If you’re familiar with methylene chloride (which I’m sure you are since it’s one of the most widely used laboratory solvents), you know that it’s developed a reputation for being one of the “bad boys” of the solvent world. The bad press has certainly been earned. It’s been attributed to over 60 deaths in the last 4 decades. It’s also pretty aggressive – exposure to just a few ounces for a few minutes can be enough to cause severe damage or death. And since it’s a colorless liquid, an innocent-looking spill could be a severely harmful hazard.
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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:
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If you are tired of shaking liquid-liquid extractions (LLE) and want to move onto a technique that is less labor-intensive, solid phase extraction (SPE) may be your answer! There are manual as well as automated options available for solid phase extraction. It may seem like more work for your lab to move to a different technique, but what you gain in time savings may be worth it to you in the end.
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Have you ever stopped to enjoy a bright, vibrant sunset, only to have that really annoying friend interrupt your thoughts with a comment like “you know you’re just looking at all the pollution in the air, right?”
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On the surface, EPA Method 8270 seems pretty straightforward. The first version of this method was published over a decade ago and many environmental labs are processing samples according to the guidelines in this method.
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“Our laboratory uses organic solvents every day. Should we be concerned about solvent exposure?” I hear this question fairly often and the short and simple answer is: YES. But if this were a simple yes/no question, I wouldn’t have anything else to say, and this would be the shortest blog post that’s ever been written.
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“Why do I keep seeing background contamination from phthalate and adipate when I do extractions for semi-volatiles?” This is one of the most common questions I’ve been asked when I’m traveling in the field. It’s an issue I’ve come across in my own lab on occasion and if you can’t find the source of your contamination, it can turn routine application work into a troubleshooting nightmare. Given how often I’ve seen these compounds cause contamination issues, I thought I’d review some of the most common sources for these.
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Ugh…I think we can all agree that the worst thing that can happen when testing high profile samples is losing an extract due to phthalate contamination. Whether you are extracting 525.2 or 625.1 samples, phthalates can ruin your day and wreak great havoc, causing false positives!
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When juggling the responsibilities of working in a sample preparation lab as well as working as an analyst, it is very easy to get caught up in a never-ending cycle of samples. There is no situation “more frustrating” then when you have a bunch of wastewater samples that need to be extracted and analyzed ASAP and there is that one sample that is so much more challenging to extract than the others.
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Have you ever had days of extracting oil and grease samples and thought to yourself “there must be an easier way to work with wastewater samples”? Whether you run oil and grease samples by liquid-liquid extraction (LLE) or by solid-phase extraction (SPE) it can be challenging at times to efficiently extract 1-liter samples due to the sample matrix.
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Have you ever thought to yourself I wish there was one way to effectively extract all of our aqueous samples? For instance, there are several methods available to extract aqueous samples, such as extraction method 3510 liquid-liquid extraction (LLE), method 3520 continuous liquid-liquid extraction (CLLE), and method 3535 solid-phase extraction (SPE). Wouldn’t it be more convenient to use one extraction method within the lab for most if not all of your aqueous extractions?
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Working in an environmental lab requires a lot of concentration, both mentally and for the samples that you are working with. When New England finally begins to thaw and local companies rush to get their samples completed, a bottleneck that is usually experienced is the drying and concentration of so many samples.
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When preparing your extracts for analysis, it is important to know which instrument to use and why you should be using that specific one. Of course, we know that each EPA method dictates which analysis instrument must be used within each method, however, we will be determining why that option was chosen in the first place in this blog post!
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“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.
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Have you ever thought to yourself am I using the best solid phase extraction disk offering for my application? Or can our prep lab turn samples around more efficiently if we choose a different SPE disk platform such as a single-use disk holder instead of cleaning our reusable holders? Those are just a few questions I receive when working with sample prep solutions with customers when SPE disks are brought up in the conversion.
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IR technology is a rapid and convenient tool for both qualitative and quantitative analysis that has been around for over a century. Traditional IR spectroscopy relies on vibration energies from the molecular bindings, where IR emission is absorbed by the bond when it has the same frequency as the specific vibration or movement as the bond.
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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!
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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.
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It is question and answer time and we are starting with TurboVap® evaporators and their use in an environmental lab. The TurboVap® evaporation system by design utilizes a patented gas vortex shearing technology. You may be asking yourself, “what does that mean?” I know I did when I first heard about it! Read on to learn more about what this does for your lab evaporation.
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When working in a contract lab or any analytical testing lab, you may be prone to periods where it seems like there is never going to be a light at the end of the tunnel, as the samples just keep on coming in.
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It is that time of year again when laboratories are fulfilling accreditation requirements for the methods that they offer. One of the requirements that must be met for each method is called proficiency testing (PT).
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Have you ever put your water sample onto your Biotage® Horizon 3100 extractor and all your prewet/conditioning steps worked great and then suddenly, the water inlet valve opens, and nothing happens! This can be terrifying because a lot is riding on those samples!
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“Pesticides” is one of those terms that invokes a wide range of emotions in people. Some people smile when they think of the insecticides that keep their award-winning flower garden looking beautiful all season.
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Do you have issues seeing acceptable recovery of your phenols? I know I do. These compounds can be challenging to recover and quantitate, and are also found just about everywhere! Read on to learn a couple of fun facts about phenols, but first, let’s explain why phenols can be difficult to work with.
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The U.S. EPA monitors a variety of compounds that pose public health risks when they are present in our air, soil or water and they have spent decades publishing methods to help us extract and quantify those compounds. The 8000 Series EPA Methods describe the extraction and analysis of contaminants in groundwater and Method 8270 specifically covers semi-volatile compounds.
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Solid phase extraction (SPE) is a powerful sample preparation tool that makes it possible to extract semi-volatile organic compounds with varying physical and chemical properties. When used properly, this tool will simultaneously extract hundreds of analytes from the most challenging sample matrices. When used improperly – well, this tool can quickly become as effective as using a hammer to paint the walls in your house.
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In the first part of this 2-part blog series, I highlighted the improvements made by the EPA regarding the preparation and preservation of samples. In this post, I will focus more on the changes the EPA has made to Method 525 which affect the analysis of the prepared samples.
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There’s nothing more satisfying than successfully extracting a really challenging sample. Solid phase extraction (SPE) is a powerful technique for extracting semi-volatile organic compounds and hexane-extractable materials (HEMs). When the chemistry is tailored to meet the requirements of the application, literally hundreds of compounds can be extracted with a single pass of solution through an SPE disk.
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Since its release in 1995, EPA method 525.2 has been one of the most widely used methods for quantifying semi-volatile compounds in drinking water. Chances are, if you work for or own a drinking water lab, you probably analyze for compounds in this method – at the very least, you’re probably at least familiar with the method.
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On the surface, EPA Method 1664B seems pretty straightforward – use n-hexane to extract compounds (commonly referred to as “oil and grease”) from an acidified water sample. Evaporate the hexane from the extract, weigh the residue that gets left behind, and report that weight in terms of a concentration (often as mg/L of HEM).
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Phenolic compounds can be some of the most challenging compounds to extract from the compound lists in EPA Method 8270 and EPA Method 625.1. The recovery of these compounds suffer tremendously compared to some of the other target analytes on the list. So what exactly are phenols and why are they challenging to extract and quantitate?
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If you’re a laboratory that’s processing drinking water samples using solid phase extraction, you’ve inevitably gotten to the step in your procedure where you’ve eluted your analytes from your SPE media and you find yourself saying “How do I dry my extracts?”
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Per- and polyfluoroalkyl substances (PFAS) are a group of harmful organic compounds that are very persistent in structure. What this means is PFAS compounds accumulate in the environment over time as they do not break down easily. This makes it a concern to regulate and test these compounds as they have been shown to have adverse effects. One of the most common ways that someone would come in contact with PFAS is through drinking water.
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EPA Method 8270 is one of the 8000 series methods that outlines the preparation of wastewater samples. It is one of dozens of methods for processing wastewaters for semivolatile organic compounds (SVOCs), all of which fall under Method SW-846. Expand the graphic below to see the breadth of the method.
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Have you ever opened a jar of olives and noticed the shimmering liquid floating on the surface? Believe it or not, that liquid is actually residual oil that is given off by the olives themselves.
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If you’re reading this and raising your eyebrows, you’ve never had, what I like to call, the “grade discussion.” I don’t mean the discussion between high school or college students who are comparing grades after a big mid-term or final exam (although I used to do that too). I mean the discussion over the solvent grade you use in your laboratory.
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When in the lab I always try to streamline and improve workflows. One of the biggest bottlenecks in the lab I’ve experienced and maybe you have too, is the drying of sample extracts.
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Solid phase extraction is a powerful technique – it can be used to clean up the most challenging samples, and extract and preconcentrate hundreds of semivolatile organic compounds.
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As the seasons change, I’m reminded of a quote by Theodore Roosevelt and its significance to the air, land and water that sustain us.
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Have you ever wondered why solution flow rates are so important when performing sample preparation with solid phase extraction (SPE)? If you have, read on – I have the answer for you!
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In the world of solid phase extraction (SPE), the list of media that is available seems to be ever-growing. From polymeric stationary phases, to silica-based media, and even molecularly imprinted polymers specifically designed for target analytes. The possibilities seem endless.
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In a never-ending list of chemical pollutants, a compound that is gaining a lot of attention is 1,4-dioxane. In fact, New Jersey just became the first state to set regulations on the quantity of 1,4-dioxane that can be present in drinking water.
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Have you ever been extracting samples for oil and grease compounds using solid phase extraction (SPE) and thought, “why do I have to use all these different solvents, when I’m just trying to get my compounds to retain on, and then elute from, an SPE disk?”
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As a chemist, I’ve constantly stressed the importance of proper sample preparation. Whether I’m diluting, digesting, preconcentrating, extracting, or performing a combination of these, sample preparation is the key to making my analysis a success, yet it’s often the most challenging part of my workflow.
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