Retriever IV Fraction Collector User Manual - Isco

Retriever IV Fraction CollectorSection 3 Operating Procedures3.7 Void Volume Feature The Retriever IV includes a void volume feature which workswith an optional diverter valve (P/N 68-2177-002) to divert aninitial volume to waste prior to starting collection. This divertedvolume usually represents the column void volume which precedesany separations. But, the diverted volume can include boththe void and any unwanted eluent during the initial part of theseparation.The void volume feature has two distinct application advantages:1. It can be used to reduce clean up and glassware use byallowing collection in fewer tubes.2. It can effectively increase the capacity of the fraction collectorby allowing the diversion of an initial volume towaste.In operation, the void volume feature diverts flow via an optionaldiverter valve while the tubes and racks advance in normalfashion on the Retriever IV. When the end of the red rack passesunder the drop counter, the void volume diversion end and flow isdirected into the first tube after the red rack. The diversionvolume is set by the starting position of the red rack. Thediverted volume equals the programmed volume per collectingtube times the number of tubes from the starting point (after thePAUSE/RUN switch is switched to RUN, the first tube will beadvanced) to the last tube before the first tube of the red rack.Unlike normal collection, when the void volume feature is used,the red rack does not stop the collector until its second passunder the drop counter. On its first pass, the red rack stops thevoid diversion by switching the diverter valve from waste to collectionand the movement of the racks continues in a normalfashion until the last position of the red rack is encountered asecond time.NoteIn the TIME and VOL. modes, the void volume is measured bystandard means (minute counting or volumetric pump control).But when fractions are collected in the drop count mode, thevoid volume feature translates the programmed fraction dropcount into tenths of minutes during the void diversion. Forexample, if the fraction collector is programmed for 75 dropfractions during the void volume diversion, the collector willadvance tubes every 7.5 minutes. The void volume incrementper tube would be equal to the flow rate in ml/min times 7.5minutes. Once the void diversion is ended, the collector willresume normal drop counting. The void volume diversion featurecannot be used in conjunction with a Teledyne Isco volumeter.3-5