“There is a child in every one of us who is still a trick-or-treater looking for a brightly-lit front porch.” – Robert Brault
It’s Halloween! I assume you’ve carefully assembled your favorite movie character, comic book superhero or animal costume for a night of spooky fun. If you’re me, this is the day you get to wear your superhero cape out in public. As an applications chemist, I consider myself to be a bit of a superhero – but a humble one, as I wear my cape underneath my t-shirt and lab coat. I consider myself to be a superhero when I’m able to use my background and my experiences to think quickly on my feet and help troubleshoot challenges that chemists face all the time. It’s one of the best parts of my job and I’m thrilled each time I get to wear my cape – metaphorically speaking.
In my years as an applications chemist, I’ve encountered challenges that range from common and straightforward to unique and incredibly difficult to solve. In the spirit of Halloween, I am going to share a few challenges that would fall under the “Yikes” category.
Spooky Story #1: Flow Rates Gone HayWire
This spooky story occurred with an automated extraction system that suddenly started changing flow rates – and even spilled an occasional sample!
If you’re prepping your samples using disk-based solid-phase extraction (SPE), your disk holders likely have O-rings somewhere on the outside. Don’t worry, you need these O-rings to make a watertight seal between the disk holder and the extractor. What you may not realize is that these O-rings wear out over time and it can affect the flow of solution through the disk holder. If the wear on the O-ring is severe enough you could see solution flow so slowly that it builds up and spills over the edges of your disk holder. Losing your entire sample is a scary thought!
Can this be prevented? Glad you asked. A quick inspection is all it takes. Before you use your disk holders, quickly check the O-rings to look and feel for tears or flat spots. As you’re installing your disk holder, pay attention to how easy it is to connect it to your extractor. If it easily glides into place, you have O-rings that are worn out or flat and you should replace them. If the disk holder gives you resistance, your O-rings should be fine and should be maintaining the watertight seal that you need.
I would definitely keep some spare O-rings on-hand because it’s hard to predict when you’ll need to replace them. There’s nothing more frustrating than being down for a day (or two or three) because you have an O-ring that needs replacing!
Spooky Story #2: The Slow-loading Sample
This spooky story occurred with samples that were taking longer and longer to load on an automated extraction system. Given the same sample volume, same sample matrix and same extraction system, the loading time got longer and longer over time. Seems spooky, doesn’t it?
At first glance, you might look at an issue like this and think that the vacuum pump on the extractor is losing efficiency as it ages. A weaker vacuum would reduce flow rates through the SPE disk, which would lengthen the amount of time it takes to load the sample. Most commercially available vacuum pumps are pretty durable; however, so the more likely culprit is a blockage in the waste lines on your extractor. If you’re processing dirty samples (wastewater with sludge or sediment, for example), a fair number of those particles will pass through the extractor’s waste lines while the sample loads onto the disk. Eventually, these particles will build up in the waste lines and create a blockage, much like a clogged artery. This blockage will reduce the vacuum efficiency and lead to slower loading times. If the problem gets worse, the valves themselves could clog.
Can this be prevented? You bet! If you’re processing wastewaters, run warm water through your extractor at the end of each day – maybe rinse a bit longer on days when particularly challenging samples were processed.
Now, if you’re reading this and thinking “if warm water works well, I bet boiling water will work even better”, a word of caution. You’re correct in thinking that boiling water would clean the system more effectively, however, the tubing on most instruments cannot handle these types of temperatures over time. After a few rinses with boiling water, the lines can become malleable and could close or fold when placed under vacuum. It is very important to use warm (not hot) water when cleaning the instruments. Otherwise, you may be facing the scary prospect of having to replace all the tubing on your extractor!
Spooky Story #3: The Disintegrating Water Inlet Valve
This last spooky story occurred with water inlet valves (WIV) that were damaged beyond repair on an automated extraction system for processing oil and grease samples – the Biotage® Horizon 3100, to be exact. These valves are incredibly important in delivering (or stopping the delivery of) your sample onto the SPE disk so you need to take care of them to make sure you don’t lose any solution.
A lot of people realize the importance of keeping these valves clean, but most people don’t realize that the valve housing may not be resistant to the range of chemicals you may want to use for cleaning. These particular valves are made from polystyrene. Polystyrene is a very versatile polymer; however, it can be readily dissolved in many organic solvents, including acetone. As you know, acetone is frequently used as a cleaning solvent in many environmental labs, so it’s easy to spend time cleaning your laboratory equipment and accidentally damage your water inlet valve. This scenario is incredibly frightening because once the damage has been done to the valve, it cannot be fixed and will need to be replaced! Here is a full set of maintenance tips for cleaning your water inlet valves – without damaging them!
Feel free to share your spooky or scary lab stories in the comments below!