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Hidden costs of blending 70% alcohol for disinfection


Georgina Froud
Communications Manager
Shield Medicare
E:[email protected]

When manufacturing your own 70% ­alcohol, it is important to consider five main areas that are affected:

  • Production efficiencies – the cost of downtime, dedicated staff, or staff taken away from their core activity to make alcohol.
  • Wastage and disposal costs of diluted alcohol and raw materials.
  • Validation and monitoring – this is time-consuming and difficult (and you could fail an audit if not done correctly).
  • Staff time – both production staff and quality control (QC).
  • Health and safety risks of handling and storing bulk concentrate.

What is the real cost per litre when you make it yourself?
IPA (isopropanol) or denatured ethanol should normally be used at 70% concentration with water of suitable quality to be most effective for disinfection. For Grade A and B areas, this can be achieved by purchasing 95–99% alcohol and diluting it with Water for Injection (WFI). When calculating the cost per litre of the alcohol, most organisations only take into account the cost of the purchased alcohol and we often hear people say: “It is so much cheaper to make it ourselves.” However, there are many other potentially hidden costs to add (see Box 1).


Raw materials
WFI can be expensive, so the cost of raw materials is usually much higher than estimated. To obtain the correct dilution, a minimum quantity of 70% alcohol needs to be produced, and this is often more than would be used in one disinfection session. So either there is a lot of wastage of alcohol and WFI, and the subsequent cost of waste disposal, or the 70% alcohol has to be stored longer, which requires validation and leads to an increased risk of contamination from spores. There is also the cost of storage space for the raw materials and empty bottles, and storage conditions need to be carefully monitored. In some countries the amount of flammable liquids that can be stored is very small unless specific storage conditions are provided.

Either dedicated staff are employed to make the alcohol or technicians need to be taken from production to carry out this task. In some cases, production stops completely while technicians make the next batch of alcohol. Consideration needs to be given to the cost of staff time to: assemble and prepare equipment; test to confirm correct dilution and blending; record data and ensure good manufacturing practice (GMP) compliance. There is always a risk of incorrect dilution when alcohol and water are blended due to the immiscibility of the fluids. The top and bottom of every batch should be tested to ensure homogenous mixing; otherwise, bottles filled from the top of the container may contain 90% alcohol and bottles from the bottom 20% alcohol. This is even more crucial when the blending has been carried out manually.

GMP states that all disinfectants used in Grade A and B areas should be sterile prior to use. However, alcohol cannot be autoclaved due to its low flash point, so unless you can send your alcohol out to an irradiation plant (is this really easier than buying sterile alcohol?) then the only other option to meet GMP requirements is to filter the alcohol into sterile bottles. Even if you are only sterilising the bottles, GMP states that all sterilisation processes should be validated. Loading patterns need to be established, and the validity of the process should be verified at regular intervals.

Consideration should be given to the initial bioburden on the bottles and, therefore, biological indicators (another cost) should be used as an additional monitoring device and records should be available for every batch. Overall, a validated sterilisation process is time-consuming and expensive.

This is an important part of the process that removes viable and nonviable contamination from the liquid either to reduce the initial bioburden if the alcohol is being terminal sterilised, or as part of the sterilisation process if this is not the case. There should not be a time delay between the product being filtered and sterilisation. Staff will need to: sterilise filters; integrity test filters and record validation data. The integrity of a sterilised filter should be verified before use and confirmed immediately after use. The same filter cannot be used for more than one working day unless it has been validated.

Whether using trigger sprays, squeeze bottles or capped bottles, this is another significant part of the preparation. As well as storage and preparation areas, consider the cost of staff time to sterilise bottles and carry out validation of the sterilisation, as well as the cost of staff time to fill the bottles, ideally aseptically. Validation of sterility by QC will also be required.

Validation and monitoring
All the data needs to be recorded for every batch at each step of the production process, creating a full paper trail to meet auditing requirements. What are the consequences for you if this part of the procedure gets missed or forgotten? This element alone takes considerable time for QC personnel and their time is not cheap.

Meeting GMP guidelines
GMP states that: “Disinfectants and detergents should be monitored for microbial contamination; dilutions should be kept in previously cleaned containers and should only be stored for defined periods unless sterilised.” Unless sterile initially and protected from contamination during use, alcohol has a limited shelf-life and much of the batch will therefore be wasted. When in use, the alcohol can become contaminated after only a few hours, unless the bottle incorporates a closed trigger spray system, so again there is significant wastage.

What cost do you place on increased risk of contamination?
When you make 70% alcohol yourself there are many steps to be undertaken, and if correct procedures are not in place then errors or contamination could easily occur. This could be incorrect dilution or blending, which makes the alcohol less effective as a disinfectant, or it could be an error as basic as filtering sterile alcohol into a nonsterile bottle that will give you a disinfectant that may be contaminated with bacterial spores. These spores could then be spread around the cleanroom.


When you purchase sterile alcohols from a reputable supplier, the sterility of the product is guaranteed, as each packaged bottle is gamma-irradiated. Every step of the production process is validated and supported with technical information, and batch certificates are supplied. The product has a two-year shelf-life, enabling bulk purchase and minimising batch recording. The bottles are double-bagged to enable easy transfer into the cleanroom.

Why not make your job easier?
70% IPA and denatured ethanol blended with either WFI or Deionised Water are available sterile and double-bagged in various formats especially for use in cleanrooms, with a hands-free dispenser option. You could give yourself one less thing to worry about and free up time and staff to improve production efficiencies.

There can be many benefits from purchasing sterile alcohol from a reputable supplier, not least of which is the minimised contamination risk. Other benefits include:

  • No dilution errors.
  • No storage of opened bulk concentrate.
  • No cost for bulk containers.
  • No wastage of unused product due to long shelf-life.
  • Simplified batch recording.
  • Minimised batch validation.
  • GMP compliance.
  • No resterilisation and validation costs.
  • No filtration costs, sterilisation of filters or replacement filters.
  • Supplied with full certification.
  • Saves production and QC staff time.
  • Minimises health and safety concerns (eg, storing bulk containers of flammable liquid and injuries sustained from moving the heavy containers).

Ready-to-use sterile alcohol offers massive benefits compared with manufacturing your own alcohol:

  • Save time by cutting out the need for preparation, validation and monitoring.
  • Save money through reduced wastage, removing the need for dedicated preparation and storage areas and eliminating staff time spent on manufacturing and validating the alcohol.
  • Reduce contamination risks by using an alcohol that is cleanroom manufactured, fully validated, guaranteed sterile and spore-free.

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