Anotec Research Into The Chemistry Of Odours When Developing Detergents

2008

Victoria Zavras

Odour research in the development of detergents and cleaning agents

It is not enough to simply formulate according to what is available on the market today. All Anotec formulations are based on extensive research, thorough independent testing and, of course, the response from the client. Of utmost importance is the understanding of the application of the product and its suitability in any given area (e.g. hospital, sewage treatment plants etc.). This booklet will briefly outline the key areas of Anotec research that is instrumental in our supplying you the best product available today. Anotec is one of a few commercial companies in the world to formulate and develop cleaning and air quality products using state-of-the-art technology enabling Anotec to scientifically prove that their products work!

Anotec Pty Ltd 30-32 Chegwyn St Botany NSW 2019 Tel: 02 9700 1222 Fax: 02 9700 1771 Email: [email protected] Website: www.anotec.com.au

ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS At Anotec Pty Ltd we are committed to maintaining and constantly improving the standards of excellence that we have achieved over the past ten years. Standards that have brought us distinction as a specialty range chemical formulator and manufacturer of effective odour control, sanitation and cleaning products. Anotec Pty Ltd is proud to have adopted the BATNEEC (Best Available Technology Not Entailing Excessive Costs) Policy which is applicable for all industry types including the commercial and domestic sector. We are dedicated to supplying our customers worldwide with quality products, competitive prices, total technical support and continuous research & development ensuring that we and by extension by you, lead the industry with unique products and innovative solutions. Anotec ® additionally promotes responsible environmental housekeeping through careful managing of our manufacturing formulas, practices and facilities. It is not enough to simply formulate according to what is available on the market today. All Anotec formulations are based on extensive research, thorough independent testing and, of course, the response from the client. Of utmost importance is the understanding of the application of the product and its suitability in any given area (e.g. hospital, sewage treatment plants etc.). This booklet will briefly outline the key areas of Anotec research that is instrumental in our supplying you the best product available today. Anotec is one of a few commercial companies in the world to formulate and develop cleaning and air quality products using state-of-the-art technology enabling Anotec to scientifically prove that their products work! Odours From time to time people detect odours from sources such as industries and waste dumps. Should they be concerned every time their noses pick up a scent? The answer to this question is "probably not". Most of the chemicals causing odours will not harm you even though you can smell them. Some chemicals have low "odour thresholds", meaning that your nose can detect their scent at levels much lower than the levels that can cause adverse health effects. One's ability to sense a particular odour also depends on who you are; not everyone's nose is sensitive to certain odours. Scientists estimate that most people (about ninety six percent of the population) have a normal sense of smell, but some are insensitive or supersensitive to smell.

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS Also, people who are exposed to a certain odour frequently may become extra sensitive, or insensitive, to it. Long-term residents of an area where there really are odours may be surprised when visitors from other areas smell odours that they themselves have become insensitive or accustomed to. And certain chemicals have odours that only a few people can detect. The acceptable level to which the general population may be exposed should be much lower than acceptable level for workers, of course, but since there are no established equivalent limits for public exposure we use worker limits for comparison. The abbreviation "ppm", used when talking about levels of chemicals present in air or water, stands for "parts per million", a way of measuring tiny concentrations. One part per million of a chemical can mean for example, that there is one molecule of chemical per one million molecules of air. Another way to think of 1 ppm is to imagine one drop of sweetener in 178 cups of coffee - enough coffee for one cup a day for about half a year. Except for benzene, the list herein shows that what you can smell easily will not necessarily hurt you. Your nose will pick up a scent at low concentrations, but the chemical will not start to affect your health until the amount present is much higher. In some cases, what you cannot smell may hurt you with little warning. Consider carbon monoxide, a common deadly gas with no odour that can suffocate unwitting victims. Another common source of undetectable gas comes from burning some popular non-stick (Teflon ®) kitchen pots or pans with no food or liquid in them. Undetected gas given off by such pots will kill pet birds within a few hours. Obviously, as the table shows, odours can be an important early warning that a potentially hazardous gas is present. The table shows how a chemical's odour is linked to its potential to affect health. The second column tells what a chemical smells like at its lowest detectable level. The third column describes the chemical's odour threshold, above which most people can smell or recognise the odour. The fourth column is the Permissible Exposure Level (PEL), a safe level set by OSHA to protect workers exposed to the chemical on a daily basis.

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS CHEMICAL

Cresol Naphthalene Phenol Chlorine Hydrogen sulfide Pyridine Toluene Ammonia Xylene Benzene Ethyl alcohol

CHRACTERISTIC ODOUR Creosote Mothballs Medicinal / acid Bleach Rotten eggs (sulfur) Burnt / pungent Sweet (like glue) Pungent Sweet Aromatic Sweet / alcohol

0.0006 ppm 0.008 ppm 0.06 ppm 0.08 ppm 0.094 ppm

OSHA PERMISSIBLE EXPOSURE LEVEL 5 ppm 10 ppm 5 ppm 1 ppm 20 ppm

0.66-0.74 ppm 1.6 ppm 17 ppm 20 ppm 61 ppm 180 ppm

5 ppm 100 ppm 50 ppm 100 ppm 1 ppm 1000ppm

ODOUR THRESHOLD

CHEMORECEPTION Our senses provide us with information about our environment. These senses respond to a variety of stimuli. The pressure of physical contact with an object stimulates the sense of touch. Hearing responds to rapid fluctuations in air pressure. Sight is produced by electromagnetic radiation falling on the retina of our eyes. Two of our senses respond to the chemical nature of our surroundings: taste and smell. It is because they depend on chemical interactions that these two senses are called chemoreception. Taste is called contact chemoreception because to experience the flavour of something we must come in contact with it. Smell is remote chemoreception for we can sense the odour of an object at a distance. The sense of smell (olfaction) is both a very simple and a very complex sense. It is simple because relatively few cells are involved in detecting odours. In humans, the olfactory sensors are located at the top of the nasal passages, just below and between the eyes. Without getting into too much detail, the mechanism by which the odour receptor cells interact with odourcausing molecules is still unknown, but studies of odours and the structure of the odour-causing molecules has revealed some correlation. With each breath we take, air is swept over the olfactory senses. These senses are covered with a coating of mucus. Molecules from the air dissolve in this mucous and interact with filaments of the olfactory cells. Because odours are sensed only when gaseous molecules dissolve, all odour-causing materials must produce vapours. Materials that release virtually no vapour, such as ionic salts, are odourless. Only volatile materials that are soluble in the mucous and that interact with the olfactory cells produce odours. Odours are of a significant commercial concern (think about the food and beauty industries), the study of odours by Anotec has been quite extensive.

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS Odours have been classified by a variety of methods, depending on the application. In the food industry, the odours of chemical compounds are categorised by the identity of the edible material of which they are suggestive. This produces odour classes such as caramel, honey, vanilla, citrus, and butter. In the beauty industry, odours are more likely classified by floral and herbal groupings, such as jasmine, rose, balsam or pine. For purposes of our investigation of how odours are perceived, the classification is more precise. The scientific classification of odours attempts to find so-called primary odours, in analogy to the primary colours of vision. To do this, scientists have exploited a common defect in the human sense of smell. In any large group of people, there are some who cannot detect the odour of a particular substance or group of substances. These people are "anosmic" toward a particular odour. This is the olfactory counterpart to colour blindness. Just as there are different types of colour blindness, there are a variety of anosmias. Scientists investigate which odiferous substances certain anosmic people cannot detect. These substances are then classified into a single "primary" odour category. Originally, eight primary odour categories had been identified: camphorous, fishy, malty, minty, musky, spermous, sweaty, and urinous. Now the list has grown considerably to include: alliaceous, animal, balsamic, chemical, citrus, coffee, earthy, ethereal, fatty, floral, fruity, green, herbaceous, meaty, medicinal, minty, mossy, musty, nutty, pepper, smoky, soapy, spicy, sulfurous, vegetable, waxy, wine-like and woody. The odours of the majority of substances are produced by a combination of these primary odours, just as colours are produced by a combination of primary colour responses. Furthermore, many of the odours we easily recognise are produced by the combination of many compounds. For example, over 80 odoriferous compounds have been identified in the jasmine blossoms. A comparison of the structures of the molecules of materials in each category of the primary odour classifications reveals similarities among the molecules in some types. For example, substances having a fishy odour are generally amines containing a nitrogen atom bonded to three other atoms and having a non-bonding pair of electrons. Examples include dimethylamine, H3C-NHCH3, and ethylamine, H2N-CH2CH3. The molecular structures of several minty materials also reveal some similarity.

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS Fig. 1

Anethole

Benzaldehyde

cinnamaldehyde

methyl salicylate

However, very subtle differences in structure can produce different odours. For example, looking at Fig. 2, the difference between R-carvone and Scarvone is that in R-carvone, the hydrogen near the asterix is below the double bonded carbon, but in S-carvone, the H is above the C. In all other respects the structures are identical. Although both are in the minty category, the odours are distinct. Fig. 2

R-carvone

S-carvone

In some of the categories of odours, especially the musky category, the range of molecular structures is very broad. Certain structural features of a molecule can be associated with a particular type of odour, although that odour may not be one of the primaries. A good example of such a feature is the mercapto group, -S-H. Most volatile materials that contain this group have strong odours. The simplest such molecule is H-S-H, hydrogen sulfide. This gas produces the characteristic odour of rotten eggs. Allyl mercaptan, H2C=CH-CH2-S-H, produces the characteristic odour of garlic. Tertiary-butyl mercaptan, (CH3)3C-SH, is one of the materials (along with dimethyl sulfide, CH3-S-CH3) added to natural gas to produce the characteristic odour that signals a gas leak. Overseas, some gas companies distribute cards with micro-encapsulated odourant to teach customers this characteristic odour; once smelled, never forgotten. An

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS indication of the intensity of the odour of t-butyl mercaptan is that only 2.5 grams of it are required to produce 1 million of these cards! Several theories of how molecules interact with the olfactory cells are currently under investigation. One proposes that odourant molecules vibrate at characteristic frequencies, and that olfactory cells contain molecules that vibrate at similar frequencies. When odourant molecules get close to the olfactory molecules in cells, the odourant molecules stimulate the olfactory molecules to vibrate at the characteristic frequency, thereby generating a response. Another theory suggest that odourant molecules penetrate the wall of the olfactory cells, disturbing the electrolyte balance between the exterior and interior of the cell and generating nerve pulse. Perhaps the most widely accepted theory emphasises the importance of size, shape and electronic arrangement of the odourant molecule. According to this theory, the olfactory cell responds to the size, shape and electronic arrangement of the odourant molecule. Whether this response occurs at sites specific to certain combinations of size and shape, or whether it is a generalised reaction is still a matter of discussion. However, it is known that olfactory cells are not specific to a particular primary odour, unlike cells of the retina that respond to only one of the primary colours. A single olfactory cell responds to molecules in several of the primary odour categories. Using most of the above as our basis for the development of quality odour control, Anotec Pty Limited successfully supply the Anotec range of Odour Control products worldwide for industrial, commercial and domestic applications. The latter includes service utilities, agriculture, hospitality, medical and aged care, childcare facilities - just to name a few.

CLEANERS & DISINFECTANTS KEY CHARACTERISTICS OF THE PRINCIPAL HARD SURFACE DISINFECTANTS Since Lister, a biochemist/microbiologist showed in 1867 that phenol (carbolic acid) would kill microorganisms, many chemicals have been tested for this purpose, and a few have proved to be effective. These chemicals can be classified relative to our principal area of interest, that is, hard surface disinfection. The following are undoubtedly the most important. 1. Quaternary ammonium compounds 2. Phenolic compounds 3. Iodophors 4. Pine oil

The following discussion will examine the relative advantages of each of these chemicals within the context of their use when formulated with a detergent

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS material to form a hard surface detergent/disinfectant. To do this, however, it is necessary first to consider what we mean by a good disinfectant. The first criterion obviously is that it kills microorganisms of all kinds, particularly the pathogens, although destruction of others, which are considered harmless to humans and animals, is sometimes also important. Many non-pathogens attack organic matter, producing chemicals that may be highly odorous, corrosive or staining. Elimination of such organisms is certainly a plus factor to be desired from any product. Germicidal products that kill a wide range of microorganisms are said to be broad spectrum. It must be emphasised that hard surface disinfection can best be achieved when it is accomplished as part of a one step operation involving a detergent. If a germicidal agent is applied to a dirty surface, it will kill those organisms which it contacts, but most of them will probably be surrounded by soil and be unaffected by the chemical. Thus it is important that the disinfectant chemical be compatible with the detergent system with which it is to be combined. Of course, one could always do the job in two steps - first clean the area, then treat it with a disinfectant. This procedure will be highly effective in terms of reducing or eliminating the bacterial load on the surface but it has two major drawbacks. Labour cost is approximately 95% of the cost of maintenance, and by requiring that an area be treated twice - first for detergence, then for disinfection - labour cost is doubled. This is an extremely important consideration, and it explains the almost complete disappearance of single service disinfectant products. Most products today combine detergence with disinfectants so that the job can be done in one operation. Actually, the matter of labour cost is rather minor when compared to the other drawback. A two step operation of cleaning followed by disinfection greatly increases the possibility and dangers of cross contamination. Consider what happens during the cleaning operation. The housekeeper or cleaner applies a detergent solution on the area to be cleaned, then picks it up with a mop or wet vacuum, and finally disposes of the solution containing the picked up soil. The overall effect of this activity has been to concentrate into the dirty water all the microorganisms that have been picked up in the cleaning process. Unless handled with great care, this contaminated solution can contribute to the spread of contamination. Not only is the combination product more cost effective but it will provide far better overall result.

Most detergent/disinfectant products are produced as liquid concentrates that must be diluted with water before use. In handling these products, either as the concentrates or the use dilutions, it is difficult to avoid having them come into contact with the skin. In an extreme case, an accident may occur in which some of the product may be splashed into the face, perhaps into the eyes. An important requirement, therefore, for this type of product is safety -freedom from irritation if product gets on the skin or in the eyes and freedom from toxicity if it is ingested.

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS

In the evolution of environmental sanitation, (hard surface cleaning) the removal of unwanted physical soil was followed by sanitising or disinfection for the destruction and removal of microorganisms. Eventually, these two functions were combined so that only one product was needed. However, it was later recognised that there is a third important dimension to environmental sanitation - odour control. Unpleasant odours are an unfortunate fact in most hospitals, nursing homes, mental institutions, schools and many other facilities. Counteracting these odours required incorporating an odour control system into the detergent/disinfectant product. To this end, it is advantageous to begin with a detergent/disinfectant that has little or no odour. Chemicals like phenol are highly odorous and they are almost impossible to effectively mask or neutralise. Consequently, detergent/disinfectant products which incorporate phenol derivatives have that tell tale "Hospital odour". Quaternaries, on the other hand, have a very low almost nondescript odour and can thus be readily combined with odour control ingredients.

An important factor in detergence is pH which is a measure of acidity or alkalinity. A product with a pH of 7 is neither acid nor alkaline. It is neutral. Below 7, the product is acid; above 7, it is alkaline. As the pH of a detergent solution rises, i.e., becomes more alkaline, the cleaning efficiency of the product increases. There are limits to this, of course, since too high a pH will frequently result in deleterious effects on the surface being cleaned. In general, a pH no higher than 10.5 is acceptable. This does not mean that a product is safe at 10.5 and harmful at 10.6. There is a range in which harmful activity will begin, and the breadth of this range is dependent on the other ingredients in the formulation. As a general rule, the use of a pH of 10 gives us a cut-off point with a built-in measure of safety. Another highly important factor is the use of inorganic builders and chelating agents to improve detergence. These agents operate best in an acid medium. Thus, it is apparent that disinfectant chemicals intended for use in a combination product should have good activity at an alkaline pH up to 10.

One final factor requires consideration. The activity of all disinfectant chemicals is affected adversely by organic matter. The degree to which this occurs varies with the particular chemical and probably with the type of organic soil present. Therefore it is advantageous to choose as the germicidal component of the product one which is least affected by organic matter. Having examined the major characteristics to be evaluated in electing the proper germicidal chemical for a detergent/disinfectant product, we can now evaluate the most important available biocidal chemicals. A recap of these characteristics gives us the following:

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS

1. Broad spectrum activity 2. Compatibility with effective detergents 3. Low oral toxicity and skin irritation 4. Freedom from odour 5. High activity at same pH as the detergent component 6. Retention of activity in presence of organic matter

QUATERNARY AMMONIUM COMPOUNDS 1. Spectrum of Activity Hundreds of different quaternaries have been prepared and tested. Some are good clothes softeners. Others are effective antistatic agents for certain application. A relatively small number have been found to be highly effective germicidal agents. Of this last group, an even smaller number are bactericidal and fungicidal against an extremely wide range of microorganisms. This activity covers the gram positive and gram-negative bacteria, fungi and viruses. We can say, then, that selection of the proper quaternary will give a product with a wide spectrum of activity. 2. Detergent Compatibility. The most effective of the products available for uses as hard surface detergents are the synthetic nonionics. Properly formulated, the quats are compatible with these materials. 3. Low Oral Toxicity and Skin Irritation. All disinfectant chemicals have some degree of toxicity and irritation in concentrated solution. Many of them carry these properties over into the low concentrations required for effective disinfection. This is not true of the quats. Use concentrations of 400-500 ppm of quaternary are normally used for disinfection. At these concentrations, the product is not irritating and has an extremely low order of oral toxicity. 4. Freedom From Odour Quaternary ammonium chlorides are odourless. 5. High Activity at Alkaline pH. The germicidal activity of quats increases as the pH increases. This means that optimum germicidal and detergent activity can be obtained from a quaternary/nonionic combination, since both shows increasing activity with increasing pH. 6. Retention of Activity of Organic Matter All disinfectant chemicals are adversely affected to some extent by organic matter. The effect may be large or small. Quats are among the least affected in the presence of organic matter.

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS PHENOLIC COMPOUNDS 1. Broad Spectrum Activity Individual phenolics are limited in range with regard to the number of different types of micro-organisms they will kill. However, the number of available phenolics is large and combining several different phenolics can produce an effective formulation. 2. Detergent Compatibility Phenolics are not compatible with the nonionics, the most effective of the hard surface detergents. They are compatible with soaps and/or synthetic anionic detergents. The resulting formulation is, of course, a relatively ineffective detergent product, and as a result, less effective germicide. 3. Oral Toxicity and Skin irritation Most phenolics have a relatively high toxicity rating and are usually skin irritants, especially so in the concentrations in which they are present in the typical formulation. 4. Freedom From Odour All of the phenolics have a noticeable odour and most of them a disagreeable one. 5. High Activity at Alkaline DH Phenolics are most effective against microorganisms at a pH 8 or below. This is usually too low for good detergent action. As the pH increases above 8, germicidal activity decreases. 6. Retention of Activity in Presence of Organic Matter The activity of some Phenolic compounds decreases quite rapidly in the presence of organic matter. The degree will vary with the type of Phenolic, but as a general rule, the phenolics most effective against microorganisms are moderately affected by organic matter. IODOPHORS The type of iodophor always found in the area of detergent/disinfectants is one based on a combination of iodine and nonionic synthetic detergent in an acid medium. The acid is usually phosphoric and the product normally has a pH of 3-4. 1. Broad Spectrum Activity Iodophors are excellent in this respect. 2. Detergent Compatibility As a stated before, the type of iodophor normally encountered is a combination of iodine and nonionic. Unfortunately, since germicidal activity of iodine is highest at an acid pH, the detergent activity of the nonionic is very

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS sharply reduced. 3. Oral Toxicity and Skin Irritation Iodophors exhibit relatively low toxicity and skin irritation. 4. Freedom from Odour Iodophors have a very low odour level and in this respect are not objectionable. However, they cannot be formulated with odour counteractants or other materials that would normally leave an air freshened effect, since the iodine attacks the odour counteractant chemicals, usually creating an unpleasant odour in the process. 5. High Activity at Alkaline pH As stated before, these products require an acid pH for germicidal activity. This, of course, drastically reduces the efficacy of the detergent. It also eliminates the possibility of using inorganic builders sequestrates and chelating agents to enhance detergent activity. 6. Retention of Activity in Presence of organic Matter The presence of organic matter sharply reduces the efficacy of iodophors against microorganisms. PINE OIL This product is obtained by several methods from pinewood. It is a mixture of several different chemicals that vary in their activity against microorganisms. The National Formulary specifies that 95% of the product must distil between 200 and 225 C. This specification tends to fix the types and amounts of chemicals present in the product. A typical pine oil preparation contains 60% pine oil solubilised with soap. Because of certain limitations, to be discussed, these products are frequently fortified by the addition of phenolics. However, it has been found that the phenolics are slowly inactivated over an extended period of time, so that the presence of Phenolic in a pine oil product does not necessarily mean it will be active. The unfortified pine oil formulation must be used in fairly concentrated form, so they are uneconomical for hard surface cleaning and disinfection where large surfaces are involved. 1. Broad Spectrum Activity Pine oil is quite active against the gram-negative organisms, but totally ineffective against many of the gram-positive organisms, such as Staphylococcus Aureus. The addition of a Phenolic is necessary to give activity against the gram positives, but, as pointed out previously, there is a slow inactivation of the Phenolic compound. 2. Detergent Compatibility Pine oils are compatible with soaps and some anionics. Neither type of detergent is really effective for hard surface cleaning nor both, particularly the soaps, will leave a metallic plate if hard water is used. 3. Oral Toxicity and Skin Irritation

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ANOTEC PTY LIMITED LEADERS IN ODOUR CONTROL SOLUTIONS Pine oil itself has low order of toxicity and skin irritation. Combined with phenolics, both toxicity and skin irritation are definitely increased. 4. Freedom From Odour Pine oil itself has a very high odour level, which is objectionable to many people. As an odourant, it is frequently used to mask such malodours as those commonly encountered in poorly maintained rest rooms. 5. High Activity at Alkaline pH Activity of these products is good at fairly high pH. When a Phenolic is present, its activity is, of course, decreased under such conditions. 6. Retention of Activity In Presence of Organic Matter organic matter causes a moderate reduction in the activity of pine oil. As stated previously, a fortified product (containing Phenolic) is adversely affected since organic matter reduces Phenolic activity. Although the information above is quite brief, it shows how and why Anotec decided to include the Anotec range of cleaning products to compliment the odour control range.

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