Research On New Method Of Real - Time Rapid Analysis

Rapid real-time analysis has been one of the most important fields of modern analytical chemistry. In this thesis, the new formaldehyde detecting tube, dithizone membrance and chromium(Ⅵ) test paper were studied and prepared, and then the rapid real-time analysis methods respectively for determination of formaldehyde, mercury(Ⅱ) and chromium (Ⅵ) were established. In addition, a new spectrophotometry method based on silver nanoparticles for determination of captopril was developed. These news methods have been applied to determation of these susbstance in environmental and food sample.This dissertation consists of five chapters as follows:Chapter1:ReviewThe application and development of the real-time analysis were introduced. The progress about the determination of formaldehyde, mercury(Ⅱ), chromium(Ⅵ) and captopril in recent yeas was reviewed. The topic of the dissertation was proposed based on the existing literatures.Chapter2:Continuous flow-injection detecting tube for determination of trace formaldehyde in foodAccording to the mechanism of MBTH, a continuous flow-injection formaldehyde detecting tube which is based on reagent-immobilized in paper-base was proposed for the first time. The preparation conditions of detecting tube were optimized in detail. Under the optimized conditions, the absorbance was linearly proportional to the concentration of formaldehyde in the range of0.01～0.3μg/mL, the detection limit is0.006μg/mL. This detecting tube has been used for detection of formaldehyde in food with the satisfactory result.Chapter3:Development of dithizone membrance for determation of mercury(Ⅱ)The dithizone membrance for the determination mercury(Ⅱ) was prepared through dithizone nanofiber coated firmly and uniformly over the microporous cellulose membrane filter. Mercury(Ⅱ) concentration was obtained based on the absorbance of membrance using the remoulded reflectance-absorbance spectrophotometer. The calibration curve is linear over the range of0.5～10.Oμg/mL, the limit of detection was0.36μg/mL and the recovery is between98%and105%. The propose method has been successfully used for the determination of mercury(Ⅱ) in artificial waste water and rock samples.Chapter4:Rapid determination of chromium(Ⅵ) using test paperThe test paper for the determination of chromium(Ⅵ) was prepared based on the reaction mechanism between dipheylcarbazide and chromium(Ⅵ), a simple, rapid and inexpensive method for the determination of chromium(Ⅵ) has been proposed. In propose method, the concentration of Cr(Ⅵ) was received according to the mean gray value of test paper using scanner and photoshop software. Under the optimized conditions, the mean gray value of test paper was linearly proportional to the concentration of chromium(Ⅵ) in the range of0.5～25.0μg/mL and the limit of detection was0.27μg/mL. This method has been applied to determation of chromium(Ⅵ) in soil and rock samples with the satisfactory result.Chapter5:Colorimetric detection of captopril using label-free silver nanoparticlesA colorimetric method which based on label-free silver nanoparticles for the determination of captopril was developed in this study. Captopril can induce the aggregation of AgNPs, thereby results in their yellow-to-red color change and the absorbance decrease at λ395nm.The mechanism of the aggregation effect was discussed and the experiment conditions were optimized in detail. Under the optimized conditions, the absorbance was linearly proportional to the concentration of captopril in the range of1～35μg/mL with correction coefficient0.9984. The detection limit and RSD were0.7μg/mL and1.6%, respectively. The method has been applied to determination of captopril in tablets with the satisfactory result.