ON-SITE ANALYSIS FOR PHOSPHORUS AND NITROGEN IN ENVIRONMENTAL WATER SAMPLES BY FLOW-INJECTION SPECTROPHOTOMETRIC METHOD

On-site analytical methods for the determination of trace amounts of p hosphorus and nitrogen in environmental water samples were investigate d by using flow-injection (FI) technique. Detection reactions used for on-site chemical analysis for ortho-phosphate, nitrite and nitrate we re examined. For economizing the reagents and cutting down waste arose along with chemical analysis to enhance zero emission, a micro-flow i njection (mu FI) technique, in which each flow rate was below one tent h of conventional FI systems and was 50 mu l min(-1), was investigated fundamentally and applied to on-site analysis, and also a micro-react or such as a miniature column for the reduction of nitrate to nitrite was developed. To realize the on-site spectrophotometric measurement, an easy-to-move and a one-box type chemical analyzer was newly develop ed. The analyzer is based on a mu FI technique, works with a battery ( 12V) and can analyze samples rapidly on site with better precision and higher sensitivity than conventional Fl systems. For the sensitive de termination of phosphate, an ion association reaction of molybdophosph ate with Malachite Green was used. Nitrate and nitrite were determined spectrophotometrically on the basis of a diazotization-coupling react ion, where nitrate was reduced to nitrite was found to be useful for o n-site determination of phosphorus as ortho-phosphate at ppb-levels, a nd nitrogen as nitrite and nitrate at ppb-levels in environmental samp les.