Scanning optics disadvantages

Each type of mass spectrometer has its associated advantages and disadvantages. Quadrupole-based systems offer a fairly simple ion optics design that provides a certain degree of flexibility with respect to instrument configuration. For example, quadrupole mass filters are often found in hybrid systems, that is, coupled with another surface analytical method, such as electron spectroscopy for chemical analysis or scanning Auger spectroscopy. 

TTie major disadvantage of the GeMSAEC is that although several analyses are run in parallel, the system is discontinuous and the rotor has to he stopped for reloading it is also difficult to carry out more than one type of assay in a rotor at any one time. This problem was overcome in the DACOS approach (Discrete Analyser with Continuous Optical Scanning) described by Snook et al. [17]. In this approach, reaction tubes are situated at the periphery of the rotor, which turns in discrete steps, a few degrees at a time, to enable... 

This chapter outlines emulsion characterization techniques ranging from those commonly found infield environments to those in use in research laboratories. Techniques used in the determination of bulk emulsion properties, or simply the relative amount of oil, water, and solids present, are discussed, as well as those characterization methods that measure the size distribution of the dispersed phase, rheological behavior, and emulsion stability. A particular emphasis is placed on optical and scanning electron microscopy as methods of emulsion characterization. Most of the common and many of the less frequently used emulsion characterization techniques are outlined, along with their particular advantages and disadvantages. 

Fourier Transform-Near infrared (FT-NiR). Only within the last 20 years has FT-NIR instrumentation (Fig. 4.1.14) become available. Even then, the first commercial instmments had a distinct disadvantage compared to grating-based scanning instruments. FT-NIR spectrometers employ an entirely different method for producing spectra. There is no dispersion involved. Energy patterns set up by an interaction with a sample and a reference and moving mirrors (or other optical components) produce sample and reference interferograms that are used to calculate the absorbance spectrum of the sample. 

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