Topics - Fraction Collector
A fraction detector is a device that allows regular or specified samples to be taken from a column eluate and stored in a retrievable form. The storage vessels are usually small sample tubes or vials that are oriented in a rotating disk or in a moving belt, there movement usually being controlled by a microprocessor. On receiving a signal from the microprocessor, the next vial is placed under the column outlet and the eluate collected until receiving another signal from the computer. Once the properties of the chromatogram that describes the separation has been ascertained, then the collection program can be defined. The fractions can be collected on a basis of time either at regular intervals or a specific times to collect specific peaks. Alternatively the fractions can be collected by monitoring the detector output and when a peak starts to elute the fraction collector is activated and the peak collected in a specific vial. When the peak returns to base line the column eluate is then directed to waste until the next peak starts eluting. Fraction collectors are in common use with most liquid chromatographs. They are used to collect samples for further purification, subsequent exmination by spectroscopic techniques or for biological or organoleptic testing.