If COVID-19 taught us anything, it’s the importance of cleaning and disinfecting. From our hands to commonly used spaces, disinfection is vital to stop the spread of contamination. Of course, this is a lesson laboratory personnel were already all too familiar with.
In the lab, contamination comes in all shapes and sizes—but none with positive results. In fact, one of the most common tasks in a laboratory—cleaning and disinfecting glassware—is prone to contamination, which can cause invalid analytical results. Effective laboratory processes must include labware free of soil, grease or other residual impurities that can contaminate active processes or samples, and lead to false outcomes.
Let’s take a look at a few challenges researchers often encounter when it comes to washing their glassware, and the best ways to rectify the situation to ensure safe, reliable and reproducible experimental results.
Challenge 1: Oddly shaped glassware
Solution: Awkwardly shaped glassware is one of the most common problems researchers encounter. Graduated cylinders need to be loaded at an angle so the base does not trap a large amount of dirty wash water and contaminate the rinse. If there is no option to tilt the cylinders to promote drainage, then an extra rinse may allow sufficient exchange of water by stopping at the end of the wash cycle.1
Meanwhile, pipettes require special flow-through fittings and racks to clean in a washer. Narrow neck flasks are best cleaned using special spray spindles that fit up inside the flasks to assure that cleaning and rinsing solution gets to the inside. For difficult, irregularly shaped glassware you may be able to get custom racks that promote proper cleaning and draining from the washer manufacturer.1
Challenge 2: Difficult-to-remove materials
Solution: Waxy, sticky cannabis and hemp residue, in addition to other botanical resins, are among the most difficult to remove, clean and disinfect. Most of the time, caustic cleaning solutions and acid rinsing are viable options for cleaning cannabis residues in glassware. Other times, however, the residues can be quite gummy and viscous. In these cases, it is important to have specialized features in a lab washer to allow programming and extra dispensing. Adding an emulsifier into the wash cycle and heating to a higher wash temperature ensures that gummy, tenacious residue is removed.
Challenge 3: Reoccurring water spots on glassware
Solution: Acid rinsing is a periodic (monthly or quarterly) empty acid-wash cycle to remove scale buildup that can clog nozzles and deposit white calcium scale. Sometimes insoluble metal hydroxides form, amphoteric proteins deposit, and alkaline insoluble residues—such as certain polymers—fail to be removed during alkaline cleaning. To remove these residues, an acid-rinse step is required. Many rinse aids are cationic positively charged compounds that are attracted to surfaces that repel the water. This can leave deposits of water-repelling rinse aid on the surface. To avoid water spots when washing labware, it is better to use multiple deionized water rinses and good loading procedures to avoid trapping and carrying over wash water with residue load.1
If only tap water is available, it may be better to set the washer to air dry and open the washer immediately after the first rinse. Then manually rinse in deionized water before proceeding to an air dry or a heated drying cycle.1
Challenge 4: Validation and residue detection method
Solution: There are GMP regulations surrounding washer/dryer design and construction; however, some areas are left open for interpretation. According to Alconox, Inc., a manufacturer of laboratory detergents, a documentation package is needed to complete the validation and qualify the cleaning system. At a minimum, the package should contain the following components: users’ manual; maintenance manual; instrument list; electrical diagram; piping and instrumentation diagram; spare parts list; exploded view; welding report and welder certificate; source codes in both printed and digital form; passivation report; as-built drawings; and Q/OQ documentation.
Be sure to also consider the requirements of the College of American Pathology for residue detection method, and state and NELAC standards for certificates of analysis and inhibitory residue test reports. If your industry requires validating your residue detection method, be sure to chose a supplier that supports regulatory-compliant cleaning validations.1 This includes being able to provide lot number traceability of all cleaners and ingredients, cleaner toxicity and reactivity/degradation information, shelf-life testing, residue sampling, detection methods and written cleaning procedures. Each cleaning product from Alconox, for example, is tested by lot number, with Certificates of Analysis available to end users with quality control or regulatory-compliance requirements.
Challenge 5: Company sustainability goals
Solution: Between energy and water, laboratories hog more than their fair share of resource consumption. For this reason, many research companies have launched sustainability initiatives; and glassware washers play a vital role in the Green Lab of the Future. When deciding which glassware washer to purchase for your lab, look for options that show a commitment to green technology. My Green Lab, a non-profit organization dedicated to creating a culture of sustainability in science, keeps a searchable database of products and how they “rate” in sustainability-related categories—think nutrition label, but green.
References
1. Guidance for Labware Washer Cleaning [Better, Safer Science Through Proper Detergent Selection and Cleaning]. Alconox, Inc. https://www.alconox.com/wp-content/uploads/2020/07/Labware-Washer-Guide.pdf