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 gruelling process of fractionation. For those unfamiliar, with EPH or Extractable Petroleum Hydrocarbons it is an extraction that essentially occurs in two distinct parts: the initial extraction & concentration and then the fractionation of that initial extract into the aromatic and aliphatic fractions followed by 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.

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EPA Methods and the Use of Drying Techniques

Do you ever tire of using sodium sulfate to dry your extracts?  I know I do.  That is why, whenever I get the chance to avoid using it, I do.  The worst experience when using sodium sulfate is when you do not use enough of it, and the sodium sulfate reaches its maximum capacity leading to water breakthrough into your ‘what was supposed to be a dried extract.’  Then, you must dry the extract again with more sodium sulfate.  When you are a high throughput lab, redoing steps is not ideal.  Unfortunately, EPA Methods 525.2 and 525.3 require sodium sulfate drying as the drying technique, to name a couple, but not all EPA methods require sodium sulfate for drying.  That is why when there is an alternative technique available and you are permitted to use it, why not use it?!

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SLE, SPE and LLE – How are Those Different?

Liquid-liquid extraction (LLE), supported liquid extraction (SLE), and solid-phase extraction (SPE) have existed for decades and if you’re doing organic sample preparation, you’re probably quite familiar with at least one of these techniques.  But are you familiar with all of them?  How are they similar?  How are they different?  Let’s review! Continue reading SLE, SPE and LLE – How are Those Different?

To Be or Not to Be Water Miscible

“Oh my!  This is crystal clear!” – said nobody who has ever read through an EPA Method.

For anyone who processes samples in an EPA-regulated laboratory, you know that these methods can be very specific in some spots, and incredibly vague in others.  The complexity worsens if you’re following one method for sample cleanup and another method for sample preparation and data collection.  Consult this handy infographic to make sure you’re following the right methods for sample cleanup, processing and analysis.

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Spooky Stories or Laboratory Mishaps?

“There is a child in every one of us who is still a trick-or-treater looking for a brightly-lit front porch.” – Robert Brault

It’s Halloween!  I assume you’ve carefully assembled your favorite movie character, comic book superhero or animal costume for a night of spooky fun.  If you’re me, this is the day you get to wear your superhero cape out in public.  As an applications chemist, I consider myself to be a bit of a superhero – but a humble one, as I wear my cape underneath my t-shirt and lab coat.  I consider myself to be a superhero when I’m able to use my background and my experiences to think quickly on my feet and help troubleshoot challenges that chemists face all the time.  It’s one of the best parts of my job and I’m thrilled each time I get to wear my cape – metaphorically speaking.

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Are You Contaminating Your Samples During Evaporation?

“Water in my extracts again?!?!”

How many of you have been in that position?  You’ve worked hard to extract your samples, you’ve dried your extracts to remove the last droplets of water from your organic solvent – only to add that water back in during your evaporation step!  There are fewer frustrating situations than losing a set of extracts in this manner.

If you’re like me, you work hard, follow all the precautionary step-by-step procedures to carefully produce extracts in a timely fashion.  It’s frustrating to think that a whole day’s work can be ruined with just a few milliliters of water.  When you see the water, you make an attempt to remove it and save your extracts, but there’s no guarantee that it’ll work.  Is there any way to avoid this?

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10 Facts About Pesticides You Didn’t (Want to) Know

Pesticides have been widely used in the U.S. for decades to combat everything from weeds to insects to bacteria.  These compounds allow farmers to cultivate acres of successful crops and keep food on our dinner tables.  But every chemical poses a risk, so I always like to familiarize myself with the chemicals I’m being exposed to, in order to make informed decisions about the health and safety of me and my family.  Here are a few facts about pesticides I thought I’d share – just in case you’re on the same fact-finding journey I am.

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UCMR 5 – Will PFAS Make an Appearance?

If you’re reading this blog and hoping for a sneak peek at the list of contaminants that will be on the next UCMR list, you’ll want to keep reading…

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An Alternative To n-Hexane For Doing Oil and Grease Extractions

Volatile.  Flammable.  Skin irritant.  Respiratory irritant.  Possibly fatal if swallowed.  For those of you processing samples according to EPA Method 1664B, you’ve seen these hazard descriptions before – on the safety data sheet (SDS) for n-hexane.  For those of you who aren’t familiar with (or have forgotten about) the hazards related to n-hexane, those are just a few.  It also smells unpleasant and could explode if heated.  It’s a relatively unpleasant organic solvent to work with and it begs the question:

Is there an alternative?

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