Extractable Petroleum Hydrocarbons (EPH) Fractionation and Bottlenecks in the Laboratory

Anyone familiar with EPH methods such as those developed by the Massachusetts or New Jersey Department of Environmental Protection is familiar with the long and grueling process of fractionation. For those unfamiliar, an EPH or Extractable Petroleum Hydrocarbon is an extraction that essentially occurs in two distinct parts: the initial extraction & concentration and the fractionation of that initial extract into the aromatic and aliphatic fractions and then concentration again.  EPH is a method that replaces the TPH (Total Petroleum Hydrocarbons) or 8015 methods and allows for the calculation of specified carbon ranges giving you a more accurate assessment of potential health risks.

The fractionation process can be a particularly frustrating procedure for laboratories that run this methodology.  Many labs will not utilize vacuum to facilitate this fractionation process and will rely on gravity to allow the flow of the solvents through the silica gel cartridge.  This process does take quite a bit of time and it is driven by manual techniques. For example, if I were to perform a full aqueous extraction for EPH using 8 separatory funnels, it would take me the better part of a day and a quarter of time invested to get those 3 quality control and 5 customer samples extracted.  The fractionation portion itself would take up more than half of that time and in the end, I would only complete 5 customer samples to be analyzed on the GC FID that day.

Don’t even get me started on having to make sure your solvent measurements are accurate from lot to lot by performing a fractionation check for each new lot of cartridges only to have it fail and prevent me from making any progress on my work.  Another huge bottleneck in completing your extractions was when fractionation did not work perfectly, and you saw breakthrough of one set of compounds into the wrong side of the fraction and you had to perform a re-fractionation.  It was extremely challenging having to run back to the extractions lab and perform the whole fractionation process over again especially when you had deadlines.

So, as you can see fractionation is already a bit of a bottleneck even without the numerous issues with variation of media between different lots of cartridges. To add to that headache, the technique varies from technician to technician meaning that if your normal lab tech is out sick and someone less practiced in the art of fractionation has to fill in you may even see different results from what you expect.  As someone who has used a variety of different fractionation cartridges throughout the years, the main thing I want is consistency, so you don’t have to waste any more time on an already long process.  Out of all the brands I’ve encountered while working in the laboratory, the  Biotage Isolute EPH cartridge has been the Advil to help alleviate my headache.

With the Biotage EPH brand cartridge, I hardly saw a difference in data from when a 3-year veteran fractionated compared to the technician that I just started training 3 weeks earlier. As an added benefit the fractionation checks were a breeze and inspired confidence that each lot of cartridges were consistent and would not cause us to drop whatever we were doing to re-fractionate a failed sample. Even during the best stretches of fractionation with other brands, I still experienced occasional breakthrough and fractionation check issues requiring us to frequently adjust the method. Isolute’s proprietary blend of silica and alumina helped eliminate one of my worst enemies of sample breakthrough and helped to keep the extractions lab moving forward instead of stuck in neutral.  Click here to download a chemistry data sheet on the Isolute EPH solid-phase extraction column.

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