In chemistry, a formulation is a mixture or blend of different chemicals, typically designed to achieve a specific function or purpose. The term can be applied to a wide range of products, from cosmetics and pharmaceuticals to paints and pesticides.
For example, the mix of reagents used to make bubble water is a formulation. You can prepare your own bubble mixture using the following ingredients:
- Glycerine.
- Sugar.
- Water.
- Dish liquid.
Using trial and error, prepare a recipe with an exact ratio of ingredients that gives you the perfect bubbles every time. Don’t forget to record the proportion of ingredients used so that you can recreate it in the future. This ‘perfect recipe’ that you’ve just invented, which contains particular ingredients in definite quantities and is specifically designed to give you an end product with desired characteristics, is a formulation.
- This article is about formulations in chemistry.
- First, we will introduce you to the definition of formulation.
- After that, we'll go through the types of formulations.
- Then, we will have a brief overview of the properties of an ideal formulation.
- Finally, we will finish the topic with a few examples of formulations, explaining their key functions and uses. This includes pharmaceutical formulations.
Formulation: chemistry
As we saw above, a formulation is a mixture that has been designed as a useful product.
Formulations are designed to have beneficial and desired properties that fulfil a specific purpose. Like your bubble mixture, they not only contain a particular combination of ingredients but these ingredients are combined in carefully measured quantities according to an exact formula.
Formulations may include active ingredients, solvents, stabilizers, preservatives, and other additives that enhance performance or stability. They are usually designed to provide a specific set of physical, chemical, or biological properties, such as colour, viscosity, texture, or shelf-life. Formulations are often developed through a process of trial and error, and may undergo extensive testing to ensure their safety, efficacy, and consistency.
Formulations are made up of many different ingredients, which can be molecules, elements, mixtures, or chemical compounds. However, formulations themselves are always mixtures. This means that the chemical compounds or ingredients within them aren't chemically bonded together. Check out the articles Atoms, Elements and Compounds and Mixtures for more information about the differences between mixtures and compounds.
Types of formulation
We can classify formulations into different types, such as by their state of matter. For example, you can find solid, liquid, gaseous, and aqueous formulations. But these are broad categories that can be further split into even more varieties. For example, here are a few particular types of liquid formulations that you might be interested in.
| Type of formulation | Definition | Example |
| Solution | A uniform mixture of a solid, liquid or gas dissolved in another liquid. | A sugar solution. Here, sugar (a solid) is dissolved in water (a liquid). This mixture is uniform, as it all looks the same - you cannot see the individual sugar and water molecules. |
| Suspension | A non-uniform mixture of insoluble solid particles held within a liquid. | Orange juice with pulp. Here, you can clearly see the undissolved bits of pulp within the liquid juice. When left to stand, the heavier pulp sinks to the bottom of the carton. |
| Emulsion | A non-uniform mixture of two liquids that don't dissolve in each other, held together by emulsifiers. | Oil in water. Despite both being liquids, oil and water don't dissolve in each other - you can clearly see the insoluble oil droplets within the mixture. When left undisturbed, the liquids separate into layers. We can add special chemicals called emulsifiers to prevent the layers from separating, which allows us to create formulations like butter and mayonnaise. |
Properties of formulations
The ideal properties of a formulation depend on its use. However, there are some common properties looked for in many formulations.
For example, safety is an important property of most formulations. The formulation needs to be stable for a certain period of time, be able to withstand temperature changes, and cope with different environmental conditions. Its ingredients shouldn't react with each other, and the overall product should also retain its efficacy over time. However, the manufacturers that design formulations might also consider the following properties:
- Taste.
- Smell.
- Consistency.
- Colour.
- Melting and boiling point.
- Whether it separates into multiple layers, much like oil and water, or remains as one uniform mixture.
Here's a simple activity that you can do to explore formulations a little further:
- Grab a jar of mustard or a bottle of ketchup from the kitchen. These condiments are both formulations.
- Go through the list of ingredients printed on the packaging.
- Use the internet to research each ingredient. What are their typical uses and characteristics, and what properties do they give the final formulation?
You should see that the sauces both contain many ingredients that all contribute to the end product in different ways, helping to achieve its desired properties. For example, mustard often contains turmeric (which adds a bright yellow colour), citric acid (a natural preservative), and xanthan gum (which stops the condiment from splitting). The two condiments might be simple foods that you don't think twice about, but many properties need to be considered when they are designed - their taste, texture, visual appeal, and more.
Examples of formulations
Now that we've learned the definition of formulation and seen some of their ideal properties, let's look at examples of formulations. You should see that formulations are used in all sorts of fields, ranging from the food and sports industries to agriculture and medicine. We'll then take a named formulation and examine both its ingredients and properties in more detail.
Common examples of formulations include:
- Paints, varnishes, and sealants.
- Fuels and cleaning products.
- Fertilisers and pesticides.
- Alloys, such as those used in tins and car parts.
- Cosmetics like nail varnish and lipstick.
- Toiletries, from soap to toothpaste and shaving foam.
- Medicines and drugs.
- Food.
Alloys are an example of a solid formulation.
An alloy is a mixture of two or more metals that has better strength and resistance than the individual metal.
Bronze, an alloy of copper, tin, and sometimes other metals, is used in sculptures and monuments. The outer layer of bronze oxidises into copper carbonate when it touches air thanks to the copper it contains, stopping the alloy underneath from corroding. This makes bronze extremely durable. Adding different proportions of metals to bronze changes its properties and thus its applications. To make a relatively frictionless type of bronze, you add around 6-8% lead, whilst to increase its resonance, you use a mixture of 20% tin and 80% copper.
Fig. 1: The Alan Turing memorial in Manchester, England, is made from the alloy bronze.Image credits: commons.wikimedia.org, public domain
Formulation uses
Most pharmaceutical medicines and drugs are formulations of some sort. As well as the active ingredient, they contain colourants, flavourings, stabilising agents, pH regulators, bulking agents, and more. Although these additional ingredients may not make you feel better, they are vital components of the formulation and are known as inactive ingredients.
Pharmaceutical formulations
The active ingredient in a formulation is the component directly responsible for its desired effect. The inactive ingredients are all the other ingredients in a formulation that don't contribute to its direct effect, but give it other desirable properties.
The numerous ingredients they contain contribute to the many required properties of pharmaceutical formulations. Whilst the active ingredient is what makes you feel better and helps treat your condition, the inactive ingredients ensure that the formulation is safe and stable, can be easily taken in the right quantities, has a neutral (if not pleasant) taste, and doesn't cause any side effects.
Fig. 2: Calpol, an example of pharmaceutical formulation by Wellcome Library, London, CC BY 4.0, via Wikimedia Commons
Lemsip, a medicine taken to reduce fever, is a pharmaceutical formulation. Its active ingredients are paracetamol and phenylephrine hydrochloride. While paracetamol helps reduces fever and pain, phenylephrine hydrochloride reduces congestion and helps ease blocked noses. However, Lemsip can also contain aspartame, which masks its bitter taste, or gelatin, which is used to package the medicine up into a hard capsule. These inactive ingredients both make taking the formulation much more pleasant.
You should remember that formulation chemistry is a growing field. Chemists spend a lot of time and money researching the perfect ingredients for their products and are continuously updating their methods. Like with your bubble mixture, achieving the best possible, highest-performing formulation requires trial, error, and a large amount of patience! But it can't be denied that these mixtures are a useful part of our lives. Take a look around - now that you've read this article, how many formulations can you spot nearby?
Formulations - Key takeaways
- A formulation is a mixture that has been designed as a useful product.
- Formulations are designed for a particular purpose. They contain carefully measured ingredients that give them desired properties.
- When designing formulations, properties such as safety, stability, efficacy, taste, colour, and texture are often considered. However, the properties of a particular formulation depend on its purpose.
- Examples of formulations in our daily lives include fertilisers, medicines, toiletries, cosmetics, and sauces.
References
- Image of Calpol, License deed: https://creativecommons.org/licenses/by/4.0/
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