Detection Systems

Ultraviolet (UV)-visible based detection is used on many CGE applications. This type of system is applicable to a wide range of analytes, and is sensitive enough for many applications. However, the detection limit with UV is limited because of the small internal diameter of the capillary. For example, with this mode of detection, a DNA fragment of approximately 200 bp would need to have a concentration of about 0.5 mg/mL.[3] Therefore, detection systems based on laser-induced fluorescence are preferred if lower detection limits are needed.

Laser-induced fluorescence is also attractive because it allows the detection of multiple parameters in the same tube; that is, multiplexing and DNA sequencing become possible. DNA primers can be labeled with different fluorophores. On passing through the detection window in the capillary, the fluorescein-labeled polymerase chain reaction (PCR) products are excited by the laser and emit fluorescence with various emission spectra depending on the dye. The emitted fluorescence is detected by a CCD camera and the information is relayed to the computer, where data collection software processes it and displays the information as a graph of fluorescence color and intensity against size. Multicolor fluorescence detection also allows the use of in-lane size standards, thereby increasing accuracy and reproducibility when unknown samples are being sized.

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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