The SK5 N-Butanol kit is the official odour expert test developed by Scentroid.

The Scentroid SK5 Sensitivity Kit is designed to provide accurate N-butanol mixtures of 5 to 50 ppm from a liquid N-butanol source. The N-butanol mixture can then be used to screen panellists using the Scentroid SM100 or any other Scentroid olfactometer in accordance with standard EN13725. The mixture is accurate and repeatable thanks to the fixed volume evaporation chamber, micro-litre syringe, and pre-purged Tedlar bag.

Every odour regulation requires the screening of the panellists using diluted N-butanol samples. Until now, the only available source of a diluted N-butanol sample was to purchase pre-mixed pressurized cylinders. The cylinders were cumbersome to transport, required a special permit and storage facility, and would only be accurate in dilution if shaken or rolled just before use. The Scentroid SK5 Sensitivity kit provides an easy and reliable solution for creating exact N-butanol samples that can be used for panellist screening. Liquid N-butanol is mixed with clean odourless air at a fixed ratio using a glass micro-syringe and a stainless steel evaporation chamber.

The N-butanol kit is easy to transport and store, does not have expiration issues, and allows variable concentration.

N-Butanol Basics of Operation:

• Draw the required amount of liquid N-butanol according to the calibration chart
• Inject the N-butanol into the evaporation chamber
• Fill the evaporation chamber with odourless air from the SM100
• Close the valve and wait for 15 minutes
• Fill the 1L Tedlar bag

SK5 N-Butanol Kit

Each SK5 N-Butanol Kit contains:

• Micro-syringe
• PTFE sample bag
• Stainless steel evaporation chamber
• 1/4 fitting
• PTFE tube
• Hard carrying case

For more information on the Scentroid N-Butanol kit, click here!

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The process of analyzing the responses of odour(s) using human subjects (assessors). The responses can be used to determine the odour concentration of odour intensities or the hedonic tone of the odour. Assessors will use a series of devices known as olfactometers.

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A device that is used to determine odour concentration, odour intensity and hedonic tone. This is achieved by diluting the odour sample with odour-neutral air, which is then presented to a panel. The dilutions may be done by volume or flow-rate and are referred to as a static olfactometer or dynamic olfactometer respectively.

The device may be a mobile unit or permanently in place. It is important to note that the olfactometer should be in an odour free environment so as to not to interfere with measurements. Materials used in an olfactometer must be an odour neutral substance such as stainless steel or PTFE.

Olfactometer Range

According to the EN13725, the range of an olfactometer shall be less than 2⁷ to at least 2¹⁴, with a range of 2¹³.  The presentation of diluted air (neutral gas and odour sample) is to be at least 20l/min.

A full list of Scentroid olfactometers can be found here.

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The inability or decreased ability to perceive an odour as continued exposure to that odour increases over time. An odour may initially be strongly detectable but may diminish completely in a few minutes. Hydrogen sulphide is an example of a chemical that emits a rotten egg smell, but depending on concentration and exposure time, the rotten egg smell will no longer be perceived even though it is still present. Olfactory fatigue is not desired during olfactometry analysis or ambient odour monitoring.

During ambient odour monitoring, it is desired to provide rest periods in a neutral environment compared to the one odour is present if possible.  An example may include a vehicle, which may act as a separate environment to the one ambient odour monitoring is taking place. Perfumeries use coffee bean odour to ‘reset’ the olfactory sense.  Also, having neutral odourless air to be smelled for a few minutes may help reset the olfactory sense.

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EN13725 defines the following criteria for panellist screening:

• Have a detection threshold of n-butanol between 20ppb to 80ppb
• requires the assessor to be at least 16 years of age
• must be motivated and diligent to carry out duties
• available for the complete measurement session
• participated sufficiently to build a history of measurements
• may not eat, drink (except water), or smoke 30 min before the measurement
• not create interference from personal hygiene or perfume products
• refrain from participating in measurements if the assessor’s perception of odour is diminished (i.e. cold, allergies, etc.)
• assessors will remain in the odour room for 15min prior to beginning measurement to adapt to the room
• Panel members shall not communicate or influence one another

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A graphical tool that shows the direction and speed of wind for a specific location over a specified time period. Since wind is a transporter of odour, wind roses are an invaluable tool for determining how an odour from a source(s) could potentially be transported into a community. Wind roses can be used to help determine an effective odour monitoring plan.

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ASTM E679-04, the United States standard for the “determination of odour and taste threshold by a forced-choice ascending concentration series method of limits”, provides guidance on both olfactometry and sampling.

The ASTM E679-04 is the most commonly used standard in the USA for olfactometry, however, outside of USA standard EN13725 is more commonly accepted.

Differences between ASTM E679-04 and EN13725 is mostly on panellist screening and on minor details of olfactometry. One highly controversial difference is the presentation flow, which is set at only a minimum of 5 litres per minute in ASTM E679-04 and 20 litres per minute in EN13725. It is however technically possible to run at 20 litres per minute and still comply with the ASTM standard.

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Anosmia is the temporary or permanent complete loss of ability to perceive odour. Temporary anosmia is most commonly a result of infection or nasal blockage. Permanent loss of smell may be due to olfactory nerve damage or a brain injury. A person may have a loss of smell for one particular scent, known as specific anosmia. If an assessor is noticed to detect odours during analysis but is not detecting a specific odour this may be due to specific anosmia.

Anosmia Causes

Nasal congestion from a cold, allergies, infections, or even poor air quality can trigger a loss of smell. Other causes include:

• Polyps, small growths (not cancer-related) in the sinus blocking the nasal passage.
• Some form of injury to the nose or a form of head trauma triggering it.
• Exposure to VOCs or other harmful chemicals
• Nasal-based drug use.
• Old age. One’s sense of smell is strongest between the ages of 30 and 60, however, it begins to decline after age 60.
• Certain medical conditions, such as Alzheimer’s, Parkinson’s, MS, Vitamin deficiencies, congenital conditions, and hormonal disturbances.
• Radiation treatment of head and neck cancers.

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A federal law passed in 1970 and amended in 1974, 1977, and 1990 which forms the basis for the national air pollution control effort. Basic elements of the act include national ambient air quality standards for major air pollutants, mobile and stationary control measures, air toxics standards, acid rain control measures, and enforcement provisions.

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How Do We Smell?

Our sense of smell is governed by the olfactory bulb located in the forebrain of vertebrates. This is found high up in our noses. Small patches of tissue known as the olfactory epithelium contain millions of receptor neurons, operating as sensory signalling cells. The olfactory system is responsible for analyzing molecules located in the air and translating this data utilizing these nerve signals into the brain to be processed.

Just like taste, both senses rely on the perception of molecules. Olfaction is one of the most powerful senses, as our sense of smell allows us to detect the flavours in the food we eat. Studies have proven that olfaction is amazing enough to even trigger memories and influence our moods or behaviour! These systems are so complex, that humans are capable of detecting at least one trillion distinct scents.

The Advent of Olfactometers

In 1870 Germany, the concentration of odours was known as Olfaktometrie, which helps to quantify the human sensory experience of odours according to substance concentration, intensity, quality, and even a hedonic assessment.

Today, an olfactometer establishes a sense of odour concentration. It employs a group of human panellists, a diluted odorous mixture, and an odour-free gas N-Butanol (click here to see N-Butanol in our product lineup) to serve as a reference point. These are presented through sniffing ports to a series of panellists, who have already been perceived as odour sensitive. Odour samples are generally collected and stored in odour free sample bags that are sealed firmly to prevent degradation. Typically, any component which comes into contact with the sample must be odour free.

In comparing the smell emitted from each port, and through increasing the dilution of gas, the panellists are asked to repeat the test. This continues until the panellist responds with certainly and correctly twice in a row. It is through these responses that a single odour unit can be calculated.

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