Common Mistakes in the Lab

When working in a contract lab or any analytical testing lab, you may be prone to periods where it seems like there is never going to be a light at the end of the tunnel, as the samples just keep on coming in.

For me, I always dreaded when spring rolled around and the whole world thawed out because I knew samples would start coming in nonstop since everyone and their mother wanted to get their quarterly testing done. When faced with what seems to be such an insurmountable workload some of your normal good lab practices might take a hit if you are rushing to extract before a sample’s hold time expires. One such good lab practice is properly cleaning the glassware or anything else that might come in contact with your samples.

Properly cleaned equipment in the lab is very important as it may be a source of contamination or could cause unwanted interactions. Some of the more well-known contaminants that love to stick around on surfaces include phthalates, such as diethyl phthalate or bis(2-ethylhexyl)phthalate, and polychlorinated biphenyls (PCBs) which love to stick around the environment in general. These compounds can derail your entire workflow such as ruining your QC samples or even ruining an entire extraction batch of 20 samples since that PCB pattern was concentrated enough that it helped contaminate everything. I can still remember the time when that entire afternoon of work going to waste because of that, not to mention the amount of capillary column I had to trim from my GC to get rid of the aftermath.

So how should we ensure that all of our laboratory equipment is properly cleaned to avoid these problems? From my experience, this is the most foolproof method to properly cleaning your lab equipment. Rinse anything that will come in contact with your standards or sample extracts three times with whatever solvent they are in both before and after use. These rinses should be done immediately after use, otherwise, you might forget because not all samples will leave a brown or yellow stain on your glassware. Anything that will come in contact with a sample should first be washed using a non-abrasive cleaning solution, otherwise scoring might form in glassware that can lead to even better hiding places for those contaminants. Also, make sure the scrub brushes you are using are in good condition as they can also lead to the same scoring in the glassware. Once that is complete, they should be rinsed with tap water, then deionized (DI) water to ensure that the cleaning product is fully rinsed off. If you need that equipment fast, you can bake your glassware in an oven to further remove any contaminants and speed up the drying time. If not, they can be left upside down to dry normally.

Now I know it may be hard to find the time to do all of this when you’re staring down a list of 80+ samples to extract in a week, but otherwise, you are leaving yourself open to heartbreak when you have to re-extract an entire batch of samples because you failed your blank or control spike sample due to contamination. All it takes is a few extra minutes to do it right so that you can avoid spending a few extra hours down the road if you do it wrong.  

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