Benzalkonium chloride
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| Benzalkonium chloride | |
|---|---|
 |
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| Molar mass | (mixture) |
| CAS number | [8001-54-5] |
| EINECS number | |
| Properties | |
| Density | 0.98 |
| Solubility in water | very soluble |
| Hazards | |
| EU classification | C, N [1] |
| NFPA 704 |
 0
1
0
|
| R-phrases | R21/22, R34, R50 [1] |
| S-phrases | S36/37/39, S45, S61 [1] |
| Flash point | 250 °C |
| RTECS number | BO3150000 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Benzalkonium chloride (alkyldimethylbenzylammonium chloride) is a mixture of alkylbenzyldimethylammonium chlorides of various even-numbered[2] alkyl chain lengths. This product is a nitrogenous cationic surface-acting agent belonging to the quaternary ammonium group. It has three main categories of use; as a biocide, a cationic surfactant and phase transfer agent in the chemical industry.
Contents |
[edit] Properties
Benzalkonium chloride is readily soluble in ethanol, and acetone. Although dissolution in water is slow, aqueous solutions are easier to handle and are preferred. Solutions should be neutral to slightly alkaline, with colour ranging from clear to a pale yellow. Solutions foam profusely when shaken, have a bitter taste and a faint almond-like odour which is only detectable in concentrated solutions.
[edit] Availability
Standard concentrates are manufactured as 50% and 80% w/w solutions, and sold under trade names such as BC50, BC80, BAC50, BAC80, etc. The 50% solution is purely aqueous, while more concentrated solutions require incorporation of rheology modifiers (alcohols, polyethylene glycols, etc.) to prevent increases in viscosity or gel formation under low temperature conditions.
[edit] Applications
Applications are extremely wide ranging[3], from disinfectant formulations to microbial corrosion inhibition in the oilfield sector. It has been considered one of the safest synthetic biocides known and has a long history of efficacious use. It is currently used in human pharmaceuticals such as leave-on skin antiseptics, hygienic towelettes, and wet wipes. Ethanol-free benzalkonium solutions are often used for skin disinfection prior to withdrawing blood for blood alcohol content tests. Its use as a preservative in cosmetics such as eye and nasal drops attest to its general safety; however, there have been reports of allergy associated with continuous, long-term use in sensitive users, especially on mucous membranes.
[edit] Biological activity
The greatest biocidal activity is associated with the C12-C14 alkyl derivatives. The mechanism of bactericidal/microbicidal action is thought to be due to disruption of intermolecular interactions. This can cause dissociation of cellular membrane bilayers, which compromises cellular permeability controls and induces leakage of cellular contents. Other biomolecular complexes within the bacterial cell can also undergo dissociation. Enzymes, which finely control a plethora of respiratory and metabolic cellular activities, are particularly susceptible to deactivation. Critical intermolecular interactions and tertiary structures in such highly specific biochemical systems can be readily disrupted by cationic surfactants.
Benzalkonium chloride solutions are rapidly acting biocidal agents with a moderately long duration of action. They are active against bacteria and some viruses, fungi, and protozoa. Bacterial spores are considered to be resistant. Solutions are bacteriostatic or bactericidal according to their concentration. Gram-positive bacteria are generally more susceptible than Gram-negative. Activity is not greatly affected by pH, but increases substantially at higher temperatures and prolonged exposure times.
Newer formulations using benzalkonium blended with various quaternary ammonium derivatives can be used to extend the biocidal spectrum and enhance the efficacy of benzalkonium based disinfection products. This technique has been used to improve virucidal activity of quaternary ammonium-based formulations to healthcare infection hazards such as hepatitis, HIV, etc. Quaternary ammonium formulations are now the disinfectants of choice for hospitals. This is on account of user and patient safety even on contact with treated surfaces and the absence of harmful fumes. Benzalkonium solutions for hospital use tend to be neutral to alkaline, non-corrosive on metal surfaces, non-staining and safe to use on all washable surfaces.
The use of appropriate supporting excipients can also greatly improve efficacy and detergency, and prevent deactivation under use conditions. Formulation requires great care as Benzalkonium solutions can be readily inactivated in the presence of organic and inorganic contamination. Solutions are incompatible with soaps, and must not be mixed with anionic surfactants. Hard water salts can also reduce biocidal activity. As with any disinfectant, it is recommended that surfaces are free from visible dirt and interfering materials for maximal disinfection performance by quaternary ammonium products.
Although hazardous levels are not likely to be reached under normal use conditions, it is important to remember that benzalkonium and other detergents can pose a hazard to marine organisms. Quaternary ammonium disinfectants are effective at very low ppm levels, so it is important avoid excess in use. Responsible care ensures that we do not disrupt the fragile marine ecosystems that sustain us.
[edit] Safety
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Please help improve this article or section by expanding it. Further information might be found on the talk page or at requests for expansion. (February 2007) |
Benzalkonium chloride is an allergen[4][5][6][7][8][9][10] and several studies have cast doubt on its reputation for safety.[11][12]
Some products have been reformulated in light of this research, but it is still widely used in eyewashes, hand and face washes, mouthwashes, spermicidal creams, and in various other cleaners, sanitizers, and disinfectants. Manufacturers of over-the-counter artificial tears and eye washes became concerned about chemical sensitivity from long-term daily use and have in some products substituted EDTA as a preservative. Some have added "for sensitive eyes" to labeling. There has also been concern that long-term use of benzalkonium as a preservative in nose sprays may cause swelling of mucosa and lead to Rhinitis medicamentosa. Some manufacturers have put 3-day limits on safe use of such nose sprays.
[edit] References
- ^ a b c Record of Quaternary ammonium compounds, benzyl-C8–18-alkyldimethyl, chlorides in the European chemical Substances Information System ESIS
- ^ US EPA: Reregistration Eligibility Decision for Alkyl Dimethyl Benzyl Ammonium Chloride (ADBAC)
- ^ quatchem.co.uk
- ^ Park HJ, Kang HA, Lee JY, Kim HO (2000). "Allergic contact dermatitis from benzalkonium chloride in an antifungal solution". Contact Derm. 42 (5): 306-7. PMID 10789868.
- ^ Liu H, Routley I, Teichmann KD (2001). "Toxic endothelial cell destruction from intraocular benzalkonium chloride". J Cataract Refract Surg 27 (11): 1746-50. doi:. PMID 11709246.
- ^ Chiambaretta F, Pouliquen P, Rigal D (1997). "[Allergy and preservatives. Apropos of 3 cases of allergy to benzalkonium chloride]" (in French). J Fr Ophtalmol 20 (1): 8-16. PMID 9099278.
- ^ Wong DA, Watson AB (2001). "Allergic contact dermatitis due to benzalkonium chloride in plaster of Paris". Australas. J. Dermatol. 42 (1): 33-5. doi:. PMID 11233718.
- ^ Kanerva L, Jolanki R, Estlander T (2000). "Occupational allergic contact dermatitis from benzalkonium chloride". Contact Derm. 42 (6): 357-8. PMID 10871106.
- ^ Oiso N, Fukai K, Ishii M (2005). "Irritant contact dermatitis from benzalkonium chloride in shampoo". Contact Derm. 52 (1): 54. doi:. PMID 15701139.
- ^ Basketter DA, Marriott M, Gilmour NJ, White IR (2004). "Strong irritants masquerading as skin allergens: the case of benzalkonium chloride". Contact Derm. 50 (4): 213-7. doi:. PMID 15186375.
- ^ Graf P (2001). "Benzalkonium chloride as a preservative in nasal solutions: re-examining the data". Respir Med 95 (9): 728-33. doi:. PMID 11575893.
- ^ Marple B, Roland P, Benninger M (2004). "Safety review of benzalkonium chloride used as a preservative in intranasal solutions: an overview of conflicting data and opinions". Otolaryngol Head Neck Surg 130 (1): 131-41. doi:. PMID 14726922.
[edit] Further reading
- Bernstein IL: Is the use of benzalkonium chloride as a preservative for nasal formulations a safety concern? J Allergy Clin Immunol 2000 Jan; 105(1 Pt 1): 39-44.
- Graf P: Adverse effects of benzalkonium chloride on the nasal mucosa: allergic rhinitis and rhinitis medicamentosa. Clin Ther 1999 Oct; 21(10): 1749-55.
- Graf P, Hallen H, Juto JE: Benzalkonium chloride in a decongestant nasal spray aggravates rhinitis medicamentosa in healthy volunteers. Clin Exp Allergy 1995 May; 25(5): 395-400.
