Smells Like Teen Shampoo

EXPERIMENT Smells Like Teen Shampoo Smells Like Teen Shampoo Abstract Shampoos are an important part of our daily lives and they vary in terms of their smells and cleaning actions. This project involved making shampoo using distillation to extract the key ingredient of a fragrance, essential oil. A variety of plants were used to extract the oils. To understand the chemical ingredients of the oils, two methods of analysis were performed: a process called thin layer chromatography, conducted in-class; and another called gas chromatography-mass spectrometry which was conducted by the Scotch Whisky Research Institute. Both tests revealed the chemicals present in the oils, the latter with a much higher accuracy. Once the shampoo was made, it was tested for pH, ability to clean and the all important ability to foam. To test if the shampoos could clean, horse hair and dolls’ hair were used. Afterwards, the shampoo work was presented in a Dragon’s Den style poster session to other students, teachers and a professional scientist who was as a partner in our project. Overall the shampoos all worked well and a greater understanding and enthusiasm for chemistry was gained. Funding Statement gas chromatography, mass spectrometry and gas Royal Society Partnership Grant. chromatography (GC) olfactrometry to identify the whisky and its components.1 Introduction his project studied the chemistry of the Steam distillation was used to separate the essential production of essential oils, the making of oil from plants. This works by heating the mixture commercial shampoos, what chemicals are above the boiling point of the essential oil allowing T the components to evaporate into the condenser. in shampoos and how to find out what chemicals are in shampoos. The school project at Dornoch The condenser permits the distillate to condense and Academy was performed in partnership with Whyte run off into the collection flask. and Mackay, which allowed a professional scientist Thin layer chromatography (TLC) was then carried to give advice, look at our work and do chemical out on the distillate and pure essential oils, to allow analysis that would otherwise be too expensive separation of the components of each essential or difficult for our school to do. James Pryde is oil and identification. TLC separates mixtures of the chief chemist at Whyte and Mackay and has substances into their component parts, allowing published a paper in which he analysed whisky the distillate to be separated into the compounds taken to the South Pole by the explorer Ernest it is composed of, and by comparison with the Shackleton and used chemical techniques such known pure compounds, the separate components can be identified. Different components separate due to them travelling different distances on the chromatography plate. The emulsifier (in this case polysorbate-20) bonds with a polar water molecule on the left and the non-polar limonene from citrus oils on the right. This allows oil and water to mix and form a shampoo emulsion. [HEADLINE] 38 WWW.YSJOURNAL.COM I ISSUE 17 I ROYAL SOCIETY SPECIAL “Two important ingredients for shampoo: emulsifier to blend the oil and water; foaming agent to form the The distillate was thenbubbles” mixed along with the emulsifier (polysorbate-20) to allow the oils and the water to form an emulsion. The oils do not mix with water normally because the oils are non-polar and the water is polar. The emulsifier is able to bind to both the water and the oils due to it having a long non polar tail and a polar head, this forms a stable emulsion (figure 1). Figure 2: Steam distillation setup by condensing the rising steam and to not char the plant matter. The sand is also a safety precaution to prevent the glass from shattering. The essential oil would gather in the collecting basin (figure 2) Forming the Shampoo: The essential oil extract (which provides the scent) was added to a 250cm3 beaker to which 5cm3 of water was added. The next chemical added Figure 1: Chemistry of emulsion was 30cm3 of sodium laureth sulphate (this is formation the foaming agent in shampoo) which works by encapsulating the dirt molecules by folding itself Sodium laureth sulfate was the foaming agent we around it. It needed to be stirred in well so a magnetic used; its purpose is to give the shampoo the bubbles stirrer was used for a consistent and thorough that are seen when shampoo is used and also to give stir. Then 10cm3 of coco betaine was added and the impression that it is thoroughly cleaning. stirred in to the existing mixture; this was added to reduce irritation to the skin. 2cm3 of polysorbate-20 Method was added and stirred in. Polysorbate-20 is an The main outline of the task was to extract essential emulsifier and which makes it useful in binding other oils from various materials and use them in the components together. Coco Betaine is a surfactant, production of a shampoo. This involved blending and along with polysorbate-20, which bonds the water testing the shampoo to see how it performed and and oil molecules and reduces potential irritation by acted. the sodium laureth sulfate. This is in the soap as it suspends the dirt molecules in the water to make Preparation for distillation: it easier to wash away. Next the essential oils were Firstly the plants were chosen for the distillations to added, only 0.5cm3 was needed due to the intensity extract the essential oils. This included ginger, pine of the fragrances. The mixture was then stirred to needles and citrus fruits such as lemon, orange and ensure total blending of all the components involved. grapefruit. These were all obtained from local shops except pine needles, which came from a pine tree in Thin Layer Chromatography: the school. These plants needed to be cut or grated One drop of the essential oil dissolved in 1 ml hexane into smaller pieces to achieve a sufficient yield due to – along with two pure sample terpenes that were the increase in surface area. Water and a few anti- believed to be present in the essential oil – was bumping granules were added to the plant matter. spotted onto TLC paper and put it in a glass jar with These granules are made from aluminium oxide and 0.5 ml of solvent (Figure 3). After the solvent had run help ensure smooth boiling. to 1cm from the top of the TLC paper, the TLC was removed and soaked in p-anisaldehyde solution or a permanganate dip. This procedure was a modified Carrying out the distillation of plant matter: version of a published one.2 The TLC strip was then A heating plate combined with a sand basin provided gently heated on a heating mantle to evaporate a consistent and gentle heat. This meant that the the solvent and reveal the terpenes present in plant matter’s extract could be collected efficiently the essential oil. Thin layer chromatography was ROYAL SOCIETY SPECIAL I ISSUE 17 I WWW.YSJOURNAL.COM 39 EXPERIMENT Shampoo analysis Figure 3: Spotting essential oils onto Thin Layer Figure 4: Shampoo mixed with green ink. Note how Chromatography plates there is no ink in the foam, a good sign. attempted on the distillates but the yields of oils The next test was the dirt test, or rather ink test as appeared to be too low for detection. Commercially ink was used instead of dirt. This involved putting 2 bought essential oils were used for the thin layer drops of shampoo and one drop of ink into 10 ml of chromatography analysis instead and the steam distilled water in a test tube then shaken vigorously distillates were used for the shampoo. and left to settle. This would produce foam. The ideal outcome is for Results Various fragrances of distillate were created, such there to be no ink/dirt in the foam, for it is meant to as: lemon, lime and ginger. The distillations were be in the water so that when you wash your hair it a success, all groups produced a good product. easily runs off your head. If it stayed in the foam, it However the distillates by themselves proved not could easily be redistributed into your hair as foam to be concentrated enough and so essential oils is harder to wash out than water (Figure 4). The were bought commercially and also added in tiny final tests were an analysis of the foam produced quantities, such as ylang ylang and pine oil. upon vigorous shaking. 50 ml of 1% shampoo was put into a 250 ml graduated cylinder and shaken 10 “red would mean it was times, the volume of the foam was then recorded as was the size of the bubbles, they could be either acidic and so possibly small, medium or large. A good shampoo should irritant but would make produce a foam volume of around twice the original volume of the shampoo, which our shampoo did3 . the outer layer of hair The bubbles of the foam should also be small as it lay flat and so make hair means the retention time of the foam will be longer. At the same time as measuring the volume of foam There were severalseem tests smoother” done to analyze the the time of retention was also measured, a good shampoo based on published methods3 , they are as shampoo will keep the same volume for around 5 follows: the pH test, which was done in order to see minutes. Our shampoos managed to do this. To test if the shampoo was safe enough for even the most if the shampoos could clean, horse hair and dolls’ sensitive of scalps, it was done using pH paper strips hair were used.

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