Study On The New Methods Of Flow Injection Catalytic Spectrophotometry Analysis

Catalytic spectrophotometric method , as a branch of kinetic methods in analytic chemistry, is a useful technique in the determination of trace and ultratrace substances. It enjoys great generality in most laboratory for its high sensitivity, inexpensive instruments and simple operation. When it came into eight decades, analysts combined the technique of flow injecton with catalytic method, which compensated many drawbacks when traditional catalytic spectrophotometric is adopted such as low analysis speed, high regeant cost and inconvenient control of analysis condition, and which greatly promoted the development of catalytic spectrophotometric method.There are two parts in this thesis.Part one: review? The new development of traditional catalytic spectrophotometric method during last six years, among which new approaches, new system, performance enhancement and so on are exploited.? The new development of flow-injection catalytic spectrophotometric method.? Simple introduction of approaches for on-line solution treatment and calibration in flow injection catalytic spectrophotometric methods for simultaneous determination.? Prospect of catalytic method and other techniques for spectrophotometry is presented.Part two: study reportsIn this part, four new catalytic spectrophotometric methods have been established by flow injection technique.First, a new FI catalytic spectrophotometric method using theindication reation between bromate and crystal violet is proposed for the determination of ultratrace amount of nitrite. In dilute phosphoric acid medium, in the presence of propanetriol(propanetriol can enhance sensitivity and deform in the reaction coil) and reaction temperature at 70 癈 , the linear range is 0.05-5ng/mL and the detection limit is 0.02ng/mL. The relative standard deviation of 11 replicate determinations is less than 2%. 72 samples can be analysed per hour. Combining with the separation techinique of ionic exchange, the method has been applied to the determination of trace amount of nitrite in the sample of medicine, vegetable and rain water. The comparison and recovery tests have also been carried out, and satisfactory results is obtained.Secondly, on the basis of the first method, a FI catalytic spectrophotometric method for simultaneous determination of nitrate and nitrite is proposed, in which nitrate is reduced on-line to nitrite by a cadium-coated zinc colume and two sampling loops are kept apart by reducing colume. A peak with a shoulder on the ascending part of the analytical signal is produced. The height of the shoulder corresponds to the nitrite concentration and the maximum of the peak correlates with the sum of both nitrite and nitrate. The linear range is l-50ng/mL for nitrite and 3-150ng/mL for nitrate. Detection limit is 0.3ng/m L and 1.0 ng/m L, respectively. The relative standard deviation of 11 replicate determinations of nitrate or nitrite is all less than 2%. 32-33 samples can be analysed per hour. Combining with the separation techinique of ionic exchange, the method has been applied to the determination of both the ions in various waters. The comparison and recovery tests have also been carried out, and satisfactory results was obtained.Thirdly, a new FI catalytic spectrophotometric method is proposed for the determination of trace amount of formaldehyde. In dilute phosphoric acid medium and reaction temperature at 70 癈, stop flow 180s, the linear range is 0.018-1.4 M g/mL and detection limit is 0.007 u g/mL. The relative standard deviation of 11 replicate determinations is less than 2.5%. 15 samples can be analysed per hour. Combining with the separation techinique of ionic exchange, the method has been applied to the determination of traceIVamount of formaldehyde in the samples of air, paint and decoration board. The comparison and recovery tests have also been carried out, satisfactory results was obtained.Finally, on the basis of the third method, a FI catalytic spectrop...