Understanding SPE Retention Mechanisms

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.  Some of my preparation procedures are simply daunting – a series of challenging, time-consuming steps with multiple opportunities for error or cross-contamination.  On top of that is the multitude of parameters that must be selected.  Questions such as “what should the pH be?”, “which solvents should I use?” and “what should my sample volume be?” are a few of the many, many parameters that must be optimized.  When you look at all the opportunities for something to go wrong, sample preparation can seem very overwhelming.  While powerful, sample preparation becomes a lot less complicated when you understand the science behind what you’re trying to accomplish with this step.

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What does a thermistor do anyway?

It is easier to understand something when you know what the actual word means.  Thermistor is a portmanteau (yes, sometimes I do pay attention to linguistics) of the words thermal and resistor.  This means that when a thermistor is heated, its resistance is either increased or decreased based on the properties of that particular thermistor.  This property makes it very useful for many different applications all over the world.  But thermistors are most useful, at least from my perspective, when they’re used in automated solid phase extraction systems.

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The Chemistry of SPE

New year – fresh start

If you’re like me, you start the new year off with a list of resolutions for the coming months – resolutions to be more fit or to secure a promotion at work or to reduce your carbon footprint. Whether you’re trying to improve your health or further your career, these are the types of goals that I like to refer to as getting “back to basics” because they require you to start with a solid foundation which you can build on to achieve success.

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Paraquat and Diquat Use in Pesticides

If you read one of my earlier posts on pesticide contamination in drinking water,  you may have started to make a mental list of all the compounds you’ve heard or talked about in reference to their use in pesticides. If so, two of those compounds were likely paraquat and diquat.

These compounds are complex dipyridyls but with chemical names like 1,1′-dimethyl-4,4′- bipyridilium dichloride salt and 1,1′-ethylene-2,2′-bipyridilium dibromide salt, I assume you’re like me and refer to them as paraquat and diquat, respectively. Dipyridyls are effective herbicides which is why they are so commonly used to eradicate unruly weeds. Unfortunately, many herbicide products are non-selective and will kill a variety of plants, flowers and grasses along with those pesky weeds.

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Changes to EPA Method 625 – How do They Affect You?

With the prevalence of contaminants in wastewater today, it is important to have a method for properly extracting and quantifying those compounds, to allow our wastewater treatment plants to remove them during the treatment process, when and where they need to.

The U.S. EPA has written a number of methods for determining contaminants in wastewater – compounds from organophosphorus pesticides (Method 614.1) to organochlorine pesticides (Method 608.3) to chlorinated hydrocarbons (Method 612) have EPA-published methods for guidance. The method I want to focus on here is that for determining bases, neutrals and acids (Method 625.1) and I’m highlighting it because there’s been a change in how this method can be executed, which could have a significant impact on your laboratory. Curious about what I’m alluding to? Read on!

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5 Myths About Oil & Grease

If you were ever a fan of the show MythBusters, you can appreciate the hours I spent watching myths being confirmed or busted in the most entertaining ways. For me, this show was appealing because the scientific theory was used to design and test experiments to produce facts about interesting phenomena such as: humans use only 10% of their brains, a household vacuum cleaner can generate enough suction to lift a car into the air, or a goldfish’s memory is only 3 seconds long.

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Extraction of 1,4 Dioxane from Drinking Water

1,4 dioxane – sometimes referred to as just dioxane – has gotten a lot of press since the U.S. EPA added it to the third Unregulated Contaminant Monitoring Rule (UCMR 3). It is a relatively common solvent in analytical laboratories; however, it also finds use as a stabilizer for manufacturing items such as shampoo, cosmetics and food additives. After the EPA deemed this compound “likely to be carcinogenic to humans” and found it in a number of groundwater sources across the U.S., 1,4 dioxane was added to the UCMR 3 list and is now a regulated, routinely monitored contaminant.

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SVOCs – Should I be Worried About Those?

If you’ve ever taken on a home renovation project and needed to purchase wall paint, you may have looked at “low VOC” or “no VOC” paint. Even if you don’t know what VOCs are, you are likely familiar with the terrible, headache-inducing smell that greets you when you pry the lid off a new can. Not only is the odor unpleasant, but the fumes are harmful when you breathe them in over a prolonged period of time.

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PFCs in the Antarctic

“Magical.”

If I had to use a single word to describe aquariums, it would be “magical.” Whether you’re a child or a child at heart (like me!), it is easy to get lost with the turtles, sea lions, eels, sharks and any other aquatic life you can imagine. The exhibits closely mimic the sights, sounds and smells of each aquatic environment – so closely, that you might think you’re out in the ocean or in the middle of the Antarctic.

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Fats, Oils and Grease, Oh My!

If you are unfamiliar with terms like “fatberg” and “FOG,” you might not realize the significance and environmental ramifications of this phenomenon. Your perspective will change if you look through recent news articles where fatbergs have blocked and damaged sewer systems in major cities.

Photo credit: Thames Water

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