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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In Defense of Methylene Chloride

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.

Though it’s a solvent with a bad reputation, I feel as though I need to come to its defense, because it’s a necessary solvent for a lot of laboratories doing sample preparation and extractions of volatile and semi-volatile organic compounds.  EPA Methods 8270 and 625.1 (just to name a couple of examples) require the use of methylene chloride during the extraction process.  This solvent is critical for accurately and reliably extracting the hundreds of compounds that are outlined in those methods.  Methods like 8270 and 625 are just 2 out of dozens and dozens of methods that are designed to guide labs in extracting compounds that are contaminating our air, soil and water.  So, if you ask me, methylene chloride is one of my heroes.  The key is to handle it with caution and respect.

Treat Methylene Chloride with Respect

Almost all laboratories use dangerous reagents and chemicals in their day-to-day or month-to-month operations.  Anyone who has used a blast shield when using perchloric acid or suffered skin burns from an aqua regia spill knows just how dangerous some of these chemicals can be.  But we can’t always avoid using them.  If we could, alternative laboratory procedures would have been developed a long time ago!  Since we find ourselves in contact with these chemicals from time to time, it’s important to respect them.  It’s also important not to fear them.  That may seem like a strange thing to say since the effects of these chemicals are kind of scary.  But fear can cause us to react physically (to become paralyzed or to shake violently).  Fear can cause us to do something quickly, without pausing to think through all the possible consequences.

Imagine yourself using hydrofluoric acid in the lab.  (For anyone who’s unfamiliar, it’s a great solvent for dissolving silica-based compounds, but it’s also a calcium-loving chemical that will eat through your bones if it comes into contact with your skin – not cool!)  Now imagine yourself working with that acid and you spill a small amount as you’re pouring it from the solvent bottle to a graduated cylinder.  If fear takes over, you’d see the acid splash onto your skin and you’d probably react by panicking, hyperventilating and crying.  If you’d been trained to treat the acid with the respect it deserves, you’d see the acid splash onto your skin and you’d probably react by grabbing the nearest tube of calcium gluconate, applying it generously to your skin, then make your way quickly to the nearest hospital.

Now let’s go back to methylene chloride and review what you need to know to handle it with the respect it deserves.

Know Your Exposure Routes         

If you’re using a chemical in the lab, the best way to learn its potential to harm you is through its safety data sheet (SDS).  Here’s an example SDS for methylene chloride.

It’s never a bad idea to skim through the SDS periodically to refresh your memory on how to handle the chemical properly and how to react if you become overexposed to it in some way.  But if this is your first time working with a particular chemical, you should definitely review the SDS and ask questions if there’s anything in it that doesn’t make sense or doesn’t seem clear to you.

Here are a few general tips to help make sure you handle methylene chloride with caution and react properly if an accident occurs:

Ingestion

Presumably, this is the least likely way for you to be exposed to methylene chloride, but accidents are unpredictable – hence why they’re called accidents.  If methylene chloride splashes anywhere near your face and mouth, make sure you wash your face really well with soap and water and rinse out your mouth.  Then drink lots and lots of water.  And when you think you’ve had enough water, drink some more.  Methylene chloride is one of the solvents that’s harmful if you try to throw it up.  It’s safer to let your body handle the solvent the way it would handle all the liquids you drink during a normal day – as long as there isn’t too much solvent for your body to handle.  That’s where the water comes into play.  Drinking a lot of water dilutes the amount of solvent that’s in your body and helps to flush it out of your system.

Absorption

We always work diligently to avoid spills in the laboratory, but accidents happen – flasks tip over, beakers crack and leak, splashes occur as you’re pouring from a large stock bottle to a small graduated cylinder.  If a spill or splash occurs and any part of you comes into contact with methylene chloride, wash it off immediately with soap and water.  If any of your clothing gets splashed, get it off your body as quickly as possible and wash it thoroughly before you put it back on.

Inhalation

This route of exposure is the most dangerous and the exposure route responsible for almost all the deaths that have been attributed to methylene chloride.  Methylene chloride has a noticeable smell, but if you work with organic solvents in the lab, you’re used to being around solvents with noticeable smells and you may not necessarily distinguish those coming specifically from methylene chloride.

Methylene chloride vapors act quickly and attack via 2 different mechanisms.  When we inhale methylene chloride vapors, our body converts it to formaldehyde and carbon monoxide to metabolize it.  The carbon monoxide displaces oxygen in our body and eventually causes us to suffocate.  It doesn’t take much carbon monoxide to develop before you’ll start to feel dizzy and eventually pass out.  Once you’re unconscious, suffocation and death isn’t far behind.  At the same time, the methylene chloride vapors can overwhelm your nervous system and cause sensory problems or cognitive impairment.

Given the inhalation hazard, methylene chloride should always be handled in well-ventilated locations, but if you become exposed to the vapors in some way (accidentally, of course!), find some fresh air fast.  Once you’re breathing the safe air you’re used to breathing, your body will slowly replace all that carbon monoxide with oxygen and get rid of the carbon monoxide that was building up.

Know the After-Effects

Knowing what to watch for after an exposure is just as important as knowing what to watch for at the time of exposure.  It’s not always easy to figure out how much methylene chloride you came into contact with during an accident.  How many milliliters of solvent splashed onto your arm?  How concentrated were the vapors in the air when you started feeling dizzy?

And even if you did know the answers to those questions, each person’s reaction to the solvent could be a little bit different.  So even if you’ve reacted to an accident exactly as you should have, it’s important to know what to watch for in the following days.  Did a rash develop on your skin the next day?  Did you develop a sudden headache or are you feeling more tired than usual?  Many SDS sheets have a section that includes notes for a physician to help them treat someone who has been exposed – methylene chloride is no different.  Make sure you’re familiar with the symptoms and effects that are described for physicians and watch for those in the days following an accident.

Know How to Be Safe

The key to working safely with methylene chloride – or any solvent, for that matter – is knowing how to be safe around it.  Knowing how to react to an accident is certainly part of that.  But knowing how to be around it, in general, is part of being safe.  How should it be stored?  How should it be transported?  How should it be disposed of?

When you’re actively working with it, how should it be handled?  Are there certain materials that should be avoided (should you avoid using plastic labware, for example)?  Are there solvents that will react violently with methylene chloride?  Will it react to moisture or oxygen in the air?  Will it react if it’s exposed to light?

It’s important to know this information before you even step foot into the lab.  The safety data sheet will help answer all these questions, so keep a copy handy, and proceed with caution – not with fear.

Feel free to share your “bad boy” solvent examples in the comments below!

Environmental Pollution – Are We All Doomed?

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?”

I used to wonder how someone could focus on pollution while looking at a stunning landscape, but it’s becoming a topic that more and more people are thinking about.

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5 Sources of Phthalate and Adipate Contamination You Probably Didn’t Know About

“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. Continue reading 5 Sources of Phthalate and Adipate Contamination You Probably Didn’t Know About

Everything You Wanted to Know About EPA Method 8270 But Were Afraid to Ask

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.  The EPA summarizes the goals of the method in a single sentence on their website:

“This method [is] for analysis of solid, non-drinking water, drinking water and/or wipe samples containing select semi-volatile organic compounds.”

Continue reading Everything You Wanted to Know About EPA Method 8270 But Were Afraid to Ask

6 Changes to EPA Method 8270 That You May Not Be Aware Of

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.  The EPA has been monitoring semi-volatile compounds in solid waste, soils and groundwater for almost 40 years, and Method 8270 has undergone several revisions during that time.  For example, revision C allowed air samples to be included in the list of sample matrices that can be analyzed under this method.

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7 Horrible Mistakes You’re Making with Solid Phase Extraction

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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Improvements in Processing Drinking Water Samples by Method 525, Part 2: Extraction Procedure

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.

Continue reading Improvements in Processing Drinking Water Samples by Method 525, Part 2: Extraction Procedure

Do Flow Rates Matter in SPE?

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!

Throughout my college career, the phrase “like dissolves like” was referred to quite frequently.  This phrase was particularly relevant when we did solubility experiments and for good reason – it’s 100% true!  Solvents tend to dissolve solutes with physical and chemical properties that are similar to theirs.  Other factors such as temperature, pressure and pH can affect the solubility of solutes as well, but let’s just keep it simple for the purposes of this discussion and keep it focused on physical and chemical properties.  Given this simplistic definition of solubility, the opposite stands true as well – solutes don’t tend to dissolve into solvents with differing physical and chemical properties.  These solvents and solutes want to stay as far from each other as is possible.

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Why It’s Easier to Succeed With Wastewater Extractions Than You Might Think

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.

Continue reading Why It’s Easier to Succeed With Wastewater Extractions Than You Might Think