Comparison of Single-Use Funnels vs. Reusable Funnels for the Membrane Filtration Method in QC Microbiology

Reusable and single-use funnels are both viable options to perform membrane filtration during quality control to ensure the microbiological safety of final products. Single-use funnels are seen as more convenient, accurate, and safe in bioburden testing, while reusable ones are cheaper and less wasteful. However, the choice of funnel depends on a wide range of criteria, accuracy and results repeatability, total costs and waste, convenience and flexibility, and staff safety.

• Costs and Waste: Reusable Vs. Single-Use Funnels
• Operating Time: Funnel Set Up
• Accuracy and Repeatability of Bioburden Testing Results
• Convenience and Flexibility in Bioburden Testing
• Operator Safety During Bioburden Testing
• Conclusion: Advantage of Single-Use Funnel
• EZ-Fit^® Filtration Units
• Related Products

COSTS AND WASTE: REUSABLE VS. SINGLE-USE FUNNELS

The operational efficiency that single-use funnels provide is one factor that offsets the extra spending on the products themselves. Another factor is reduced spending in other areas.

Facilities that use reusable funnels need autoclaves and other pieces of cleaning and sterilization equipment, so in addition to the capital investment they also need to spend more on the human resources and electricity required. A boiling water bath can cost as much as EUR 1500 and EUR 20 for a liter of the alcohol used in the flaming process to ensure sterility. Putting reusable funnels through a 324-liter autoclave consumes around 18kW of electricity, adding further to the costs.

These factors also offset the perceived environmental benefits of reusable funnels. While single-use funnels may appear wasteful at first glance, they are made up of recyclable materials and have no hidden environmental impacts. Manufacturers often provide information on how to recycle single-use products for sustainable waste management. Reusable funnels, in contrast, are associated with a range of hidden impacts, including the amount of energy, water, and detergent needed to clean them.

Flyer: Waste management with single-use filtration funnels

OPERATING TIME: funnel set up

Single-use filtration units can save precious time, taking only a second to attach a funnel to a plate during filtration set-up.

Reusable funnels, on the other hand, require several steps: flaming the manifold head as well as the funnel’s base and inside, cooling with sterile water, placing the filter on the manifold head, and installing the manifold on the filter.

ACCURACY AND REPEATABILITY OF BIOBURDEN TEST RESULTS

Every test performed with single-use funnels for membrane filtration starts with a sterile product that will not introduce foreign microorganisms therefore the results generated will be consistent each time. The same cannot be said of reusable funnels:

• The cleaning process introduces the risk that soap residues will interfere with samples and results
• Nitrate-based detergents pose a particular problem as their residues hinder microbial growth
• There is also a possibility of a sterilization process failure and creating a cross-contamination risk
• Wear and tear on funnels can also lead to sample bypass

While reusable funnels can deliver accurate, repeatable results, these risks have notable but hard-to-quantify implications that make single-use products an attractive option for bioburden testing.

CONVENIENCE AND FLEXIBILITY IN BIOBURDEN TESTING

The convenience of single-use funnels is a big part of their appeal. One of the factors that makes a single-use funnel more convenient is its ease of use. They make membrane filtration and membrane transfer to agar plates much easier to perform. The single-use workflow is free from the risk of tearing and rippling of membrane filters that affect users of reusable funnels.

Another key factor is that single-use funnels eliminate cleaning and sterilization steps. A facility that normally analyzes 10 samples a day may have 12 reusable funnels. On normal days, the facility might have access to a clean and sterilized funnel at any time. However, when they must process 20 samples by a tight deadline, not enough sterilized funnels would be available. This would inevitably delay the sample analysis workflow.

The solution would be to use single-use funnels that are always ready to use. With single-use funnels, facilities can quickly scale up their capacity to meet the demands, allowing them to spend more time analyzing samples and less time waiting for clean equipment.

OPERATOR SAFETY DURING BIOBURDEN TESTING

Cleaning and sterilization pose risks to operators, especially during the flaming process. Flaming as such doesn’t cause safety hazards but the combination of flames and flammable fumes involved in the process has caused multiple safety issues.

The blistering of the skin is the most common occurrence. This happens when the operator holds the stainless steel funnel against the flame in order to sterilize it but does not realize the funnel has heated rapidly. Some operators have even burnt their arms during flaming. Flaming can also pose a fire hazard to the whole laboratory and its staff.

Single-use funnels for membrane filtration during bioburden testing are free from these risks. Operators can simply attach a funnel to a plate and dispose it after use, freeing it from the dangers associated with flaming and other ways of sterilizing reusable equipment. As a result, single-use funnels create a safer working environment.

Flyer: Improved safety of your membrane filtration workflow with single-use funnels

Conclusion: SIGNIFICANCE of single-use funnel

The accuracy, convenience, and safety of single-use funnels make these products well-suited to the needs of quality control laboratories in pharmaceutical manufacturing units. Easy access to single-use funnels makes it convenient for sample filtration, delivering accurate and repeatable results with maximized safety.

The benefits can be achieved without incurring many upfront and running costs and without the environmental impacts associated with reusable funnels. This makes single-use products an attractive alternative for even the most cost and waste-conscious laboratories.

Watch Webinar: Impacts of the membrane filtration funnel on your workflow

EZ-FIT^® FILTRATION UNITS

Bioburden testing won’t be a burden when you use EZ-Fit^® Filtration Units. This sterilized, ready-to-use disposable filtration device for microbial membrane filtration, can streamline your workflow, save time, and give you highly reliable microbial enumeration results. Simply, filter your liquid sample and transfer the membrane onto an agar plate or add liquid media from an ampoule to culture the captured organisms.

Watch the video to learn the amazing features of the EZ-Fit^® filtration units that make it a reliable microbial enumeration device.

EZ-Fit^® pink units come with a wide range of membrane pore sizes – from 0.22 to 0.8 μm, for maximum versatility to suit all application needs. The new patented drain design speeds up the filtration time of turbid and hard-to-filter matrices.

EZ-Fit^® blue units give extra flexibility: After filtration, either transfer the membrane to an agar plate or add liquid media and convert the device into a petri dish.