Date of Award


Document Type

Open Access

Degree Name

Bachelor of Science






The application of an inexpensive diode-laser-based detector for flow injection analysis (FIA), and the on-line determination of sulfide using the "Methylene Blue (MB) Method" is presented. The detector is designed for simultaneous measurements of transmittance and fluorescence. A 670-nm diode laser is the excitation source; photodiodes serve as detector elements. The flow cell is constructed of a piece of square-cross-section quartz capillary tubing. The MB Method employs N, N-dimethyl-p-phenylenediamine (DMPD), iron III, and sodium sulfide reacting to form MB; a triple-line flow-injection manifold is used. Performed previously using conventional UV-Vis instrumentation, optimized conditions included one reagent dissolved in 9 M sulfuric acid, which renders the method impractical for routine analysis. A fluorescence-based detector is more sensitive than an absorbance-based one, hence this on-line reaction can be performed under less corrosive conditions using fluorescence.

Included in

Chemistry Commons



Rights Statement

In Copyright - Educational Use Permitted.