Analytical aspects combined separation-detection methods

While an array of analytical techniques has been developed to study various aspects of cells (please see Cell Assays in Microfluidics), this entiy is focused on chemical cytometry. As mentioned above, chemical cytometry refers to methods in which intracellular constituents of a single cell are analyzed by means of a chemical separation. Such methods typically employ capillary electrophoresis for separations, combined with laser-induced fluorescence (LIF) or amperometry for detection. We refer readers to other entries for detailed descriptions of other methods used to evaluate the contents of cells ( Patch Clamp Measurements On-Chip, Mass Spectrometry on a Chip). 

The small inner diameter of the separation capillary used in CE implies a short optical pathway, and the consequent poor concentration sensitivity when conventional UV detectiOTi is used. To overcome this drawback several techniques have been developed some of them consist in application of general approaches that are not specifically addressed to CE analysis of alkaloids. One is the use of LIF detector for analysis of alkaloids with native fluorescence [68, 69] or after their off-line derivatization [64, 88, 112]. Sample pretreatment, a second major approach, is popularly employed in combination with sample extraction and can be conveniently applied in analysis of alkaloids because they can be easily retained in cationic-exchange sorbents in solid-phase extraction (SPE) mode [113, 114]. It may be interesting to focus on more specific aspects to detect very low levels of analytes using limited amoimts of samples to this regard chemiluminescence reactions and the use of online preconcentration methods will be considered. 

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