Analytical methods magnification

The basis for effective F(+) separation was discussed in Section 7.7. It was pointed out that slight enrichment in the direction of a field or across an interface could be converted into an effective (sometimes spectacular) separation along a flow axis perpendicular to the axis of enrichment. The magnification of enrichment by flow is sufficiently large that many components can be separated in a single run. This is best illustrated by chromatography, the most important analytical separation method now in use. Another F( + ) approach of analytical importance is field-flow fractionation, a relatively new family of techniques applicable to macromolecules, colloids, and related materials. 

A Renishaw Raman Microspectrometer, model RM-2000 equipped with Leica microscope, lOx magnification objective and CCD detector was used to study the signal enhancement of analytes deposited on stainless steel (ss) plates by the direct application of silver colloids. The spectra were obtained in the range of 600-1800 cm nsing one acquisition and 3 s of integration time (Fig. 1). Spontaneous Raman spectra were obtained from pentaerythritol tetranitrate (PETN) high explosive (HE) and from SEMTEX, a PETN based explosive formulation. PETN was synthesized according to the method described by Urbanski (16). 

The EPA has issued two methods for analysis of waterborne asbestos. Method 100.1 [20] is a research method developed in 1984 that measures and counts all asbestos fibers longer than 0.5 pm. Only 0.1 pm PC filters are allowed by this method. Method 100.2 [24] was published 10 years later to reduce coimting to only fibers longer than 10 pm (in accordance with the EPA MCL) and to incorporate many of the analytical shortcuts of the widely used AHERA TEM method for measuring airborne asbestos concentrations [25]. Use of MCE or PC filters is allowable and minimum analytical magnification is 10,000 x versus 15,000 x for Method 100.1. 

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