Nitrate determination in natural waters by spectral photometry with a miniaturized fiber-coupled flow cell

摘要

For in situ monitoring of natural waters in respect of impurities miniaturized spectral analytical systems become more and more important. A case in point are nitrate impurities, which can be detected by absorption spectroscopy in the ultra violet (uv) spectral range between 200 and 350 nm. Using uv-transmitting optical fibers, a microoptical flow cell, a miniature polychromator and a deuterium light source, a miniaturized spectral photometer for nitrate detection has been developed. The spectral photometer is a key component in an automatic analyser for in situ measurements in natural waters. To separate the nitrate absorption from the superposition of other uv-absorbing contaminations, for instance nitrite, carbonate and huminic acids, a multi-component analysis (MCA) software has been applied to the detected absorption spectra.. The analyser is suited for the permanent monitoring of nitrate, nitrite and carbonate in inland waters.