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.
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.
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.
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!
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.
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.
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.
Solvent drying is a key step in many laboratories that are using organic solvents for syntheses and extractions. In the case of hexane extractions during oil and grease measurements, this step is necessary to ensure that the extracts are accurately dried, concentrated and weighed.