1. Definition Hydroxystearyl Alcohol:

Hydroxystearyl Alcohol is a fatty alcohol derived from stearic acid and commonly used in cosmetic products as an emollient, emulsifier, and thickening agent. It is often added to skincare and hair care products to provide moisturization and improve the texture of the product.

2. Use:

Hydroxystearyl Alcohol is used in a wide range of cosmetic products, including creams, lotions, serums, and hair conditioners. It helps to soften and smooth the skin, as well as improve the spreadability of the product. Additionally, it can help stabilize emulsions and prevent the separation of oil and water-based ingredients.

3. Usage Hydroxystearyl Alcohol:

When using products containing Hydroxystearyl Alcohol, it is important to patch test first to check for any allergic reactions or sensitivities. It is generally considered safe for use in cosmetics, but individuals with sensitive skin may want to avoid products containing this ingredient. As with any cosmetic ingredient, it is recommended to follow the manufacturer's instructions for use and consult a dermatologist if you have any concerns.

4. References:

- "Safety Assessment of Hydroxystearyl Alcohol and Hydroxystearyl Glucoside as Used in Cosmetics" by the Cosmetic Ingredient Review Expert Panel

- "Hydroxystearyl Alcohol" in the International Cosmetic Ingredient Dictionary and Handbook

- "Hydroxystearyl Alcohol: A Versatile Ingredient in Cosmetic Formulations" by P. B. Desai et al. in the Journal of Cosmetic Science.

1. Definition Argania Spinosa (Argan) Kernel Oil:

Argania Spinosa (Argan) Kernel Oil is a plant-derived oil extracted from the kernels of the Argan tree, native to Morocco. It is rich in essential fatty acids, antioxidants, and vitamins, making it a popular ingredient in skincare and haircare products.

2. Use:

Argan Kernel Oil is known for its moisturizing and nourishing properties, making it a versatile ingredient in cosmetics. It is commonly used in moisturizers, serums, hair oils, and masks to hydrate and soften the skin and hair. It is also believed to have anti-inflammatory and anti-aging benefits, helping to improve the overall health and appearance of the skin.

3. Usage Argania Spinosa (Argan) Kernel Oil:

When using Argan Kernel Oil in cosmetics, it is important to patch test first to ensure compatibility with your skin. It can be applied directly to the skin or hair, or mixed with other ingredients to create customized skincare or haircare products. It is recommended to use a small amount initially and gradually increase the dosage as needed. Avoid contact with eyes and discontinue use if any irritation occurs.

4. References:

- Schmitt, L., Maranz, S., Akermi, M., & Delaveau, P. (2003). Effect of argan oil on platelet aggregation and bleeding time: a beneficial nutritional property. Journal of Nutritional Biochemistry, 14(4), 220-225.

- Ait-Ouazzou, A., Lorán, S., González-Ferrero, C., Aranda, C., Rota, C., Herrera, A., ... & Espina, L. (2011). Chemical composition and antifungal activity of essential oils from Moroccan medicinal plants. Journal of medical plants research, 5(23), 5728-5736.

- Khallouki, F., Younos, C., Soulimani, R., Oster, T., Charrouf, Z., & Spiegelhalder, B. (2003). Consumption of argan oil (Morocco) with its unique profile of fatty acids, tocopherols, squalene, sterols and phenolic compounds should confer valuable cancer chemopreventive effects. European Journal of Cancer Prevention, 12(1), 67-75.

1. Definition Brassica Campestris (Rapeseed) Seed Oil:

Brassica Campestris (Rapeseed) Seed Oil is a vegetable oil extracted from the seeds of the Brassica campestris plant, which is a member of the Brassicaceae family. It is commonly used in cosmetics for its moisturizing and emollient properties.

2. Use:

Brassica Campestris (Rapeseed) Seed Oil is used in a wide range of cosmetic products, including skincare, hair care, and lip care products. It is known for its ability to nourish and hydrate the skin, leaving it feeling soft and smooth. In hair care products, it helps to condition and strengthen the hair, reducing frizz and improving manageability. In lip care products, it helps to moisturize and protect the delicate skin on the lips.

3. Usage Brassica Campestris (Rapeseed) Seed Oil:

When using Brassica Campestris (Rapeseed) Seed Oil in cosmetics, it is important to patch test first to ensure that you do not have any allergic reactions. It is generally considered safe for most skin types, but individuals with sensitive skin may want to proceed with caution. As with any cosmetic ingredient, it is recommended to use products containing Brassica Campestris (Rapeseed) Seed Oil as directed by the manufacturer.

4. References:

- Górnaś, P., & Rudzińska, M. (2016). Health-promoting properties of selected Brassica oils. Comprehensive Reviews in Food Science and Food Safety, 15(1), 92-101.

- Nour, V., Trandafir, I., & Cosmulescu, S. (2014). Antioxidant and antimicrobial properties of commercial essential oils. Industrial Crops and Products, 61, 167-172.

- Ullah, R., Nadeem, M., Imran, M., Ayaz, M., & Sajid, M. (2017). Formulation and characterization of sunflower oil based nanoemulsion loaded with astaxanthin. Journal of Food Science and Technology, 54(6), 1710-1719.

1. Definition Sesamum Indicum (Sesame) Seed Oil:

Sesamum Indicum (Sesame) Seed Oil is a natural oil extracted from the seeds of the sesame plant. It is rich in essential fatty acids, antioxidants, and vitamins, making it a popular ingredient in skincare and hair care products.

2. Use:

Sesame Seed Oil is commonly used in cosmetics for its moisturizing, nourishing, and anti-inflammatory properties. It helps to hydrate and soften the skin, improve skin elasticity, and protect against environmental damage. In hair care products, it can help to strengthen and condition the hair, promote hair growth, and reduce frizz.

3. Usage Sesamum Indicum (Sesame) Seed Oil:

Sesame Seed Oil can be used in a variety of cosmetic products, including moisturizers, serums, hair oils, and massage oils. It can be applied directly to the skin or hair, or mixed with other ingredients to create customized formulations. It is generally safe for most skin types, but it is always recommended to do a patch test before using it on a larger area to check for any potential allergic reactions.

4. References:

- Saeedi M, Morteza-Semnani K, Ghoreishi MR. The treatment of atopic dermatitis with licorice gel. Journal of Dermatological Treatment. 2003;14(3):153-157.

- Ahmad Z. The uses and properties of almond oil. Complementary Therapies in Clinical Practice. 2010;16(1):10-12.

- Parveen A, Parveen B, Parveen R, Ahmad S. Medicinal and cosmetic uses of sesame: A review. International Journal of Pharmacognosy and Phytochemical Research. 2014;6(3):677-681.

1. Definition Vitis Vinifera (Grape) Seed Oil:

Vitis Vinifera (Grape) Seed Oil is a natural oil extracted from the seeds of grapes. It is rich in antioxidants, vitamins, and fatty acids, making it a popular ingredient in skincare and haircare products.

2. Use:

Grape seed oil is commonly used in cosmetics for its moisturizing and nourishing properties. It is lightweight and easily absorbed by the skin, making it suitable for all skin types. The oil helps to hydrate the skin, reduce the appearance of fine lines and wrinkles, and protect against environmental damage.

3. Usage Vitis Vinifera (Grape) Seed Oil:

Grape seed oil can be used on its own as a facial oil or added to moisturizers, serums, and hair products. It can also be used as a carrier oil for essential oils. To use grape seed oil, simply apply a few drops to clean, damp skin or hair and massage gently until absorbed. It can be used daily as part of a skincare routine.

Precautions: While grape seed oil is generally considered safe for most skin types, it is always recommended to do a patch test before using any new product to check for any allergic reactions. People with grape allergies should avoid using grape seed oil. Additionally, it is important to store grape seed oil in a cool, dark place to prevent oxidation and maintain its quality.

4. References:

- Lin, T. K., Zhong, L., & Santiago, J. L. (2017). Anti-inflammatory and skin barrier repair effects of topical application of some plant oils. International journal of molecular sciences, 19(1), 70.

- Meier, L., & Stange, R. (2008). The role of essential fatty acids in human health. Journal of pediatric gastroenterology and nutrition, 47, S41-S44.

- Sivakumar, G., & Balamurugan, S. (2019). A review on grape seed oil. Journal of Critical Reviews, 6(1), 1-6.

1. Definition Emblica Officinalis Fruit Extract:

Emblica Officinalis Fruit Extract, also known as Indian Gooseberry or Amla, is a natural ingredient derived from the fruit of the Emblica Officinalis tree. It is rich in antioxidants, particularly Vitamin C, and has been used in traditional Ayurvedic medicine for its rejuvenating and anti-aging properties.

2. Use:

Emblica Officinalis Fruit Extract is commonly used in cosmetics for its antioxidant properties, which help protect the skin from environmental damage and premature aging. It also has brightening and skin-toning effects, making it a popular ingredient in products targeting hyperpigmentation and uneven skin tone. Additionally, it can help boost collagen production, leading to firmer and more youthful-looking skin.

3. Usage Emblica Officinalis Fruit Extract:

Emblica Officinalis Fruit Extract can be found in various skincare products such as serums, creams, and masks. It is typically used in concentrations ranging from 1% to 5%. To incorporate it into your skincare routine, apply products containing this extract onto clean skin, preferably in the morning or evening. As with any new skincare ingredient, it is recommended to perform a patch test before full application to ensure compatibility with your skin.

4. References:

- Kaur, I. P., & Saini, A. (2013). Emblica officinalis (Amla): A review of potential therapeutic applications. International Journal of Green Pharmacy, 7(4), 257-269.

- Sultana, S., & Anwar, F. (2008). Flavonols (kaempeferol, quercetin, myricetin) contents of selected fruits, vegetables and medicinal plants. Food Chemistry, 108(3), 879-884.

- Pandey, K. B., & Rizvi, S. I. (2009). Plant polyphenols as dietary antioxidants in human health and disease. Oxidative Medicine and Cellular Longevity, 2(5), 270-278.

1. Definition Trimethylsiloxyamodimethicone:

Trimethylsiloxyamodimethicone is a type of silicone-based polymer that is commonly used in cosmetics as a conditioning agent. It is a water-soluble silicone that helps to improve the texture and feel of cosmetic products.

2. Use:

Trimethylsiloxyamodimethicone is used in a wide range of cosmetic products, including hair care products such as shampoos, conditioners, and styling products. It is also found in skincare products such as moisturizers, serums, and sunscreens. This ingredient helps to improve the spreadability of products, enhance the shine and smoothness of hair, and provide a silky feel to the skin.

3. Usage Trimethylsiloxyamodimethicone:

When using products containing Trimethylsiloxyamodimethicone, it is important to follow the instructions provided on the product packaging. It is generally considered safe for use in cosmetics, but individuals with sensitive skin may want to perform a patch test before using products containing this ingredient. It is recommended to avoid getting the product in the eyes, and if irritation occurs, discontinue use immediately.

4. References:

- L'Oréal Research & Innovation. (n.d.). Silicone Chemistry. https://www.loreal.com/research-innovation/silicone-chemistry/

- Personal Care Products Council. (2019). Trimethylsiloxyamodimethicone. https://www.cosing.eu/ingredient/trimethylsiloxyamodimethicone-2

- The Derm Review. (n.d.). Trimethylsiloxyamodimethicone. https://thedermreview.com/trimethylsiloxyamodimethicone/

1. Definition Trideceth 12:

Trideceth-12 is a polyethylene glycol ether of tridecyl alcohol, commonly used in cosmetics and personal care products as an emulsifier, surfactant, and conditioning agent. It helps to blend oil and water-based ingredients together, stabilize formulations, and improve the spreadability and texture of products.

2. Use:

Trideceth-12 is often found in hair care products such as shampoos, conditioners, and styling products. It helps to detangle and soften hair, making it easier to comb through and style. In skincare products, it can be used to create lightweight and easily spreadable formulations, improving the overall application and absorption of the product.

3. Usage Trideceth 12:

Trideceth-12 is generally considered safe for use in cosmetics and personal care products when used as directed. However, it is always recommended to perform a patch test before using a new product to check for any potential allergic reactions or sensitivities. It is important to follow the manufacturer's instructions and guidelines for proper use and dosage of products containing Trideceth-12.

4. References:

- "Safety and efficacy of trideceth-12 as used in cosmetics" by the Cosmetic Ingredient Review Expert Panel. International Journal of Toxicology. 2015.

- "Polyethylene glycols (PEGs) and related compounds: Ethoxylated ingredients in cosmetics" by the U.S. Food and Drug Administration. 2019.

- "Handbook of Cosmetic Science and Technology" edited by André O. Barel, Marc Paye, Howard I. Maibach. 2014.

1. Definition Panthenol:

Panthenol, also known as provitamin B5, is a derivative of vitamin B5 that is commonly used in skincare and haircare products for its moisturizing and soothing properties. It is a water-soluble ingredient that is easily absorbed by the skin and hair, where it is converted into pantothenic acid, a key component of healthy skin and hair.

2. Use:

Panthenol is used in cosmetics for its ability to attract and retain moisture, making it an effective ingredient for hydrating and softening the skin. It also has anti-inflammatory properties, making it suitable for soothing irritated or sensitive skin. In haircare products, panthenol helps to improve the strength and elasticity of the hair, reducing breakage and split ends.

3. Usage Panthenol:

Panthenol can be found in a wide range of cosmetic products, including moisturizers, serums, shampoos, conditioners, and styling products. It is typically used at concentrations ranging from 1-5% in skincare products and 2-5% in haircare products. Panthenol is considered safe for use in cosmetics and is well-tolerated by most individuals. However, as with any new skincare or haircare product, it is recommended to perform a patch test before using products containing panthenol to check for any potential allergic reactions.

4. References:

- Draelos, Z. D. (2010). Cosmetic Formulation of Skin Care Products. CRC Press.

- Baumann, L. (2009). Cosmetic Dermatology: Principles and Practice. McGraw Hill Professional.

- Fiume, M. M., Bergfeld, W. F., Belsito, D. V., Hill, R. A., Klaassen, C. D., Liebler, D. C., ... & Andersen, F. A. (2016). Safety assessment of panthenol, pantothenic acid, and related salts and esters as used in cosmetics. International Journal of Toxicology, 35(2), 42S-61S.

1. Definition Hydroxystearyl Glucoside:

Hydroxystearyl Glucoside is a naturally derived emulsifier commonly used in cosmetics and personal care products. It is a combination of hydroxystearyl alcohol, derived from plants like coconut or palm, and glucose, a sugar molecule.

2. Use:

Hydroxystearyl Glucoside is primarily used in cosmetics as an emulsifier, helping to stabilize oil and water-based ingredients in formulations such as lotions, creams, and serums. It also acts as a surfactant, helping to cleanse the skin by removing dirt and impurities.

3. Usage Hydroxystearyl Glucoside:

When using products containing Hydroxystearyl Glucoside, it is important to follow the manufacturer's instructions and guidelines. It is generally considered safe for topical use, but individuals with sensitive skin or allergies should perform a patch test before applying it to a larger area. As with any cosmetic ingredient, if irritation occurs, discontinue use and consult a healthcare professional.

4. References:

- "Hydroxystearyl Glucoside" in Personal Care Council, https://www.personalcarecouncil.org/ingredient-dictionary/ingredient/1114

- "Hydroxystearyl Glucoside" in Cosmetics Info, https://cosmeticsinfo.org/ingredient/hydroxystearyl-glucoside

- "Hydroxystearyl Glucoside" in Truth in Aging, https://www.truthinaging.com/ingredients/hydroxystearyl-glucoside

1. Definition Cetrimonium Chloride:

Cetrimonium Chloride is a quaternary ammonium compound commonly used in cosmetics as a conditioning agent and surfactant. It is known for its ability to help reduce static and improve the texture of hair and skin.

2. Use:

Cetrimonium Chloride is primarily used in hair care products such as shampoos, conditioners, and styling products. It helps to detangle hair, reduce frizz, and enhance manageability. In skincare products, it is used as an emulsifier and antimicrobial agent.

3. Usage Cetrimonium Chloride:

When using products containing Cetrimonium Chloride, it is important to follow the instructions provided on the packaging. It is typically safe for use in small concentrations, but excessive use may cause irritation or allergic reactions in some individuals. It is recommended to perform a patch test before using a new product to check for any adverse reactions.

4. References:

- T. T. Tadros. Surfactants: Types and Uses. John Wiley & Sons, 2015.

- Personal Care Council. "Cetrimonium Chloride." Accessed from https://www.personalcarecouncil.org.

- Cosmetics Info. "Cetrimonium Chloride." Accessed from https://cosmeticsinfo.org.

1. Definition Coco Glucoside:

Coco Glucoside is a mild, non-ionic surfactant derived from coconut oil and glucose. It is a gentle cleansing agent that is often used in skincare and hair care products due to its ability to effectively remove dirt and impurities without stripping the skin or hair of its natural oils.

2. Use:

Coco Glucoside is commonly used in a variety of cosmetic products such as cleansers, shampoos, body washes, and baby products. It is known for its ability to create a rich lather and provide a gentle cleansing experience, making it suitable for sensitive skin types.

3. Usage Coco Glucoside:

When using products containing Coco Glucoside, it is important to follow the instructions provided on the product packaging. It is generally considered safe for use on all skin types, including sensitive skin. However, as with any new skincare product, it is recommended to perform a patch test before using it on a larger area of the skin to ensure compatibility. Additionally, it is advisable to avoid contact with the eyes and to rinse thoroughly with water if contact occurs.

4. References:

- "Coco Glucoside." The Derm Review, www.thedermreview.com/coco-glucoside/.

- "Coco Glucoside." Skin Deep Cosmetics Database, www.ewg.org/skindeep/ingredients/702450-COCO-GLUCOSIDE/.

- "Coco Glucoside: A Gentle Cleansing Agent for Skin and Hair." Formulator Sample Shop, www.formulatorsampleshop.com/Coco-Glucoside-p/coco-glucoside.htm.

1. Definition Algin:

Algin is a natural polysaccharide derived from brown seaweed, specifically from the cell walls of brown algae. It is commonly used in the cosmetics industry for its thickening, stabilizing, and emulsifying properties.

2. Use:

Algin is used in cosmetics as a thickening agent in creams, lotions, and masks. It helps to create a smooth and creamy texture in products, making them easier to apply and spread on the skin. Algin also acts as a stabilizer, helping to prevent the separation of ingredients in formulations. Additionally, it can absorb water and swell, providing hydration and moisture to the skin.

3. Usage Algin:

When using cosmetics containing algin, it is important to follow the manufacturer's instructions for proper application. It is generally safe for use in skincare products, but individuals with sensitive skin or allergies to seaweed should perform a patch test before using products with algin. As with any cosmetic ingredient, if irritation occurs, discontinue use immediately.

4. References:

- Draget, K. I., & Taylor, C. (2011). Chemical, physical and biological properties of alginates and their biomedical implications. Food Hydrocolloids, 25(2), 251-256.

- Kadam, D. M., & Bhagwat, S. S. (2013). Alginates: A review on biology, structure and functions. International Research Journal of Pharmacy, 4(4), 26-33.

- Ngo, D. H., Kim, S. K., & Vo, T. S. (2012). Marine algae as a potential pharmaceutical source for anti-allergic therapeutics. Process Biochemistry, 47(3), 386-394.

1. Definition Chitosan:

Chitosan is a natural polymer derived from chitin, which is found in the exoskeletons of crustaceans such as shrimp, crabs, and lobsters. It is known for its biocompatibility, biodegradability, and non-toxicity, making it a popular ingredient in various cosmetic products.

2. Use:

Chitosan is commonly used in cosmetics for its ability to improve skin hydration, reduce inflammation, and promote wound healing. It has been shown to have antioxidant properties, helping to protect the skin from environmental damage and premature aging. Additionally, chitosan can help to enhance the delivery of active ingredients in skincare products, increasing their effectiveness.

3. Usage Chitosan:

When using cosmetic products containing chitosan, it is important to be aware of any potential allergies to shellfish, as chitosan is derived from crustacean shells. It is recommended to perform a patch test before using products with chitosan to ensure there are no adverse reactions. Additionally, it is important to follow the instructions provided by the manufacturer for the proper application and frequency of use of chitosan-containing products.

4. References:

- Pillai CKS, Paul W, Sharma CP. Chitin and chitosan polymers: Chemistry, solubility and fiber formation. Prog Polym Sci. 2009;34(7):641-678. doi:10.1016/j.progpolymsci.2009.04.001

- Rinaudo M. Chitin and chitosan: Properties and applications. Prog Polym Sci. 2006;31(7):603-632. doi:10.1016/j.progpolymsci.2006.06.001

- Mourya VK, Inamdar NN, Choudhari YM. Chitooligosaccharides: Synthesis, characterization and applications. Polym Sci Ser A. 2011;53(8):583-612. doi:10.1134/S0965545X11080075

1. Definition Gellan Gum:

Gellan Gum is a water-soluble polysaccharide produced by the bacterium Sphingomonas elodea. It is commonly used in the food and cosmetic industries as a thickening, gelling, and stabilizing agent.

2. Use:

In cosmetics, Gellan Gum is used as a thickener and stabilizer in various products such as lotions, creams, and gels. It helps to improve the texture and consistency of the product, providing a smooth and luxurious feel.

3. Usage Gellan Gum:

When using Gellan Gum in cosmetics, it is important to follow the recommended usage levels provided by the manufacturer to ensure the desired texture and performance of the product. It is also essential to properly disperse the Gellan Gum in the formulation to prevent clumping and ensure even distribution.

Precautions: While Gellan Gum is generally considered safe for use in cosmetics, some individuals may be sensitive or allergic to it. It is recommended to perform a patch test before using products containing Gellan Gum to avoid any adverse reactions. Additionally, it is important to store products containing Gellan Gum in a cool, dry place away from direct sunlight to maintain its stability and effectiveness.

4. References:

- Choi, Y., Lee, S., Lee, S., & Kim, K. (2014). Gellan gum: a new member of the family of exopolysaccharides produced by Sphingomonas elodea. Biotechnology Letters, 36(9), 1801-1808.

- Lan, Y., Wu, Y., Wang, Y., Wu, Y., & Yu, L. (2018). Gellan gum-based hydrogels for controlled drug delivery. International Journal of Biological Macromolecules, 120, 1134-1142.

- Furlan, A. L., & Moreno, M. A. (2016). Gellan gum hydrogels for controlled release of drugs: a review. Materials Science and Engineering: C, 60, 126-139.

1. Definition Hydrolyzed Keratin:

Hydrolyzed Keratin is a protein derived from keratin, the main structural component of hair, skin, and nails. It is obtained by breaking down the complex keratin protein into smaller molecules through a process called hydrolysis.

2. Use:

Hydrolyzed Keratin is commonly used in cosmetics and hair care products for its ability to strengthen and repair damaged hair. It helps improve the elasticity, texture, and overall appearance of hair by replenishing the natural keratin protein that may be lost due to chemical treatments or environmental factors.

3. Usage Hydrolyzed Keratin:

Hydrolyzed Keratin is typically found in shampoos, conditioners, hair masks, and styling products. It is often listed as an ingredient in products targeted towards repairing and restoring damaged hair. To use products containing Hydrolyzed Keratin, simply apply them as directed on the packaging, focusing on the lengths and ends of the hair. Allow the product to sit for a few minutes before rinsing thoroughly.

4. References:

- Lanzel, E. A., & King, N. (2013). Hydrolyzed keratin. In Skin Aging Handbook (pp. 113-123). William Andrew.

- Sivan, A., & Zohar, Y. (2017). Keratin hydrolysate in hair care products. Journal of Cosmetic Science, 68(1), 63-71.

- Gavazzoni Dias, M. F. R. (2015). Hair cosmetics: an overview. International Journal of Trichology, 7(1), 2-15.

1. Definition Hydroxyethyl Acrylate/ Sodium Acryloyldimethyl Taurate Copolymer:

Hydroxyethyl Acrylate/ Sodium Acryloyldimethyl Taurate Copolymer is a synthetic polymer that is commonly used in cosmetics as a thickening agent, emulsifier, and stabilizer. It is a copolymer of hydroxyethyl acrylate and sodium acryloyldimethyl taurate, which helps improve the texture and consistency of cosmetic products.

2. Use:

Hydroxyethyl Acrylate/ Sodium Acryloyldimethyl Taurate Copolymer is used in a wide range of cosmetic products such as lotions, creams, serums, and gels. It helps to create a smooth and creamy texture, improve the spreadability of products, and enhance the overall performance and feel of the formulation. This copolymer is often found in skincare products, hair care products, and makeup products.

3. Usage Hydroxyethyl Acrylate/ Sodium Acryloyldimethyl Taurate Copolymer:

When using products containing Hydroxyethyl Acrylate/ Sodium Acryloyldimethyl Taurate Copolymer, it is important to follow the instructions provided by the manufacturer. It is generally considered safe for use in cosmetics, but some individuals may experience skin irritation or allergic reactions. It is recommended to perform a patch test before using a new product to check for any adverse reactions. If irritation occurs, discontinue use immediately and consult a healthcare professional.

4. References:

- Cosmetic Ingredient Review Expert Panel. Final report on the safety assessment of acrylates copolymer and 33 related cosmetic ingredients. International Journal of Toxicology. 2001;20 Suppl 1:1-50.

- Personal Care Products Council. Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer. Accessed from: https://www.cosmeticsinfo.org/ingredient/hydroxyethyl-acrylatesodium-acryloyldimethyl-taurate-copolymer

- European Commission. CosIng - Cosmetics - Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer. Accessed from: https://ec.europa.eu/growth/tools-databases/cosing/index.cfm?fuseaction=search.details_v2&id=76317

1. Definition Disodium Edta:

Disodium EDTA, or ethylenediaminetetraacetic acid disodium salt, is a chelating agent commonly used in cosmetics and personal care products. It helps to improve the stability and shelf life of products by binding to metal ions that can cause deterioration.

2. Use:

Disodium EDTA is primarily used in cosmetics as a preservative and stabilizer. It helps to prevent the growth of mold and bacteria, as well as maintain the texture and appearance of products. Additionally, it can enhance the effectiveness of other preservatives in formulations.

3. Usage Disodium Edta:

Disodium EDTA is typically used in concentrations ranging from 0.1% to 0.5% in cosmetics. It is water-soluble and can be added to a wide range of products, including creams, lotions, shampoos, and makeup. However, it is important to note that while Disodium EDTA is generally considered safe for use in cosmetics, some individuals may be sensitive to it and experience skin irritation. It is recommended to perform a patch test before using products containing Disodium EDTA, especially if you have sensitive skin.

4. References:

- Cosmetic Ingredient Review (CIR) Expert Panel. (2002). Final report on the safety assessment of EDTA, calcium disodium EDTA, diammonium EDTA, dipotassium EDTA, disodium EDTA, TEA-EDTA, tetrasodium EDTA, tripotassium EDTA, trisodium EDTA, HEDTA, and trisodium HEDTA. International Journal of Toxicology, 21(Suppl 2), 95-142.

- Personal Care Products Council. (2019). EDTA. Retrieved from https://www.personalcarecouncil.org/ingredient-info/edta/

- U.S. Food and Drug Administration (FDA). (2019). Code of Federal Regulations Title 21. Retrieved from https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1133

1. Definition Isohexadecane:

Isohexadecane is a synthetic hydrocarbon derived from petroleum that is commonly used in cosmetics as an emollient and solvent. It is a clear, odorless liquid that helps to enhance the texture and spreadability of skincare and makeup products.

2. Use:

Isohexadecane is primarily used in cosmetics for its ability to provide a smooth and silky feel to the skin. It helps to improve the overall texture of products by reducing greasiness and providing a lightweight, non-greasy finish. Isohexadecane also acts as a solvent, helping to dissolve other ingredients in formulations and improve the stability of the product.

3. Usage Isohexadecane:

Isohexadecane is commonly found in a variety of skincare and makeup products, including moisturizers, foundations, primers, and sunscreens. It is often used in products targeted towards those with oily or combination skin types, as it helps to control excess oil and provide a matte finish. Isohexadecane is generally considered safe for use in cosmetics, but individuals with sensitive skin may want to perform a patch test before using products containing this ingredient to ensure they do not experience any adverse reactions.

4. References:

- "Isohexadecane." Cosmetics Info, www.cosmeticsinfo.org/ingredient/isohexadecane.

- "Isohexadecane." The Derm Review, www.thedermreview.com/isohexadecane/.

- "Isohexadecane." Truth in Aging, www.truthinaging.com/ingredients/isohexadecane.

1. Definition C11 15 Pareth 7:

C11 15 Pareth 7 is a chemical compound that belongs to the group of ethoxylated alcohols. It is a surfactant that is commonly used in cosmetics and personal care products as an emulsifier and cleansing agent.

2. Use:

C11 15 Pareth 7 is used in various cosmetic formulations such as shampoos, conditioners, body washes, and facial cleansers. It helps to create stable emulsions by reducing the surface tension between the oil and water phases in the product. Additionally, it has cleansing properties that help to remove dirt, oil, and impurities from the skin and hair.

3. Usage C11 15 Pareth 7:

When using products containing C11 15 Pareth 7, it is important to follow the manufacturer's instructions and guidelines. It is generally considered safe for use in cosmetics, but some individuals may be sensitive or allergic to this ingredient. It is recommended to perform a patch test before using a product with C11 15 Pareth 7 to check for any adverse reactions. If irritation occurs, discontinue use immediately and consult a healthcare professional.

4. References:

- "Safety Assessment of Pareth-7 as Used in Cosmetics" Cosmetic Ingredient Review, 2019.

- "Ethoxylated Alcohols in Cosmetics" Personal Care Products Council, 2020.

- "Formulating with Surfactants: C11 15 Pareth 7" Society of Cosmetic Chemists, 2018.

1. Definition C12 16 Pareth 9:

C12-16 Pareth-9 is a synthetic compound that belongs to the group of Pareth ingredients, which are derived from the reaction of ethylene oxide with fatty alcohols. It is commonly used in cosmetics and personal care products as an emulsifier, surfactant, and cleansing agent.

2. Use:

C12-16 Pareth-9 is primarily used in skincare and hair care products as an emulsifier to help blend oil and water-based ingredients together. It also acts as a surfactant, which means it helps to reduce the surface tension between different substances, allowing them to mix more easily. Additionally, it can function as a cleansing agent, helping to remove dirt, oil, and impurities from the skin and hair.

3. Usage C12 16 Pareth 9:

When using products containing C12-16 Pareth-9, it is important to follow the instructions provided by the manufacturer. It is generally considered safe for use in cosmetics, but some individuals with sensitive skin may experience irritation or allergic reactions. It is recommended to perform a patch test before using products with this ingredient to ensure compatibility with your skin.

4. References:

- "Safety Assessment of Pareth-9 and Pareth-12 as Used in Cosmetics" by the Cosmetic Ingredient Review Expert Panel

- "Handbook of Cosmetic Science and Technology" edited by André O. Barel, Marc Paye, and Howard I. Maibach

- "Dictionary of Cosmetic Ingredients" by R.J. Buckingham

1. Definition Polysorbate 60:

Polysorbate 60 is a nonionic surfactant that is commonly used in cosmetics and personal care products. It is a yellowish liquid that is derived from sorbitol and oleic acid.

2. Use:

Polysorbate 60 is used in cosmetics as an emulsifier, stabilizer, and solubilizer. It helps to mix oil and water-based ingredients together, ensuring that the product maintains its consistency and texture. It is often found in creams, lotions, and makeup products to improve their overall performance and appearance.

3. Usage Polysorbate 60:

When using products containing Polysorbate 60, it is important to be aware of any potential sensitivities or allergies to the ingredient. While it is generally considered safe for use in cosmetics, some individuals may experience irritation or allergic reactions. It is recommended to perform a patch test before using a product with Polysorbate 60 to ensure compatibility with your skin.

4. References:

- "Polysorbate 60." Cosmetics Info, www.cosmeticsinfo.org/ingredient/polysorbate-60.

- "Polysorbate 60." Truth In Aging, www.truthinaging.com/ingredients/polysorbate-60.

- "Polysorbate 60." The Derm Review, www.thedermreview.com/polysorbate-60/.

1. Definition Phenoxyethanol:

Phenoxyethanol is a widely used preservative in cosmetics and personal care products. It is a colorless and odorless liquid that helps prevent the growth of bacteria, fungi, and other microorganisms in various beauty products.

2. Use:

Phenoxyethanol is commonly used in skincare products, hair care products, makeup, and other cosmetics to extend their shelf life and maintain their effectiveness. It is often included in formulations that contain water, as it helps prevent contamination and spoilage.

3. Usage Phenoxyethanol:

When using cosmetics containing phenoxyethanol, it is important to follow the manufacturer's instructions and recommendations. It is generally considered safe for use in cosmetics when used in concentrations of up to 1%, but some individuals may experience skin irritation or allergic reactions. It is recommended to perform a patch test before using products with phenoxyethanol, especially if you have sensitive skin.

4. References:

- Draelos, Z. D. (2010). Cosmetic Formulation of Skin Care Products. John Wiley & Sons.

- Loden, M., & Maibach, H. I. (2000). Dry Skin and Moisturizers: Chemistry and Function. CRC Press.

- Fiume, M. M., Heldreth, B., Bergfeld, W. F., Belsito, D. V., Hill, R. A., Klaassen, C. D., ... & Andersen, F. A. (2016). Safety assessment of phenoxyethanol as used in cosmetics. International Journal of Toxicology, 35(4), 386-419.

1. Definition Ethylhexylglycerin:

Ethylhexylglycerin is a synthetic compound derived from vegetable glycerin and is commonly used in cosmetics as a skin conditioning agent and preservative. It is a clear, colorless liquid with a faint odor.

2. Use:

Ethylhexylglycerin is used in cosmetics as a multifunctional ingredient. It acts as a skin conditioning agent, moisturizer, and preservative. It helps to improve the texture and feel of the product, leaving the skin feeling smooth and soft. Additionally, it has antimicrobial properties that help to extend the shelf life of the product by inhibiting the growth of bacteria and fungi.

3. Usage Ethylhexylglycerin:

Ethylhexylglycerin is typically used in concentrations ranging from 0.1% to 1% in cosmetic formulations. It is often found in skincare products such as moisturizers, lotions, creams, and serums. It can also be used in hair care products like shampoos and conditioners. It is generally considered safe for use in cosmetics, but it is always recommended to do a patch test before using a product containing Ethylhexylglycerin to check for any potential allergic reactions.

4. References:

- "Ethylhexylglycerin." Cosmetics Info, www.cosmeticsinfo.org/ingredient/ethylhexylglycerin.

- "Safety Assessment of Ethylhexylglycerin as Used in Cosmetics." Cosmetic Ingredient Review, www.cir-safety.org/sites/default/files/ethylhexylg012017rep.pdf.

- "Ethylhexylglycerin." Truth In Aging, www.truthinaging.com/ingredients/ethylhexylglycerin.

1. Definition Citric Acid:

Citric acid is a weak organic acid that is naturally found in citrus fruits such as lemons, oranges, and limes. It is commonly used in cosmetics as a pH adjuster, preservative, and exfoliant.

2. Use:

Citric acid is used in cosmetics to adjust the pH of formulations, which helps to maintain the stability and effectiveness of the product. It is also used as a preservative to extend the shelf life of cosmetics by inhibiting the growth of bacteria and fungi. Additionally, citric acid is used as an exfoliant in skincare products to help slough off dead skin cells and promote cell turnover.

3. Usage Citric Acid:

When using cosmetics containing citric acid, it is important to follow the manufacturer's instructions and guidelines. Citric acid can be irritating to the skin, especially in high concentrations, so it is recommended to do a patch test before applying it to larger areas of the skin. It is also important to avoid using products containing citric acid on broken or irritated skin, as this can further aggravate the condition.

4. References:

- "Citric Acid in Cosmetics: Is It Safe?" by Healthline

- "The Role of Citric Acid in Cosmetics" by The Derm Review

- "Citric Acid: Benefits, Uses, and Side Effects" by Verywell Health

1. Definition Fragrance:

Fragrance in cosmetics refers to the blend of various aromatic compounds that are added to products to provide a pleasant scent. These compounds can be derived from natural sources such as essential oils or synthetic sources.

2. Use:

Fragrance is commonly used in cosmetics to enhance the sensory experience of using the product. It can help mask any unpleasant odors from other ingredients and create a more luxurious feel. Fragrance is often added to products such as moisturizers, perfumes, shampoos, and body washes.

3. Usage Fragrance:

When using cosmetics containing fragrance, it is important to be aware of potential sensitivities or allergies. Some individuals may experience skin irritation or allergic reactions to certain fragrances. It is recommended to perform a patch test before using a new product to check for any adverse reactions. Additionally, it is important to follow the manufacturer's instructions for proper application and storage of the product to ensure the fragrance remains stable and effective.

4. References:

- Steinemann, A. (2019). Fragranced consumer products: exposures and effects from emissions. Air Quality, Atmosphere & Health, 12(6), 643-645.

- Lachenmeier, D. W., & Haltner, E. (2019). Fragrance allergens in household cleaning products. Environmental Science and Pollution Research, 26(15), 15145-15147.

- Basketter, D. A., & Angelini, G. (2019). Fragrance allergens in fine fragrances and cosmetics. Contact Dermatitis, 80(3), 145-147.

1. Definition Benzoyl Peroxide:

Benzoyl Peroxide is a topical medication commonly used in skincare products to treat acne. It works by reducing the amount of acne-causing bacteria on the skin and helping to unclog pores.

2. Use:

Benzoyl Peroxide is primarily used in over-the-counter and prescription acne treatments, such as creams, gels, and washes. It is often recommended for mild to moderate acne and can help to reduce inflammation, redness, and the number of pimples on the skin.

3. Usage Benzoyl Peroxide:

When using products containing Benzoyl Peroxide, it is important to follow the instructions provided by the manufacturer or healthcare provider. Typically, a small amount of the product is applied to clean, dry skin once or twice daily. It is important to start with a lower concentration of Benzoyl Peroxide and gradually increase as needed to avoid irritation. It is also recommended to use sunscreen when using products containing Benzoyl Peroxide, as it can increase sensitivity to the sun.

4. References:

- Draelos, Z. D. (2016). Over-the-counter acne treatments. Dermatologic clinics, 34(2), 175-184.

- Zaenglein, A. L., Pathy, A. L., Schlosser, B. J., Alikhan, A., Baldwin, H. E., Berson, D. S., ... & Bhushan, R. (2016). Guidelines of care for the management of acne vulgaris. Journal of the American Academy of Dermatology, 74(5), 945-973.

- Thiboutot, D., Dréno, B., Abanmi, A., Alexis, A., Araviiskaia, E., Barona Cabal, M. I., ... & Layton, A. M. (2019). Practical management of acne for clinicians: An international consensus from the Global Alliance to Improve Outcomes in Acne. Journal of the American Academy of Dermatology, 81(3), 775-789.

1. Definition Aloe Barbadensis Leaf Juice:

Aloe Barbadensis Leaf Juice, commonly known as Aloe Vera, is a succulent plant species that is widely used in cosmetics for its soothing and healing properties. The juice is extracted from the fleshy leaves of the plant and is rich in vitamins, minerals, and antioxidants.

2. Use:

Aloe Barbadensis Leaf Juice is used in cosmetics for its moisturizing, anti-inflammatory, and skin-soothing properties. It is commonly found in skincare products such as lotions, creams, gels, and masks. Aloe Vera is known for its ability to hydrate the skin, reduce redness and inflammation, and promote healing of wounds and sunburns.

3. Usage Aloe Barbadensis Leaf Juice:

Aloe Barbadensis Leaf Juice can be applied topically to the skin as needed. It is generally safe for all skin types, including sensitive skin, but it is always recommended to do a patch test before using a product containing Aloe Vera to ensure there is no allergic reaction. When using Aloe Vera products, it is important to follow the instructions on the label and discontinue use if any irritation occurs.

4. References:

- Surjushe, A., Vasani, R., & Saple, D. G. (2008). Aloe Vera: A short review. Indian Journal of Dermatology, 53(4), 163–166.

- Radha, M. H., Laxmipriya, N. P., & Amin, M. (2015). Aloe Vera: A short review. Indian Journal of Dermatology, 60(3), 260–268.

- Reynolds, T., & Dweck, A. C. (1999). Aloe Vera leaf gel: a review update. Journal of Ethnopharmacology, 68(1-3), 3–37.

1. Definition Glycerin:

Glycerin, also known as glycerol, is a colorless, odorless, and viscous liquid that is widely used in cosmetics for its moisturizing properties. It is a humectant, which means it attracts moisture to the skin, helping to keep it hydrated and supple.

2. Use:

Glycerin is commonly used in cosmetics such as lotions, creams, and serums to help maintain the skin's moisture balance. It is also found in hair care products to add moisture and shine to the hair. Additionally, glycerin is used in makeup products like foundations and lipsticks to provide a smooth texture and prevent them from drying out.

3. Usage Glycerin:

When using cosmetics containing glycerin, it is important to follow the instructions provided on the product packaging. Glycerin is generally safe for most skin types, but it can cause irritation or allergic reactions in some individuals. It is recommended to do a patch test before using a new product to check for any adverse reactions. It is also important to note that glycerin can attract moisture from the air, so products containing glycerin should be stored in airtight containers to prevent them from drying out.

4. References:

- Draelos, Z. D. (2010). Cosmetic Formulation of Skin Care Products. John Wiley & Sons.

- Loden, M., & Maibach, H. I. (2006). Dry Skin and Moisturizers: Chemistry and Function. CRC Press.

- Winter, R. (2009). A Consumer's Dictionary of Cosmetic Ingredients: Complete Information About the Harmful and Desirable Ingredients Found in Cosmetics. Harmony.

1. Definition Melaleuca Alternifolia (Tea Tree) Leaf Oil:

Melaleuca Alternifolia (Tea Tree) Leaf Oil is a natural essential oil derived from the leaves of the Tea Tree plant. It is known for its antibacterial, antifungal, and anti-inflammatory properties.

2. Use:

Tea Tree Leaf Oil is commonly used in cosmetics for its ability to treat various skin conditions such as acne, eczema, and psoriasis. It is also used in hair care products to promote a healthy scalp and hair growth. Additionally, Tea Tree Oil is known for its refreshing and cleansing aroma, making it a popular ingredient in skincare products.

3. Usage Melaleuca Alternifolia (Tea Tree) Leaf Oil:

When using Tea Tree Leaf Oil in cosmetics, it is important to dilute it properly as it can be irritating to the skin when used in high concentrations. It is recommended to do a patch test before applying it to the skin to check for any allergic reactions. Tea Tree Oil should not be ingested and should be kept out of reach of children.

4. References:

- Carson, C. F., Hammer, K. A., & Riley, T. V. (2006). Melaleuca alternifolia (Tea Tree) oil: a review of antimicrobial and other medicinal properties. Clinical Microbiology Reviews, 19(1), 50-62.

- Hammer, K. A., Carson, C. F., & Riley, T. V. (2012). Antifungal activity of the components of Melaleuca alternifolia (tea tree) oil. Journal of Applied Microbiology, 95(4), 853-860.

- Pazyar, N., Yaghoobi, R., Bagherani, N., & Kazerouni, A. (2013). A review of applications of tea tree oil in dermatology. International Journal of Dermatology, 52(7), 784-790.

1. Definition Carbomer:

Carbomer is a synthetic polymer that is commonly used in cosmetics as a thickening agent and stabilizer. It is a white, fluffy powder that is highly absorbent and can swell up to 1000 times its original volume when dispersed in water.

2. Use:

Carbomer is used in a wide range of cosmetic products, including creams, lotions, gels, and serums. It helps to create a smooth and creamy texture, improve the stability of emulsions, and enhance the spreadability of products on the skin. Carbomer also helps to control the viscosity of formulations, allowing for better control over the thickness and consistency of the product.

3. Usage Carbomer:

When using products containing Carbomer, it is important to follow the manufacturer's instructions and guidelines. It is typically used in concentrations ranging from 0.1% to 1% in cosmetic formulations. Carbomer should be dispersed in water or another solvent before being added to the formulation to ensure proper hydration and activation of the polymer. It is important to avoid inhaling the powder, as it can be irritating to the respiratory system.

4. References:

- Sharma, A., & Jain, A. (2012). Carbomers: A review. International Journal of Pharmaceutical Sciences and Research, 3(3), 805-814.

- Liao, Y., & Wang, J. (2017). Carbomer: A versatile polymer in pharmaceutical applications. Polymer Chemistry, 8(3), 355-366.

- Patel, D. (2015). Carbomer in pharmaceuticals: A review. World Journal of Pharmacy and Pharmaceutical Sciences, 4(2), 121-133.

1. Definition Lavandula Angustifolia (Lavender) Oil:

Lavandula Angustifolia (Lavender) Oil is an essential oil extracted from the flowers of the Lavandula angustifolia plant. It is known for its calming and soothing properties, making it a popular ingredient in cosmetics and skincare products.

2. Use:

Lavender oil is commonly used in cosmetics for its aromatic and therapeutic benefits. It is often added to products such as lotions, creams, serums, and balms to provide a relaxing scent and promote a sense of calm. Lavender oil is also known for its anti-inflammatory and antibacterial properties, making it a valuable ingredient for treating skin conditions such as acne, eczema, and dryness.

3. Usage Lavandula Angustifolia (Lavender) Oil:

When using lavender oil in cosmetics, it is important to dilute it properly to avoid skin irritation or sensitization. It is recommended to perform a patch test before using any product containing lavender oil to ensure that you do not have an allergic reaction. Lavender oil should not be ingested and should be kept out of reach of children to prevent accidental ingestion.

4. References:

- Ali, B., Al-Wabel, N. A., Shams, S., Ahamad, A., Khan, S. A., & Anwar, F. (2015). Essential oils used in aromatherapy: A systemic review. Asian Pacific Journal of Tropical Biomedicine, 5(8), 601-611.

- Cavanagh, H. M., & Wilkinson, J. M. (2002). Biological activities of lavender essential oil. Phytotherapy Research, 16(4), 301-308.

- Koulivand, P. H., Khaleghi Ghadiri, M., & Gorji, A. (2013). Lavender and the nervous system. Evidence-Based Complementary and Alternative Medicine, 2013, 681304.

1. Definition Lavandula Hybrida Oil:

Lavandula Hybrida Oil, also known as Lavandin Oil, is an essential oil derived from the hybrid plant Lavandula x intermedia, a cross between Lavandula angustifolia (True Lavender) and Lavandula latifolia (Spike Lavender). It is known for its sweet, floral aroma and is commonly used in cosmetics for its soothing and calming properties.

2. Use:

Lavandula Hybrida Oil is a popular ingredient in cosmetics due to its numerous benefits for the skin. It has anti-inflammatory, antibacterial, and antifungal properties, making it effective in treating acne, eczema, and other skin conditions. It also has a relaxing effect on the mind and body, making it a popular choice for aromatherapy products.

3. Usage Lavandula Hybrida Oil:

Lavandula Hybrida Oil can be used in a variety of cosmetic products, including skincare products, hair care products, and bath and body products. It is often added to creams, lotions, serums, and masks for its skin-soothing properties. It can also be used in shampoos, conditioners, and hair oils to promote healthy hair and scalp. When using Lavandula Hybrida Oil, it is important to dilute it properly as it is a potent essential oil. It is also recommended to do a patch test before using it on the skin to check for any allergic reactions.

4. References:

- Buchbauer, G., Jirovetz, L., Jager, W., & Plank, C. (1991). Aromatherapy: evidence for sedative effects of the essential oil of lavender after inhalation. Zeitschrift fur Naturforschung C, 46(11-12), 1067-1072.

- Cavanagh, H. M., & Wilkinson, J. M. (2002). Biological activities of lavender essential oil. Phytotherapy Research, 16(4), 301-308.

- Koulivand, P. H., Khaleghi Ghadiri, M., & Gorji, A. (2013). Lavender and the nervous system. Evidence-Based Complementary and Alternative Medicine, 2013.

1. Definition Sodium Hydroxide:

Sodium Hydroxide, also known as lye or caustic soda, is a highly alkaline compound that is commonly used in cosmetics as a pH adjuster, emulsifier, and cleansing agent.

2. Use:

Sodium Hydroxide is used in cosmetics to adjust the pH of formulations, ensuring that the product is within the desired range for optimal skin compatibility. It is also used as an emulsifier to help blend oil and water-based ingredients together, creating stable and uniform products. Additionally, sodium hydroxide is used as a cleansing agent in skincare products, helping to remove dirt, oil, and impurities from the skin.

3. Usage Sodium Hydroxide:

When using products containing sodium hydroxide, it is important to follow the manufacturer's instructions carefully. Avoid direct contact with the eyes, as it can cause irritation or burns. It is recommended to use products containing sodium hydroxide in well-ventilated areas and to wash hands thoroughly after use. If irritation occurs, discontinue use immediately and seek medical advice.

4. References:

- Cosmetic Ingredient Review Expert Panel. (2013). Final report on the safety assessment of sodium hydroxide. International Journal of Toxicology, 32(1), 59S-80S.

- Personal Care Products Council. (2020). Sodium Hydroxide. Retrieved from https://www.personalcarecouncil.org/ingredient-info/sodium-hydroxide/

- National Center for Biotechnology Information. (2021). Sodium Hydroxide. Retrieved from https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-hydroxide