Several techniques have been reported for manipulations of cells and introducing the cells to the instrument for analysis. Because of difficulty in manipulation of a small single cell, relatively large cells like oocytes or neurons were chosen first as the model to test the reliability of a sampling technique. The neuron cells, from Helix aspersa, were homogenized in a microvial and then pre-purified for the analysis using microcolumn capillary liquid chromatography (CLC) and Capillary Electrophoresis (CE). Since this first assay, many advances in microscale separationsand instrumentations have proven that the information obtained from a single-cell is much more valuable as compared to the information obtained from a heterogeneous population of cells. While chemical analysis of single cells has a long history, the type of cells and the number of chemical components that can be analyzed are rapidly increasing thanks to the advancement in instrumentation. However, a total analysis and complete chemical inventory of a single cell and cell-by-cell monitoring of a chemical of interest is a dream of analytical chemists, biologists, and biotechnologists. So far, single cell analysis has targeted a classof compounds in a cell for partial analysis and total analysis has a long way to go before being feasible. In this presentation, flow cytometry and CE will be discussed inmore details because the former technique is widely accepted in scientific community for whole cell sampling and the later one could beused for almost all different types of sampling. While a dilute suspension of cells is pumped through a capillary for whole-cell sampling in flow cytometry, the CE separation requires drawing the entire cell into an etched capillary via a micromanipulator and a microscope to control the sampling process.After sampling a plug of lysate, like a surfactant, is injected to lyse the cell inside the capillary for the release of its contents for further analysis in CE. As with many techniques involving single cells, sample throughput is an important criterion to be considered. Flow cytometry and CE are the two extreme cases because the former is a very high throughput technique while the latter is a very low throughput one. The obvious advantage of whole-cell sampling is that it allows for simultaneous detection of multiple species inside a single cell but information obtained about the compartmentalization of the subcellular compounds detected is limited. Hence, I will discuss methodologies to probe cytoplasm and subcellular components to complement the knowledge obtained from whole cell sampling. Obtaining subcellular information from single cells suffers from low throughput due to the tedious nature of selecting the area of interest inside a single cell. You could imagine how it would be possible to target just one mitochondrion inside a single cell and sample that targeted mitochondrion into a capillary to get more information about the electrophoretic mobility of the organelle and correlate it to the surface charge and size of the mitochondria. So far, histochemistry has been used for this purpose but the information from histology is very qualitative. However, I have developed new sampling strategies that hold promise for small cells and subcellular sections. I will discuss direct sampling of subcellular compartments, mitochondria, from muscle tissue cross sections and the Sampling Device would be introduced in more details.

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