Instrumentation Considerations

This technique assumes a Gaussian spreading function and thus does not take into account skewness or kurtosis resulting from instrumental considerations. It can, however, be modified to accommodate these corrections. The particle size averages reported here have been derived usino the technique as proposed by Husain, Vlachopoulos, and Hamielec 23). 

The short (UV) wavelength limit of the optical range is imposed by instrumental considerations (spectrophotometers do not usually work at wavelengths shorter than about 200 nm) and by the validity of the macroscopic Maxwell equations. These equations assume a continuous medium in other words, that there is a large number of ions within a volume of. The long (IR) wavelength limit of the optical range is basically imposed by experimental considerations (spectrophotometers work up to about 3000 nm). 

CE has been included as a distinct analytical technique in a general monograph in the Ph.Eur., JP, and USP. These monographs have been harmonized and at present only some minor differences exist between the different pharmacopoeias. They give an overview of the general principles, instrumental considerations, and the different separation modes. Also, attention is paid to quantification and system suitability aspects. 

Johansson, I. M., Huang, E. C., Henion, J. D., and Zweigenbaum, J. (1991). Capillary electrophoresis-atmospheric pressure ionization mass spectrometry for the characterization of peptides. Instrumental considerations for mass spectrometric detection. /. Chromatogr. 554, 311 — 327. 

Common characteristics of all viable process Raman instmments include the ability to measure at multiple locations, simultaneously or sequentially, and in a variety of electrically classified or challenging environments with no special utilities. The instrument must be reasonably rugged and compact, and not require much attention, servicing, or calibration [19]. Modem process Raman instruments essentially are turnkey systems. It is no longer necessary to understand the optical properties and other instrnment details to suc-cessfnlly nse the techniqne. The general design options will be described briefly, bnt more information is available elsewhere [20,21]. This section will focus primarily on special instrumentation considerations for process installations. 

Kinetic measurements by EPR are difficult, primarily because of the instrumental considerations mentioned in Sections V.B and V.C. Nonetheless, the specificity of EPR toward paramagnetic species has prompted workers to measure reaction rates of radicals generated by both in situ and external electrolysis, using both static and flowing solutions. 

In the first place column characteristics will often be determined by practical conditions, such as availability of columns and materials and instrumental considerations. 

As an example, we assume a gradient from 100% water to 100% methanol in 20 minutes, on a column with a t0 value of 1.5 min. Now a solute that elutes with a retention time t = 15 min (t is the retention time under gradient conditions) is expected to yield fc=3 at the composition that was reached at the column inlet at r = 15 - 2x1.5 =12 min, which is 60% methanol, 40% water. Assuming that there is no delay time due to instrumental considerations, this is the composition at the start of the column, but not at the end. One and a half minutes (t0) later, this composition will have reached the end of the column. 

Instrument Considerations when Using Ultra-High Pressures... 

N. M. Djordjevic, P. W. J. Eowler, and F. Houdiere, High temperature and temperature programming in high-performance liquid chromatography instrumental considerations, 7. Microcol. Sep. 11 (1999), 403-413. 

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