Sodium lauroyl sarcosinate (sodium N-dodecanoyl-sarcosinate)is a chemical compound, amphiphilic, N-acyl derivative of sarcosine and is used as a surfactant in personal care products for its effective yet gentle cleansing properties. It is valued for its ability to produce foam and for being less irritating compared to other more aggressive surfactants.

The name describes the structure of the molecule:

• Sodium indicates the presence of sodium, a chemical element. In the context of surfactants, sodium is used to form salts with organic compounds.
• Lauroyl refers to lauric acid, a fatty acid. Lauroyl in this context indicates that the compound is a derivative of lauric acid.
• Sarcosinate, a functional group derived from sarcosine, an amino acid. Sarcosinates are known for their gentle cleansing and foaming properties.

Raw Materials and Their Functions

Lauric Acid. A fatty acid used as the base for the production of sodium lauroyl sarcosinate. It provides the detergent and foaming properties of the compound.

Sarcosine. A derivative of the amino acid glycine, used to react with lauric acid to form sarcosinate.

Sodium. Used to neutralize the mixture and form the sodium salt of the sarcosinate.

Industrial Chemical Synthesis of Sodium Lauroyl Sarcosinate

• Esterification Reaction of lauric acid with sarcosine. During this reaction, lauroyl sarcosinate is formed.
• Neutralization with Sodium. After the formation of sarcosinate, sodium is added to neutralize the compound and form sodium lauroyl sarcosinate.
• Reaction Control. The esterification reaction and neutralization are monitored to ensure the final product has the desired properties.
• Purification. The compound is purified to remove impurities and by-products.
• Quality Control. The purified sodium lauroyl sarcosinate undergoes quality checks to ensure it meets the required standards. After quality control, it is packaged for use in personal care products, where it utilizes its properties as a mild and effective surfactant.

It occurs as a colourless to slightly straw-coloured liquid, as a 30% aqueous solution or as an anhydrous white powder with 97% purity.

What it is used for and where it is used

It has some interesting characteristics (1) such as stability and biodegradability, biocidal action on microorganisms, high surface activity over a wide range as the surfactant is present in the surface phase in a significantly higher concentration than in the bulk phase. It is very stable with hard water with salt water and with various detergent and cosmetic products in the presence of water-hardening materials (2). In flotation treatment, it has a good synergistic effect with cationic surfactants to achieve higher flotation efficiency.

Compared to Sodium Lauryl Sulfate (SLS) and Sodium Laureth sulfate (SLES), the two most popular low-cost surfactants, it is less irritating and non-genotoxic. In fact, SLS is rather aggressive on the skin and, over the years, numerous allergies have been detected, while SLES, a derivative of SLS, not infrequently contains chemical compounds that are considered carcinogenic in the scientific literature. The option Sodium lauroyl sarcosinate as first surfactant is correct. Cocamidopropyl betaine, another chemical compound considered safe, is usually proposed as the second surfactant.

Cosmetics 

Sodium lauroyl sarcosinate is an anionic surfactant (removes dirt particles) and therefore also an efficient oil emulsifier, used in cosmetics in liquid soaps, toothpastes and more. It also has strong anti-corrosive properties. It acts as a conditioning agent for hair and as a detergent with high foaming power.

INCI functions:

Antistatic agent. Static electricity build-up has a direct influence on products and causes electrostatic adsorption. The antistatic ingredient reduces static build-up and surface resistivity on the surface of the skin and hair.

Cleansing agent. Ingredient that cleanses skin without exploiting the surface-active properties that produce a lowering of the surface tension of the stratum corneum. 

Surfactant - Emulsifying agent. Emulsions are thermodynamically unstable and are used to soothe or soften the skin and emulsify, so they need a specific, stabilising ingredient. This ingredient forms a film, lowers the surface tension and makes two immiscible liquids miscible. A very important factor affecting the stability of the emulsion is the amount of the emulsifying agent. Emulsifiers have the property of reducing the oil/water or water/oil interfacial tension, improving the stability of the emulsion and also directly influencing the stability, sensory properties and surface tension of sunscreens by modulating the filmometric performance.

Foaming.  Its function is to introduce gas bubbles into the water for a purely aesthetic factor, which does not affect the cleaning process, but only satisfies the commercial aspect of the detergent by helping to spread the detergent. This helps in the commercial success of a cleansing formulation. Since sebum has an inhibiting action on the bubble, more foam is produced in the second shampoo. In practice, it creates many small bubbles of air or other gases within a small volume of liquid, changing the surface tension of the liquid.

Hair conditioning agent. A significant number of ingredients with specific and targeted purposes may co-exist in hair shampoo formulations: cleansers, conditioners, thickeners, matting agents, sequestering agents, fragrances, preservatives, special additives. However, the indispensable ingredients are the cleansers and conditioners as they are necessary and sufficient for hair cleansing and manageability. The others act as commercial and non-essential auxiliaries such as: appearance, fragrance, colouring, etc. Hair conditioning agents have the task of increasing shine, manageability and volume, and reducing static electricity, especially after treatments such as colouring, ironing, waving, drying and brushing. They are, in practice, dispersants that may contain cationic surfactants, thickeners, emollients, polymers. The typology of hair conditioning agents includes: intensive conditioners, instant conditioners, thickening conditioners, drying conditioners. They can perform their task generally accompanied by other different ingredients.

Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

Surfactant - Cleansing agent. Cosmetic products used to cleanse the skin utilise the surface-active action that produces a lowering of the surface tension of the stratum corneum, facilitating the removal of dirt and impurities. 

Viscosity control agent. It controls and adapts, Increasing or decreasing, viscosity to the required level for optimal chemical and physical stability of the product and dosage in gels, suspensions, emulsions, solutions. 

Dertergents

Abstract.This safety assessment addresses cosmetic ingredients that are N-acyl derivatives of sarcosine and are generally referred to as acyl sarcosines, and those that are salts, known generally as acyl sarcosinates. Previous assessments have addressed the safety of each of the fatty acids that appear in these acyl sarcosines and sarcosinates (Coconut Acid, Oleic Acid, Lauric Acid, and Myristic Acid). In each case the fatty acid was either safe for use or safe as used in cosmetic formulations. Acyl sarcosines are considered modified fatty acids with greater solubility and increased acidity of the carboxylic acid group compared to the parent fatty acid. They are used in a large number of cosmetic formulations as hair-conditioning agents and surfactant-cleansing agents. In soaps, concentrations are reported to be as high as 12.9%. These ingredients have low oral toxicity in rats. Although cytotoxic to Chinese hamster cells in culture, acyl sarcosines and sarcosinates are not mutagenic in those cells, nor in bacterial cells in culture. Carcinogenicity data were not available. These ingredients are nonirritating and nonsensitizing to animal and human skin, although they can enhance the penetration of other ingredients through the skin. For that reason, caution should be exhibited in formulating cosmetic products that contain these ingredients in combination with other ingredients whose safety is based on their lack of absorption or where dermal absorption is a concern (e.g., HC Yellow No. 4, Disperse Yellow 3). Because sarcosine can be nitrosated to form N-nitrososarcosine, a known animal carcinogen, these ingredients should not be used in cosmetic products in which N-nitroso compounds may be formed. With the above caveat, and based on the available data, it was concluded that these acyl sarcosines and sarcosinates are safe as used in rinse-off products. They may be safely used in leave-on products at concentrations up to 5%, the highest concentration tested in clinical irritation and sensitization studies. Oleoyl Sarcosine is used as a corrosion inhibitor in some aerosol products, at extremely low concentrations. In this circumstance, the ingredient is not being used as a cosmetic ingredient and this report is not intended to limit that use. Because of the absence of data on inhalation toxicity, however, it was concluded that the available data were not sufficient to support the safety of acyl sarcosines and sarcosinates as cosmetic ingredients in products where they are likely to be inhaled. (3).

Medicine

In vitro real-time PCR for counting Escherichia coli (4).

Frequently used for solubilisation of inclusion bodies in vitro due to its structural similarity to the plasma lipid membrane (5).

Disinfection of aquatic environments

The results of this study indicate that an optimal combination of propidium monoazide/sodium lauroyl sarcosinate could be very useful for evaluating disinfection methods in water treatment strategies (6).

Sodium lauroyl sarcosinate studies

Typical optimal characteristics of the liquid commercial product N-Lauroylsarcosine sodium salt

Appearance	Colourless to slightly straw-coloured liquid or white powder
Boiling Point	100°C
Melting Point	46°C
Flash Point
PSA	60.44000
LogP	2.11560
Water Solubility	1 M at 20 °C
pH 10%aq.solution@25℃	7.5-8.5
NaCl /KCl(%)	0.2Max
Sodium laurate, %	Sodium laurate, %
Bacterial count, CFU/ml	100max
Molds & yeasts, CFU/mL	100max
Pb, ppm	10max
As, ppm	2max
Safety

• Molecular Formula : C₁₅H₂₈NO₃.Na    C₁₅H₂₈NNaO₃   C₁₅H₂₈NO₃ · Na
• Linear Formula   CH₃(CH₂)₁₀CON(CH₃)CH₂COONa
• Molecular Weight : 293.38
• Exact Mass   293.196686
• CAS : 137-16-6
• UNII 632GS99618
• EC Number 205-281-5
• DSSTox Substance ID DTXSID0027066
• IUPAC  sodium;2-[dodecanoyl(methyl)amino]acetate
• InChI=1S/C15H29NO3.Na/c1-3-4-5-6-7-8-9-10-11-12-14(17)16(2)13-15(18)19;/h3-13H2,1-2H3,(H,18,19);/q;+1/p-1
• InChl Key      KSAVQLQVUXSOCR-UHFFFAOYSA-M
• SMILES CCCCCCCCCCCC(=O)N(C)CC(=O)[O-].[Na+]
• MDL number  MFCD00042728
• PubChem Substance ID 24896478
• Beilstein   5322974
• NACRES   NA.25

Synonyms :

• Sarkosyl NL
• N-Lauroylsarcosine sodium salt solution
• Sodium lauroylsarcosinate
• N-dodecanoyl-N-methylglycine
• sodium;2-[dodecanoyl(methyl)amino]acetate
• N-methyl-N-(1-oxododecyl)glycine sodium salt (1:1)

References________________________________________________

(1) Sułek MW, Bąk-Sowińska A, Przepiórka J. Ecological Cutting Fluids. Materials (Basel). 2020 Dec 19;13(24):5812. doi: 10.3390/ma13245812.

(2) Patra N, Ray D, Aswal VK, Ghosh S. Exploring Physicochemical Interactions of Different Salts with Sodium N-Dodecanoyl Sarcosinate in Aqueous Solution. ACS Omega. 2018 Aug 16;3(8):9256-9266. doi: 10.1021/acsomega.8b00718. 

(3) Final report on the safety assessment of Cocoyl Sarcosine, Lauroyl Sarcosine, Myristoyl Sarcosine, Oleoyl Sarcosine, Stearoyl Sarcosine, Sodium Cocoyl Sarcosinate, Sodium Lauroyl Sarcosinate, Sodium Myristoyl Sarcosinate, Ammonium Cocoyl Sarcosinate, and Ammonium Lauroyl Sarcosinate.  Lanigan RS.  Int J Toxicol. 2001;20 Suppl 1:1-14. Review.

(4) Wang H, Gill CO, Yang X. Use of sodium lauroyl sarcosinate (sarkosyl) in viable real-time PCR for enumeration of Escherichia coli. J Microbiol Methods. 2014 Mar;98:89-93. doi: 10.1016/j.mimet.2014.01.004. 

(5)  Alsenaidy MA. Aggregation and conformational stability evaluation of myoglobin in the presence of ionic surfactant. Saudi Pharm J. 2018 May;26(4):515-519. doi: 10.1016/j.jsps.2018.02.005. 

(6) Lee HW, Lee HM, Yoon SR, Kim SH, Ha JH. Pretreatment with propidium monoazide/sodium lauroyl sarcosinate improves discrimination of infectious waterborne virus by RT-qPCR combined with magnetic separation. Environ Pollut. 2018 Feb;233:306-314. doi: 10.1016/j.envpol.2017.10.081.