Extracting Perfluorinated Compounds from Drinking Water – Why is it so Challenging?

For the past few years, news reporters have used words like “developing” and “emerging” and “crisis” to describe perfluorinated compounds. When you see adjectives like this, you can’t help but think “how did we not know about these PFC things before now?”

The truth is, these compounds have been produced for decades – some, for over half a century – and their chemical and physical properties are well-known. The strength of the carbon-fluorine bond in these compounds makes them heat-, water- and stain-resistant. Continue reading Extracting Perfluorinated Compounds from Drinking Water – Why is it so Challenging?

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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Tuesday Trivia – October 30, 2018

On the eve of Halloween, I find myself reminiscing about how I celebrated the holiday as a child. I remember the excitement of getting dressed up as my favorite animal or TV character, and bringing home a sack full of candy after a successful night of trick or treating. I also remember doing fun activities like making glow in the dark slime or ghost rockets.

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Tuesday Trivia – Answer for October 16, 2018

During National Chemistry Week, we’re continuing our trivia with an “Out of this World” focus.

Just a reminder of last week’s post:

An interesting study at the University of Georgia revealed the major component of interstellar clouds to be:

(a) Hydrogen and helium atoms
(b) Mothballs
(c) My dreams
(d) Ammonia
(e) Carbon Monoxide

Answer: mothballs

A handful of researchers measured infrared emission from some interstellar clouds and found a measurable concentration of gas-phase naphthalene, which is the main compound in mothballs. Just to clarify, naphthalene is pretty flammable so modern day mothballs are primarily composed of 1,4-dichlorobenzene, but older mothballs contained lots of naphthalene.

It’s only the third day of National Chemistry Week so you have 4 more days to celebrate the fact that chemistry is out of this world!

Join us next week to Expand Your Horizon!

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!

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

Pesticide Contamination – Is That Water Safe to Drink?

Have you ever spent the day walking through the woods, paused to take in the natural sights, smells and sounds of a babbling brook or flowing waterfall and thought….“I wonder how many pesticides are in that water?”

I recently experienced this when I escaped from the stress and chaos of real life to spend a day hiking through the woods. I mapped out my route, packed plenty of snacks and water, and tossed my camera (i.e. my iPhone which has a camera) into my backpack, and I was off. I wasn’t far into my hike before I heard the familiar rush of moving water. Excited at the thought of finding a natural stream or brook, I rushed toward the noise until I reached the edge of a bank that overlooked a flowing river. As I took in the breath-taking scenery, I found myself lost in thoughts like “I wonder how polluted this water is?” or “I bet there are pesticides in this water. Is it safe to drink?”

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Tuesday Trivia – October 2, 2018

Happy Tuesday! This week’s question will focus on one of the EPA methods used for extracting semivolatile organic compounds (SVOCs) prior to analysis by GC/MS. Are you ready to Expand Your Horizon?

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Tuesday Trivia – Answer for September 18

It’s now 1 week past World Water Monitoring Day – tell us what you did to celebrate in the comments below:

For those who took last week’s quiz to measure their water quality knowledge, read on. The questions and answers are below:

Continue reading Tuesday Trivia – Answer for September 18

Alternative to Sodium Sulfate Drying

If you are performing oil & grease analyses according to EPA Method 1664, you are familiar with the requirement to dry your extract prior to evaporation. There are those who might perform this step for reasons such as “this is the way we’ve always performed our extractions” or “the government-regulated method told me so” or “we have a giant container of sodium sulfate in the lab, so we might as well use it”; however, there is sound logic in removing water from your organic solvent prior to evaporating it.

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Tuesday Trivia Answer for September 11, 2018

On the eve of World Water Monitoring Day, we thought we would post last Tuesday’s response a day earlier! Celebrations for tomorrow’s epic event might otherwise interfere.

Just a reminder of last week’s post:

According to EPA Method 1664 A/B, n-hexane is used as an extraction solvent and must have a minimum purity level of…

Answer: 85%

EPA Method 1664 B outlines the use of n-hexane as an extraction solvent and Section 1.7.2 specifies a minimum purity level of 85% (Method 1664 A has the same requirement).

Believe it or not, hexane solutions typically contain a mixture of 5 structural isomers (i.e. same molecular formula, different arrangement of atoms). N-hexane is the longest (least branched) of the 5 isomers, which gives it the highest boiling point and lowest vapor pressure. Therefore, specifying a minimum purity level of 85% means you’re dictating that at least 85% of the solution must contain the x-hexane isomer.

Join us next week to Expand Your Horizon!