The Application And Study Of Flow Injection Analysis Technology In Environmental Analysis

In this dissertation, rapid and simple methods for the determination of molybdenum, nitrate and nitrite in environmental samples are developed using flow injection analysis (FIA) spectrophotometry.The dissertation is divided into two sections.In the first section, molybdenum(â…¥) reacts with the mixing reagent (potassium thiocyanate, thiourea, cupper sulfate with different concentration and proportion being mixed) in acidic medium, forming a stable orange-red colored complex. Flow injection analysis is used to exploited the reaction for the determination of molybdenum using a spectrophotometer with a measurement wavelength at 460 nm. Using FIA, a sampling frequency of 36h^-1 is achieved with a detection limit of 0.05mg L^-1. The calibration curve is linear over a range of 1 to 20mg L^-1. The relative standard deviation is <3% for the determination of 10mg L^-1 molybdenum (n=11). The proposed method is applied for the determination of molybdenum in industrial wastewater samples with satisfactory results.In the second section, a fully automated procedure based on sequential injection analysis (SIA) methodology for simultaneous determination of nitrate and nitrite in water samples with a single injection sample is described. Nitrite is determined directly using the Griess diazo-coupling reaction and the formed azo dye is measured at 540nm with spectrophotometer. Nitrate is determined after its reduction to nitrite using coppered cadmium column. Nitrite and nitrate can be on-line determined quickly using...