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Glittered blue background with male housekeeper and cleaning equipmentCleanliness is safety.

Now more than ever, it is important to uphold proper sanitization and cleaning practices, or put them in place where they haven't been previously. That is all well and good, but how do you know that your disinfectants and sanitizers are doing their job? Testing the sanitizers, disinfectants, surfactants, cleansers etc. is a good way to determine their efficacy. Read on to find out more!

Understanding Sanitizer Effectiveness 

One of the key steps of guaranteeing the efficacy of your sanitation plan is choosing the correct type of sanitizer to control for the pathogens of interest based on risk-assessment—more on that later. There are three additional factors in determining the effectiveness of a sanitizer for a specific application including concentration of a sanitizer, temperature, and contact time.

Concentration of Sanitizer 

Often times, sanitizers are sold as concentrates, and thus must be diluted to a target concentration before use. Industry guidelines, federal regulations, and manufacturer’s instructions are fantastic resources for determining the target concentrations for maximum effectiveness. 

Temperature

Temperatures that are too high or too low can inhibit disinfection efficacy. It is important to consider the temperature of the environment in which the sanitizer will be applied. Most sanitizers work between the ranges of 55-120°F.

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Contact Time

Most sanitizers do not kill microorganisms instantly. They require a minimum amount of time where they need to be in contact with the surface. There are general guidelines for contact time based on sanitizer class.

 

Why is Concentration Measured? 

Sanitizers that are improperly mixed will have limited effectiveness, whereas sanitizers that are too strong can be toxic and leave unpleasant residual in products. It is therefore critical to monitor the concentration of your sanitizers to ensure that they will achieve the intended disinfection in a safe manner. Now we will take a look at the different testing methods for monitoring the concentration of these various sanitizers.

 

How are Sanitizers Measured? 

Measurement techniques depend on the active ingredients of the chemical. However, titration of chemicals to determine their concentration is a convenient way to get accurate results every time.

 

Titration (Automatic Titration)

Pros: Very accurate. Able to run multiple tests.
Cons: Can be expensive. Requires training.

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Titration is a technique in which a chemical of a known concentration, “titrant” is added to a sample an analyte of unknown concentration until a color change or other potentiometric signal occurs. The volume of titrant added is then used in a calculation to determine the concentration of the sample. In order for this to work, the titrant and the analyte must have a known, predictable reaction.  Titrations can be performed with droppers (chemical test kits), a manual burette with a stopcock, or via an automatic titration system. Manual titrations, as mentioned can be subjective and offer little in the way of record keeping. Automated systems are much more accurate, reduce inconsistencies between operators, and can export data for verification records. Manual titration setups are relatively inexpensive, whereas automatic systems are typically more of an initial investment. 

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Electrochemical Sensors

Pros: Very accurate. Can be used in many types of analyses.
Cons: Has to be used in conjunction with other instrumentation.
 

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Electrochemical sensors are devices that provide information about the composition of a solution.  They work through detecting specific analytes or properties of analytes and converting them to an electrical signal that is then translated and displayed on a monitor or meter. A lot of times, calibration with a reference material is required in order to obtain an accurate concentration. pH electrodes, conductivity sensors, dissolved oxygen, ORP (oxidation reduction potential) electrode, and ion selective electrodes are all examples of electrochemical sensors

 

The Sanitizers You Can Titrate For:

Now we'll take a closer look at individual sanitizers. While there are general guidelines provided, it is important to defer to the manufacturer’s recommendations for use. 

Iodine

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Iodine is part of the oxidizer class of sanitizers, and is commonly known as Iodophors. Iodine is used in a variety of applications. Industries such as food production, dairy, brewing, wine making, restaurants, healthcare, and aquariums. Iodine concentration when used as a sanitizer is between 12.5 ppm and 25 ppm. Iodine can target and or inhibit the growth of bacteria, yeast, mold, fungi, viruses, and protozoans. This sanitizer can be measured via multiple types of testing. These include test strips, chemical test kits, photometry (spectrophotometry), electrochemical sensors, and titration.

Pros Cons
Relatively wide pH range of efficacy 2-5 2-4X more expensive than chlorine
Effective against many different microorganisms Very temperature dependent 75-120 °F
Relatively stable in areas with residual organic debris Longer contact time required
  Can stain porous plastics

Peroxyacetic Acid (Peracetic Acid)

Peroxyacetic acid, also known as peracetic acid (POA or PAA) is an effective oxidizer that is used in a variety of applications, it is notifiable in the food industry. Food processors, breweries, wine making, restaurants, meat/seafood/poultry disinfection, egg disinfection, paper and pulp manufacturing, healthcare, and produce washing (it is even approved for production of organic produce). Between 24 to 80 ppm of PAA works great for sanitizing foods when the sanitizer is in direct contact with the item. For sanitizing equipment or surfaces, you can use a higher concentration, between 50 and 500 ppm. PAA is effective against bacteria, yeasts, fungi, and spores. Testing for PAA can be done with different methods, including test strips, photometry (spectrophotometry), electrochemical sensors, and titration.

Pros Cons
Maintains efficacy in organic soils unlike chlorine Corrosive to skin
Hard water is not a problem Breaks down quickly, so concentration should be monitored frequently
Environmentally friendly as it breaks down into vinegar and oxygen Does not leave a residual protection, like chlorine
  Expensive compared to chlorine 3-5X
  Most effective <7 pH

Bromine

Bromine is another sanitizer in the oxidizer family. It's commonly called hypobromous acid. Bromine is generally used in pools and spas, cooling towers, paper and pulp manufacturing, the meat industry, and in water treatment. The concentration of bromine needed for sanitizing varies by industry/application. 

Industry/Application Bromine Concentration (ppm)
Pools and Spas 1 - 3
Cooling Towers 2.5 - 15
Industrial Pasteurizers 1 - 9
Paper and Pulp 1 - 9
Decorative Fountains  4.5 - 9
Poultry 200 - 450
Meat 300 - 900

Bromine is able to target bacteria, fungi, algae, and slime. Testing for bromine can be done with different methods, including test strips, photometry (spectrophotometry), electrochemical sensors, and titration.

Pros Cons
Does not leave much of a residual, so does not require additional chemicals for removal Does not leave much of a residual so not a good choice for drinking water
Works across a broader range of pH than chlorine 7-8.5 - Better for alkaline waters Because it’s so reactive, more needs to be added to be effective
More stable in higher temps than chlorine - Better for hot tubs Corrosive to metals
Does not react adversely with ammonia like chlorine  

Chlorine

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Chlorine is the last sanitizer from the oxidizer family that we will talk about. It is also called hypochlorite, and chlorine dioxide. Chlorine can be used in many practical applications for households, drinking water, water treatment, food production, produce washing, meat and poultry processing, egg production, food service, pools and spas, and in aquariums. The concentration of chlorine needed for sanitizing varies by industry/application. 

Industry/Application Chlorine Concentration (ppm)
Chlorine as a Sanitizer 50 - 200 ppm
Drinking Water 1 ppm of residual chlorine
Meat and Poultry 50 - 100 ppm
Produce Washing  40 - 350 ppm (Varies)
Pools and Spas 1.5 - 3 ppm of residual chlorine

Chlorine is able to target bacteria, fungi, viruses, and mold. Testing for chlorine can be done with different methods, including test strips, chemical test kits, photometry (spectrophotometry), electrochemical sensors, and titration.

Pros Cons
Relatively inexpensive Odorous
Low contact time needed for effectiveness Reacts with organic debris, diminishing effectiveness
  Effective in very narrow pH range 6.7-7.5
  Corrosive
  Skin irritant
  Leaves residual chlorine, which can impact taste

An emergent application for chlorine as hyphochlorous acid (HOCl) is gaining ground in the dental industry. The Kois Center in Seattle, Washington and their scientific committee has recently come out with a novel approach to sanitation in a doctor's office setting. They use a small electrolysis unit to electrolyze the salts in a salt, vinegar, and distilled water solution; thus creating hypochlorous acid. This allows the offices to fog the space with effective disinfectant after a patient has left. Fogging the room sanitizes and disinfects the surfaces without dentists, hygienists, and office workers having to manually wipe down the office after every patient.

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Quaternary Ammonia

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Quaternary ammonia, also known as QUATs, is part of the surfactant family of sanitizers. When looking at labels you may also see it listed as benzalkonium chloride, benzethonium chloride, alkyl dimethyl benzyl ammonium chloride, alkyl dimethyl ethylbenzyl ammonium chloride, didecyldimethylammonium chloride, or dioctyldimethylammonium chloride. Quaternary ammonia is used in food processors, wine making, household disinfection, meat and poultry farms, food service, healthcare, and aquariums. It is able to target bacteria, fungi, viruses and molds. When using quaternary ammonia always refer to the manufacturer's specifications when determining what concentration to use. Generally, the concentration is around 200 ppm. Common testing methods to determine the concentration of quaternary ammonia are test strips, chemical test kits, photometry (spectrophotometry), titration, electrochemical sensors, and chromatography.

Pros Cons
Colorless Respiratory and skin irritant
Odorless Ineffective against spores and gram negative bacteria
Non-corrosive Sensitive to hard water
Works in a pH range of 6-10  
Can be used at high temps  

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Got Questions?

For more information regarding how Hanna Instruments can help you with measuring your sanitizers, contact us, as sales@hannainst.com or 1-800-426-6287.

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