Portable and inexpensive diode laser fiber-optic spectrometer and its application to the determination of ammonia in environmental samples

In order to analyze the aqueous ammonia, we developed a simple and an inexpensive spectrometer, which consisted of a diode laser, an optical fiber with a dipping probe and a photodiode detector. Preliminary results are described here on the performances of the system in terms of the stability of output intensity, sensitivity, and reproducibility. Data on the comparisons of the system with the conventional UV-VIS spectrometer were also given. With the standard indophenol method, the detection limit for the system is 39 mu g/L which affords enough sensitivity for the determination of ammonia down to mu g/L level. The method was applied to the determination of ammonia in environmental samples including rain and snow. The results shown here indicate a potential for developing a new portable spectrometer useful for the on-site monitoring of environmental samples.