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-NH, figure 11.15 The following amines that are in Figure 11.14 and Figure 11.21.

obtain satisfactory peak shape and resolution. In this case, a set of repeated analyses of the same sample has to be carried out for the determination of a broad spectrum of compounds.130 So, determination of AAs usually demands a derivatization step to lower the polarity of compounds, and to improve detection senility and selectivity.24

Many derivatization reagents for GC analyses of aliphatic primary amines by flame ionization detection (FID), electron capture detection, flame thermionic detection, GC-MS with selected ion monitoring (GC-MS-SIM), and electron-capture-negative-ion chemical ionization (GC-NICI-MS) detection with a modified thermal energy analyzer have been reported.131

Table 11.10 shows popular methods of amine detection used in GC analyses, while Table 11.11 shows examples of GC-MS analyses depending on the selection of column type, temperature, carrier gas, as well as the conditions of injection and detection.

C. CEandIC

CE has emerged as a powerful alternative to HPLC in separation science. CE methods afford highspeed and high-efficiency separations, utilize relatively inexpensive and long-lasting capillary columns, and consume small volumes of sample and reagent.99 CE is an extremely versatile separation method because selectivity can be changed essentially by addition of different modifiers to aqueous buffers or by changing buffer pH.94 In CE, where the most widely applied detection method is UV absorption, the small injection volumes and short optical path lengths (25 to 75 ^im) encountered in most systems make concentration sensitivity (using UV absorption) relatively low when compared with HPLC methods.99

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