of the cavity walls also means that fluorescence is collected from all directions; the result is the ability to detect a 500 femtomolar concentration of urobilin [7].…”

“…7.20 Integrating cavity setup for ultrasensitive detection of waste products such as urobilin in water. Adapted from [7] to be the standard reference data for pure water absorption [40,41]. Cavity ringdown spectroscopy (CRDS) is a technique developed for highly accurate and sensitive measurements of low absorption coefficients.…”