All beginning scientists start realize early on that scientists can be an argumentative bunch! We love to argue! And what is the most argued over topic ever? … Glassware Cleaning! Believe it or not, just asking how clean the glassware is can spark a heated, lengthy debate among scientists! And since any modern lab isn’t using just glass anymore but a combination of stainless steel, glass, and plastic parts, don’t even get me started on asking how to clean those other parts. You could be arguing all day!
But in all seriousness, how clean does my labware need to be for my formulation toturn out right? If you are thinking along these lines, you are on the first step to coming out of the useless arguments and starting to make real progress on your project. First of all, you should always be thinking in terms of good lab practices, so any labware that contacts your formulation or associated reagents should be cleaned before each use in some fashion. We will refer this is as “General Cleaning.” Absolutely anything that you use in the lab should undergo a general cleaning prior to use.
For example, you might be used to rinsing your beakers out with ethanol or acetone prior to use, and that is likely acceptable as general cleaning. What does this general cleaning do you might ask? It mostly removes the typical dust, dirt, and debris that is found on labware that sits on a shelf for a long time. It can also remove skin oils that end up on your labware from handling it with no gloves on. What harm would all of these do? The answer is typically not much, but it can lead to some inconsistent observations and confusion. For example, did the molecule you just dissolved have a bunch of dirt specs mixed in with it or was the dirt residing on the inside of the beaker? Also, dirt, dust, and debris can cause issues with spectroscopic readings and filters, so cleanliness is always best.
But when do I need to go above and beyond general cleaning? Well that depends on your application. For critical test reagents, chromatography solvents, etc. it is definitely better to go above and beyond having them generally clean. This is because general oil, dirt/dust/debris may impact the test performance and results. For these types of reagents, it is many times best to wash them out with the main solvent that will be used. For chromatography, this is typically acetonitrile or methanol, so giving the labware a good rinse with these reagents prior to use is a good idea. Unfortunately, knowing that special cleaning is required for a particular assay tends to be tribal knowledge, so there may be a bit of asking around/trial and error that has to go on here. However, in general you should develop a basic cleaning procedure (even if it is just a solvent rinse) that allows reproducible behavior of the assay over time.
And of course, anything that is used for your main formulation applications should be exceptionally clean! This is because you want nothing present that could interfere with the chemistries behind the formulation you are making. In particular, if you are using labware that is re-useable, then you also want to make sure that any residue from previous batches is cleaned out prior to initiating a new batch. Additionally, if you are in a manufacturing environment, clogged filters, observations of dirt spekcs, etc., can be a real issue when assessing the batch for use in submission batches, animal trail batches, and human clinical trial batches.
There are a variety of approaches to cleaning out the labware depending on the exact situation (as described above) and the chemistries involved, but as a first step, you should make sure that what you are doing complies with the standard operating procedures (SOPs) of your group. Secondly, you should make sure that your practices are also approved by your Quality Assurance Group (QA). (For those of you in the academic world, your QA group is likely just your Environmental Health and Safety group.) Thirdly, you should have scientific evidence that your cleaning procedure is even doing what it is designed to do.
For example, if you have a hydrophobic compound that you are trying to clean but your cleaning is mostly water-based, I’m skeptical that you are cleaning anything. How do you go about gathering this evidence? Well, you perform cleaning studies that use a combination of experimental design and analytics to understand the effectiveness of your cleaning procedure. And that will be the focus of an upcoming post….stay tuned!