No matter what your sample will be tested for, if you are extracting with liquid-liquid extraction (LLE), solid phase extraction (SPE), accelerated solvent extraction (ASE) or microwave, your sample's extracts will appear to look clean or dirty.
But you cannot determine by the naked eye if the extracts will cause a problem with your analytical detection instrument unless it is pure oil or very viscus. If you do choose to run samples straight on an analytical instrument, then you are potentially risking a lot of extra time for an analyst. This is because to determine the targeted analytes one must limit potential interferences that could cause poor quantification, cross contamination, or even worse, take down your analytical instrumentation altogether. One way to prevent crippling the sample throughput in your laboratory from untimely downtime is to consider using a sample clean up method. Of the many types of cleanups available, one of my favorites is to use florisil.
If you have never considered using a cleanup, then why florisil? Well, florisil is a normal phase media that is regularly used for cleanup of hydrocarbons such as pesticides, PAHs, and PCBs from polar compounds. An important fact about florisil cleanup with sample extracts is if your extracts, or the media itself is not fully dried and contains water or moisture the florisil media will be less effective at cleaning your extracts.
I use florisil when I am working with a Gas Chromatography/Electron Capture Detection (GC/ECD) system to determine pesticides. If you find yourself having trouble identifying analytes due to interferences within the sample extracts, then it may be in your best interest to utilize a cleanup method such as florisil.
Implementing a florisil cleanup within your workflow will help confirm the identification of an analyte by eliminating interferences from the matrix. Analytical instruments such as a GC/ECD are prone to both positive interferences and negative interferences from signal suppression caused by hydrocarbons. Oily and viscus samples will cause retention time shifts that may make confirmation of identity difficult across the board. Plus, these samples could also cause potential cross-contamination from run to run.
If your lab is considering implementing a sample cleanup method in your sample prep workflow, there are a few options to choose from. First, cleanup techniques can be accomplished by either using a glass column packed with florisil in your lab or by using solid-phase extraction cartridges containing florisil. If you are leaning towards packing your own columns, the big thing to consider is manual prep inconsistencies such as differences in the media mass used, the tamping force, and the general build of the columns. All of these can affect the process from sample to sample and add to the overall process time which is not cost-effective.
I have found that it is much easier to use vendor cartridges for several reasons. One is they are more consistent. This is due to the fact they are machine assembled, and each component has been tested for quality and consistency. The other big benefit with vendor cartridges is that you can semi-automate or even fully automate the cleanup procedures and, in some cases, have entire sample batches cleaned up. I like utilizing batch cleanups with my workflow as it can lead to streamlining multiple processes. For instance, if I use a Biotage® Extrahera™ to clean twenty-four samples at once with 6ml cartridges I could then take the entire extract tray with my florisil cleaned extracts and place them directly into a TurboVap® EH and concentrate all twenty-four at once. This would eliminate any potential analyte loss with twenty-four transfer steps and any potential sample mislabeling. It has been a real game-changer for me by avoiding transfer steps while keeping my sample accountability in check as my extract trays are labeled.
By implementing a florisil cleanup step in your workflow you will be removing matrix interferences for enhanced analytical quantification while also making it much easier to identify analytes and therefore more enjoyable for the analyst. If you are looking for ways to increase productivity and streamline workflows with extract drying and concentrating options in your lab please read one of our past blogs on overcoming drying and concentrating bottlenecks in the lab. You just may find the missing piece of the puzzle to unlock your labs full potential. Download our latest Guide to Environmental Applications.