The Development Of Small Droplets Spectrophotometer

Traditional spectrophotometry is a matured technique both in analyticalmethodologies and instruments. However, it is usually not suitable for some on-linecontinuous monitoring purpose mainly because the optical cell may be stained bythe colorized analyte. Liquid drop is an old technique with wide applications, which is featured withexcellent reproducibility, renewability, defined volume, and lack of containmentwall. When a liquid drop is used as an optical cell in an optical analyticalinstrument, the windowless nature of such a cell can avoid scattering andbackground fluorescence due to the windows in a fluorescence detection system. Inaddition, the problem associated with chemical-stained windows will be solved,and this facilitates its use in on-line monitoring systems. Traditional liquid drop asan optical cell, however, it suffers from short optical path, thus somewhat losing thesensitivity of measurements. In this research, a simple flow-through type cell wasdesigned and used as a prolonged "liquid drop", which is called a pseudo liquiddrop here, in an attempt to solve the problem of short optical path while keep thewindowless feature. Various charge coupled devices (CCD), as multiple channel optical detectors,have been widely used in many spectroscopic techniques. CCDs with high spectralresolution and sensitivity have been successfully used in modern commercialatomic or molecular spectrometers. A handheld spectrophotometer was assembled, in which a drop head or a四川大学硕士学位论文flow-through type cell replaced a conventional cell and an inexpensive CCD wasused as a portable detector. The determination of potassium permanganate withsingle channel manifold and the determination of formaldehyde with dual channelmanifold were acquired using the handheld spectrophotometer. The limits ofdetection of potassium permanganate and formaldehyde were found to be 1.1 mg/Land 0.05 mg/L, respectively, with the liquid drop, and 0.19 mg/L and 0.01 mg/L,respectively, with the pseudo liquid drop. Finally, the application of metal (tantalum, molybdenum, and platinum) devicesis reviewed in atomic absorption spectrometry, atomic emission spectrometry,atomic fluorescence spectrometry, inductively coupled plasma atomic emissionspectrometry and inductively coupled plasma mass spectrometry.