2 Replies Latest reply on Jan 12, 2018 12:52 PM by xiaoz

    Sample recovery issues in the SFC system

    xiaoz

      Has any one experienced sample recovery issues in the SFC system? For example, if you inject 10 ug , how much can you recover at the end? I have run some samples on SFC by-passing the column, and collected all the eluent at the end, and had only <60% recovery. Tried different composition and flow rates for mobile phase solvent composition and make-up flow but not getting any better.

        • Re: Sample recovery issues in the SFC system
          jhagel

           

          This is an unsupported configuration.  Agilent Fraction Collectors are designed and optimized for the collection of liquid fractions of a HPLC flow stream.  The HPLC flow streams are relatively low in velocity and exist as a single phase at the point of collection.  These flow stream attributes allow collection with high recovery rates and high purity. 

           

          Fraction collection of SFC effluent is not recommended on standard HPLC fraction collectors.  The SFC effluent expands as the carbon dioxide decompresses and returns to a gaseous state.  The result is a high velocity aerosolized flow stream that will spray out of the collector needle generally into collection vessels.  This aerosol will not be reliably collected and can easily contaminate adjacent vessels.  The aerosolized liquids and sample components that are not collected in vessels escape the collection vessel  – potentially external to the fraction collector itself.  As a result, collection efficiencies are poor and cross contamination is readily apparent.  For at least these reasons, one should not attempt to use a HPLC fraction collector with SFC.

            • Re: Sample recovery issues in the SFC system
              xiaoz

              Thanks, jhagel. But I didn't use the fraction collector, actually, I was not doing fraction collection. I just tried to collect the entire eluent out of SFC to see how much sample I can recover from the SFC system. The entire eluent from a single run was collected into a solution (the SFC outlet was submerged in the solution) in a large vial, so the aerosol spray can be minimized and if there was still any spray, most of it should be retained within the vial. Then I rinsed the vial wall to get everything into the solution, and then determine the entire amount in the solution. In this case, there might be still some loss due to aerosol formation, but I don't think it can be so significant.