A REVIEW ON HERBAL SURFACTANT

ABOUT AUTHORS:
Mahaveer Prasad Kabra*, Sanjay Singh Bhandari, Shakti Singh, Paresh Mohan.
Kota College of Pharmacy, SP-1,
RIICO Industrial Area, Ranpur,
Jhalawar road, Kota, Rajasthan, India – 324009
*sanskarkabra@gmail.com

ABSTRACT:
Surfactant plays an important role in various drug delivery. To formulate the compounds sparingly soluble in water the surfactants are typically employed to increase solubility. Herbal are materials which have a tendency to preferentially get absorbed at the interface between two phases. The low solubility in biological fluids displayed by about 50% of the drugs still remains the main limitation in oral, parenteral and transdermal administration. Among the strategies to overcome these drawbacks surfactant is the most effective alternative. This article review about the herbal surfactants, their types, limitation, structure and mechanism, and evaluation of herbal surfactant.

REFERENCE ID: PHARMATUTOR-ART-1771

INTRODUCTION:
A surfactant is a compound that can reduce the interfacial tension between two immiscible phases. When surfactants obtain from natural sources then they are called herbal surfactant. Herbal are materials which have a tendency to preferentially get absorbed at the interface between two phases.
This is due to the molecule containing two localised regions, one being hydrophilic in nature and the other hydrophobic. Hydrophilic part is polar in nature, while hydrophobic part is non polar in nature. Result of their surface absorption is that tension between the two phases is inevitabely lowered and phases acquired greater tendency to intermix mix each other. ^{(1, 2)}

Classification of herbal surfactant:
There are three categories of surfactants
1.    Non-ionic
2.    Anionic
3.    Cationic

1.    Non-ionic surfactant:
The properties of non-ionic surfactant are largely dependent on the proportions of these two groups in the molecule. Hydrophilic groups include the oxyethylene group (-O.CH2.CH2-) and the hydroxyl group (-OH). By varying the number of these groups in a hydrophobic molecule, such as a fatty acid, substances are obtained which range from strongly hydrophobic and water-insoluble compounds, such as glyceryl monostearate, to strongly hydrophobic and water soluble compounds, such as the macrogols. The range of non-ionic surfactant used in pharmaceutical practice is large and their classification can be varied and complex. The principal groups of non-ionic surfactants are outlined below.

Glycol and glycerol esters: These are a group of non-ionic surfactants consisting of fatty acid esters of glycols and glycerol.
Acetoglycerides: These are mixed glyceryl esters in which the glycerol is esterified partly with a fatty acid and partly with acetic acid.
Macrogol esters: These are polyoxyethylene esters of fatty acids, mainly stearates.
Macrogol ethers: These are condensation products prepared by reaction between fatty alcohols or alkylphenols and ethylene oxide.
Sorbitan derivatives: These are derivatives of the cyclic mono or di anhydrides of sorbitol.
Poloxamers: These are copolymers of polyoxyethylene and polyoxypropylene. ^{(2, 3)}

2.    Anionic surfactant:
Anionic are group of surfactants which ionise in aqueous media and whose surfactant activities related to the anionic part. The important hydrophilic group involved in the construction of anionic surfactant are carboxylic sulphate ester, sulfonic ester and phosphate ester groups and are broadly represented by the four groups are:
Soaps: Soaps may be looked upon as esters of higher fatty acids or of rosin acids with metallic salts such as Na, K, Ca, Ba, Mg, etc. or with other alkaline material such as ammonia or organic alkalies.
Alkaline metal and ammonium soap: These are the sodium, potassium or ammonium salt of long chain fatty acids, such as oleic, stearic and ricinolic. They produce o/w emulsion.
Sulphated compounds: Sulphated compounds may be looked upon as derivative of sulphuric acid in which one of the H is replaced by R group.
Eg. Sodium lauryl sulphate, Sodium cetyl sulphate.
Sulphonated compound: Sulphonated compound may be considered as derivative of sulforous acids.
eg. Dioctyl sodium sulphosuccinate, triton X-200, Dodecyl benzene sulphonate. ^{(4, 5, 6)}

3.    Cationic surfactant:
Cationic surfactants are mostly quaternary ammonium compounds. Some of them are however amino salts, amino amides or immadazolines eg. Benzalkonium chloride, Cetyl ammonium bromide, zephiran. ^{(3, 7)}

Limitation of surfactant

Name of surfactant	Side effects
Cationic surfactant	These chemicals have a positive electrical charge. They contain a quaternary ammonium group and are often called quats. They are synthetic, irritating, allergenic and toxic, and oral intake of them can be lethal.
Stearic acid	May cause irritation; health effects not adequately investigated.
Sorbitan stearate	Generally recognised as being safe; may cause contact urticaria.
Sorbitan palmitate	May cause contact dermatitis.
sorbitan oleate	May cause contact urticaria and allergic reactions.
Sorbitan monolaurate	Caused adverse reproductive effects in animals and may be a carcinogen.
Sorbitan laurate	May cause contact urticaria.
Sodium oleth sulphate	May contain dangerous levels of ethylene oxide and 1, 4-dioxane both potent.
Sodium myreth sulphate	Mild to moderate eye irritation in animal studies.
Sodium methyl cocoyl taurate	May cause formation of nitrosamines.
Sodium lauryl sulphoacetate	Mild to moderate skin irritation; slight eye irritation; slightly toxic to rats in oral doses.
Cocoamidopropyl hydroxysultaine	May cause allergic skin rash, may contain nitrosamines.
Cetyl ricinoleate	May cause eye irritation.
Sodium lauryl sulphate(SLS)	May cause blindness and lead to cataracts. Eyes cannot heal properly. Retards the eye healing process.
Cetyl alcohol	Used as an opacifier, emollient, emulsifier, thickener, and carrying agent for other ingredients. Found in laxatives. May cause hives and contact dermatitis, skin disorders.
Cetalkonium chloride	Contact allergies, dry hair, ingestion can be fetal.
Cetearyl alcohol	May cause contact dermatitis and contact sensitisation in some people.
Cetearyl palmitate	May cause contact dermatitis.

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Herbal medicines:
Herbal medicines are now living in shelves in most health food stores. This is because as the population of the earth increases, so do the number of people who are experiencing illnesses. At the same time the current health care system is to overwhelm to give everyone access to the medical care that they may need. Therefore more and more people and turning to the ancient practice of using herbal medicines to self treat. Herbal medicines are widely manufactured and used are some doubts in terms of the safety and effectiveness of this type of medicines. Many people claim that herbal medicines are absolutely safe effective because they come from natural sources and therefore and labelled as “Herbal’’ or “natural”. ^{(8, 9)}

Examples of some commonly used herbal medicines:

• Echinacea extracts limit the length of colds in some clinical trials, although some studies have found it to have no effect.
• Garlic lowers total cholesterol level, mildly reduces BP, reduces platelet aggregation, and has antibacterial properties.
• Peppermint tea for problems with the digestive tract, including irritable bowel syndrome and nausea.

Dangers
A common misconception about herbalism and the use of natural products in general is that natural equal safe. However many plants have chemical defence mechanism against predators that can have adverse or lethal effects on humans. Examples are poison hemlock and nightshade, which can be deadly. Herbs can also have undesirable side effects just as pharmaceutical products can. These problems are exacerbated by lack of control over dosage and purity. Furthermore, if given in conjunction with drugs, there is danger of summation, where the herb and the drug have similar actions and add together to make an overdose. In animals, there are other dangers. There may be residues in food from farm animals (eg. eggs, milk, meat) or danger of doping in competition animals. The letter may also apply to human athletes. ^{(10, 11)}

STRUCTURE AND MECHANISM:
Structure and mechanism and molecules: A general overview
The surfactant molecules consist of polar and non polar segments. Dimension wise the non polar part is more dominant and polar groups generally constitute a smaller fraction of the total molecule. The polarity and non polarity is associated with definite radicals and groups and by linking these groups into molecules surfactant compounds can be generated at will. If this groups are linked together either directly or through ester, either and acid amide linkages surfactant molecules are produced. The behaviour of a given surfactant in a solution would largely be governed by the relative magnitude of the hydrophilic and hydrophobic groups constituting it. Surfactant molecules consist of a polar and non polar part and when they are place in two phases of differing polarities the non polar part gets oriented towards the phases of low polarity while the polar towards high polarity phases. ^{(12, 13)}

List of polar and non polar groups:

Name of polar groups	Name of non polar groups
Aldehyde Amino Carboxyl Ether Ketone Metallic salt sulfonates Nitro Phosphate Polyoxyethylene Sulphate esters	Alcohol Alkyl chains 8-18 carbon atoms Alkyl groups 3-8 carbon atoms Benzene nucleus Naphthalene nucleus Polyoxypropylene Rosin acids Terpenes Hydrocarbons 8-20 carbon Atoms and atoms

If the hydrophilic groups are stronger the compound will have a ready tendency to dissolve in water or other polar solvents since the polar groups will overcome the tendency of the non polar groups to resist dissolution. Similarly, if the hydrophobic groups be more powerful it will not allow the surfactant to dissolve in water but would tend to drag the molecule into non polar groups to resist dissolution.

Type of Enhancer	Name	Drug studied	Mechanism
Surfactant	Sod. Oleate	Taziphilline Atenolol Hydrocortisone Diltiazem Cerapamil	A. increase partitioning of drug in skin. b. decreases the trotuosity of the porous pathway in stratum corneum.
Surfactant	Polyoxy - Ethylene	Bovine serum albumin	Interact with stratum corneum to dispute the order of keratin filament within corneocytes.
Surfactant	Lauryl ether or brij 36T	Methyl nicotinate	Increase fluidity of stratum corneum, solubilise, and extract.
Surfactant	Alkyl methyl sulphoxide	Naproxen	Interact with stratum corneum to disrupt the order of keratin filament within corneocytes.
Surfactant	Sorbitan  trioleate polyoxy 8-stearate	Flufenamic acid	Disrupting the stratum corneum.

APPLICATION OF HERBAL SURFACTANT

1. Skin disinfectants, surgical hand preparations, Patient skin preparations and antimicrobial:
A hydroalcoholic lotion is disclosed which comprises (a) a lower alcohol and water in a weight ratio of about 35:65 to 100:0 and (b) between at least 0.5% and 0.8% by weigh thickener system comprised of at least one emulsifier present in at least 0.05% by weight wherein the composition in polymer free state has a viscosity of at least 4000 centipoise at 23 degrees (c) and wherein the emulsifier is comprised of at least one hydrophobic group and at least one hydrophilic group.^{(14, 15)}

2. Exogenous surfactant as a drug delivery agent:
Pulmonary surfactants is a complex mixture of lipids and several specific surfactants proteins, which together render it with unique spreading properties and a dynamic surface tension behaviour. These characteristics are heralded as ideal for a carrier of choice of instill therapeutic agents into the lung, because this combination enables high local therapeutic levels while minimising systemic side effects of the instilled agents. ^{(2, 16)}

3. Control of lung infection, allergy and inflammation:
Lung inflammation and infection is a growing problem, and the infections are routinely treated with antibiotics. The pharmaceutical industry is interested in the development of protein therapeutics, which can be used as alternatives to antibiotics. There is relatively fragile protective barrier, the alveolar lining layer, which controls the interaction between the atmosphere and the lung. The film, known as lung surfactant, plays two important roles, prevention of lung collapse during respiration and provision of a first line of defence against extremely varied range of particles, allergens and microbes that are present in the environment.^{(13, 16)} 

4. Targeted ultrasound drug delivery system:
Nanobubble surfactant based ultrasound contrast agent which is composed of a surfactant shell which has the capability of being modified to be loaded with bioactive compounds. It also has the capability of being modified on the surface with another bioactive moiety that would specifically target the agent to certain tissue types. This invention is capable of extravasations to specific tissue in areas such as a tumour and is capable of functioning as an ultrasound contrast agent.⁽¹⁷⁾

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5. As channelling agent to form sustain release medicine:
Polymers are frequently used in drug delivery system. By using polymer combinations, formulators may be able to develop sustained release drug dosage forms with better performance than is shown by the individual polymer components. Various polymer blends have been studied in order to achieve the desired release kinetics. The presence of more than one polymer in a formulation may result in special configuration, but it is also possible that a polymer additive may become part of the gel network.

6. In microemulsion electrokinetic chromatography:
Separation of small ions is also successful by using gel filtration columns and micellar solutions. In electrophoresis, especially capillary electrophoresis (CE), Micelles are used as pseudo-stationary phases in capillary zone electrophoresis (CZE). This mode is called micellar electrokinetic chromatography (MEKC). Most of the drug analysis can be performed by using the MEKC mode because of its wide applicability eg. Optimised separation of isoquinoline alkaloids in thalictrum herbal medicine.

7. Multivesicular emulsion drug delivery system:
A topical delivery composition which employs a multivesicular emulsion in combination with a pharmaceutically/pharmacologically active agent is disclosed. The multivesicular emulsion is formed from a quaternary amine salt emulsifier such as behentrimonium methosulfate. The emulsion is multi-lamellar which is a series of concentric spheres or vesiculars of oil and water phase that can be seen microscopically.^{(18, 19)}

8. As permeability enhancer in noninvasive route of drug delivery system:
The noninvasive route of delivery system has many advantages over the conventional delivery systems. Although its applications are limited by low skin permeability and physicochemical properties of drugs. The permeation of drugs through skin can be enhanced by various methods including physical method such as iontophoresis (applicable of low level electric current), phonophoresis (use of ultra sound energy), electroporation and by chemical penetration enhancers.
These are following necessities for penetration enhancement of drugs.
To improve the battery of less potent drugs with higher dose eg. Oxymorphane.
To increase the delivery of ionisable drugs at physiological pH eg. Timolol maleate.

9. In contraceptives for its spermicidal properties:
Structure:  Nonoxynol-9,   CH3 (CH2)_8-C₆H₅-(-0-CH2-CH2-)₉-OH
IUPAC name:    2-[2-[2-[2-[2-[2-[2-[2-[2-(4-nonylphenoxy)

Alternatives
Chemically speaking, there are two alternatives to nonoxynol-9-spermicide:
Octoxynol-9: In US, only octoxynol-9 is available. It is in cream or jelly only and is hard to find. Benzalkonium chloride: Benzalkonium chloride spermicide is only available in Canada and Europe. ^{(20, 21)}

10. Stool softer surfactants:
Laxatives:
Drug or other substance used to stimulate the action of the intestine in eliminating waste from the body. The term laxative usually refers to as mild acting substance; substances of increasingly drastic action are known as cathartics, purgatives, hydrogogues, and drastics, respectively.
Stool softeners/surfactants:These cause water and fats to penetrate the stool, making it easier to along. Many of these quickly produce a tolerance effect and so become ineffective with prolong use. They produce their action by acting on small intestine and the onset of action is around 12-72 hrs.

Docusate calcium/docusate sodium
Docusate a non-prescription laxative helps a patient avoid constipation by softening the stool. It works by increasing the penetration of fluids into the stool by emulsifying feces, water and fat. Docusate prevents constipation and softens bowel movement and fecal impaction. This laxative should relieve constipation within 1-3 days.

Precaution:
Docusate calcium/sodium should be avoided by patient with intestinal blockage, fecal impaction, or nausea and vomiting. Lactulose should be avoided by patients who have diabetes mellitus; eat a low galactose diet, or whose general health is poor.
Side effects include: Bitter taste in mouth, Irritated throat, Diarrhoea, Rash.

EVALUATIONS

1.By assisted pressurized hot water extraction for marker compounds In radix codonopsis pilosula using liquid chromatography:
· Liquid chromatography / Elecrospray ionisation mass spectrometry
In the above towards the elimination of organic solvents in the extraction process in botanicals, a new method combining surfactant and pressurized hot water extraction with an applied temperature below the boiling point and lower pressure from 10 to 20 bar was developed for the analysis of marker compound that are reasonably hydrophobic such as tetradeca-4E, 12E-diene-8, 10-diyne-1,6,7-triol and tetradeca-4E, 12E-diene-8, 10-diyne-1,6,7-triol-O-beta D glucose in Radix Codonopsis Pilosula (DangShen). Because reference substances for the proposed botanicals were not available, a method was developed to isolate the marker compound in Radix Codonopsis Pilosula.^{(4, 12)}

· Elect of two surfactants and mode of incorporation on the compaction characteristics of the hot water leaf extract of ficus sur:
The hot water leaf extract or ficus sur has been found to have antiulcer activity. Earlier formulation studies have investigated its tabletting properties. Surfactants are added to tablet formulations to increase the rate of drug release. This study was design to determine the effect of two different surfactants-sodium lauryl sulphate and tween 40 and their mode of incorporation on the compaction characteristics of the granule of hot water leaf extract.

2.      GPC analysis of a non-ionic surfactant mixture:
Generally, when analysing surfactants by gel permeation chromatography (GPC), the length of lipophilic group determines the separation. When surfactant mixtures are analysed by single-column GPC, the peaks often overlap, creating identification difficulties. This application Note describes the analysis of surfactants by combining two columns.^{(8, 22)}

3.      Evaluation of hydrophobic and hydrophilic parts:
Until the fifties of this century the selection of emulsifying agents for the preparation of emulsions was an arbitrary process based entirely on trial and error. At that time the number of available emulgents was limited and large number of new emulsifiers employed these days had not been evolved. As more and more surfactants began to grow out of the laboratories, the need for a rationale for their use in various formulations became imperative. Griffin devised a method as an answer to this need which was termed by him as the HLB system and was based on the balance between the hydrophilic and hydrophobic portion of the surfactant molecules. Each surfactant was assigned a number known as its HLB value which range from 1 to 40. Increase in the number of HLB value was indicative of simultaneous increase in the hydrophilic properties of the surfactant.

Groups number of some Hydrophilic and Lipophilic Groups

Groups	Group number
1.      Hydrophilic groups -COOH -COOK -COONa Ester (free) Ester (sorbitan ring) Hydroxyl (free) Hydroxyl (sorbitan ring) Ether Nitrogen (tertiary amine) SO4Na Hydrophobic groups -CH2-CH2-, CH3-, =CH- -(CH2-CH2-0) -(CH2-CH2-CH2-0)-	2.1 21.1 19.1 2.4 6.8 1.9 0.5 1.3 9.4 38.7   0.475 0.33 0.15

Utility of HLB Values
These values are certainly beneficial in selecting emulsifying agent for various lipophilic materials. As a help to a product development man, the broad ranges of HLB values, within which he could look for surfactants for use as wetting agents, solubilising agents etc. have also cited in the literature and are given below. If the HLB value of a surfactant is not known at least a range can estimated by stirring it in water and observing the resultant mixture. The following guidelines are available in the literature. (23)

Indication range of dispersion and respective HLB value

Indication range	HLB value
No dispersion Slight dispersion Milky dispersion on vigorous shaking Milky dispersion with upper end almost clear Clear dispersion Clear solution	1-4 3-6 6-8 8-10 10-13 More than 13

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H/L number:
H/L or hydrophile-lipophile number, first suggested by Moore and Bell, varies from 20-150. Compounds with strong lipophile tendency have a number of 20 while those with strong hydrophile groups a number of 150. A balanced surfactant would have H/L number in the region of 65. This method can be used for calculating the hydrophilic lipophilic balance of a series of non-ionic emulsifiers which are polyoxyethylene derivatives of higher alcohols or of fatty acids, phenols etc. The recommended formula for such calculation is:

H/L=      no.of ethylene oxide units
          ------------------------------
         no.of C-atoms in lipophilic portion

Water Number:
Water number is the number of mililiters of water required to pronounced turbidity when a dioxane benzene solution of a surfactant is titrated with water. The solvent mixture has a water number of 22.6. Water number can be related to HLB value in direct proportionally.

All these values and techniques give a sufficiently fair idea of the relative portions of polar and non polar groups in a given surfactant molecule. This information is essential in selecting surfactants for various formulations.⁽²⁴⁾

CONCLUSION

• A herbal surfactant is a natural Compound that can reduce the interfacial tension between two immiscible phases. Herbal surfactants are materials which have a tendency to preferentially get absorbed at the interface between two phases. Herbal surfactants are of three types hyper anionic, cationic, non-ionic.

• In addition to their used as emulsifies some non-ionic surfactant are used as solubility or wetting agents. Some macrogol ethers such as nonoxynol-9 are used as spermicides. Anionic surfactant are a group of surfactants which ionise in  aqueous media and whose surfactant activity related to anionic part those includes soaps, alkalimetal and ammonium soap, sulphated compounds sulphonated compounds. Cationic surfactants are mostly quaternary compounds some of them are however aminosalts, amino amides or immidazolines.

• Herbal surfactant molecule consist of a non polar and a polar part the non polar part gets oriented towards the phase of low polarity while the polar towards high polarity phase. The net result of their surface absorption is that tension between two phases is inevitably lowered and phases acquire greater tendency to intermix with each other. The surfactant molecules desend down into the bulk of the solution in the form of molecule aggregates or micelles of various shapes. The concentration of the surfactant at which it begins to form micelles is known as critical miceller concentration.

• Herbal surfactants have their use in skin disinfectants, surgical hand preparation, potent skin preparation and antimicrobial hand lotion.

• Exogenous surfactants are used as a drug delivery agents, like pulmonary surfactant which is a complex mixture of lipids and several specific surfactant proteins which together render it with unique spreading properties and dynamic surface tension behaviour surfactants are also used in the control of lung infection allergy and inflammation.

• Herbal surfactants are also useful in microemulsion electrokinetic chromatography. It is promising separation technique providing good selectivity and high efficiency sorbitan monooleate (tween 80). The biological surfactant cholic acid was introduced into the mobile phase in order to approach to the structure of natural membranes like erythrocyte and cytoplasmic membrane.

• The other application of herbal surfactant molecules are in multivascular emulsion drug delivery system like quaternary ammonium salt polysorabte 60 polysorabte 40 (tween 40) and as a permeability enhancer in non-invasive route of drug delivery system.

• Some Herbal surfactant like Nonoxynol-9 is used as a contraceptive for its spermicidal property. Herbal surfactant also has stool softener property it acts an small and large intestine and its duration of action is 12-72 hours Docusate calcium and Docusate sodium are used as stool softener surfactant are also used in cutaneous cleanser in liquid facial cleansers.

• Herbal surfactant can be evaluated by assisted pressurized hot water extraction for marker compounds in Radix codonopsis pilosula using liquid chromatography and elecrospray ionization mass spectrometry.

• Gel permeation chromatography is also used for the evaluation of non ionic surfactant mixture the length of the lipophilic group determines the separation.

• Evaluation of hydrophilic and lipophilic part is given by a system called HLB system that is based on the balance between hydrophilic and lipophilic portion of the surfactant. This value id certainly beneficial in selecting emulsifying agents for various lipophilic materials. Other parameters for evaluation of hydrophilic lipophilic part are H/L number and water number.

• Many Herbal surfactants are either derived completely form petroleum based raw materials or from a mixture of petroleum and vegetable oil-based material currently highly purified glucose and sucrose based surfactants are produced in house. These find application in specialized area such as biomedical research, pharmaceutical formulations capsule coating and as therapeutic agents. Individual herbs or mixtures of herbs that are used for therapeutic value are called herbal medicine use of natural plant substances to treat and prevent illness.

• Herbalism or Phytotherapy is folk and traditional medicinal practise based on the use of plant and plant extract.

• Some commonly used herbal medicines are Echinacea extracts, Garlic to lower total cholesterol levels, peppermint tea for problem with digestion tract, Nigella sativa for diverse hypertension and stomach ache, grape fruit seed extract for very effective antibacterial, anti parasitic, rauwolfia serpentina used for sleepnessness.^{(4, 17, 23)}

REFERENCES:
1.Gennaro, A.R, Remington: The Science and practice of Pharmacy, 21st edition, 2005, Lipincott William and Wilkins, Vol.I, 290.
2.Martin, A., Bustaminite, P and chun, A.H.C., Physical Pharmacy, 4th edition, 1996, Lippincott Williams and Wilkins, Baltimore, 370-392.
3.Lachman, L., Lieberman, H.A., and kanig, J.L., The Theory and practice of Industrial Pharmacy, 3rd edition, 1991, Varghese Publishing House, Bombay, 100-106.
4.Ansel, H.C., Introduction to Pharmaceutical Dosage Forms, 4th edition, 1985, K.M.Varghese Company, Bombay, 86,223,337.
5.Gutzschebauch, C., Vantoof, G., King, H, Kluppel, H.J., Saouter, G., and Taylor, T., 2001 Europan climate change programe (ECCP).
6.Vandeplassche, E.J., DeBujn, J.H.M., Stephenson R.R., Marshall, S.J., Feijtel, J.C.J. and Belanger, S.E., 1999, Environ Toxical Chem 18, 2563-2663.
7.Carter, S.J., Cooper and Gunn’s, Tutorial Pharmacy, 6th edition, 1991,CBS Publisher and Distributors, New Delhi, 40-41,66-68.
8.Subrahmanyam, C.V.S., Textbook of Physical Pharmaceutical, 2nd edition, 2005, Vallabh Prakashan, Delhi, 148-149.
9.Tripathi, K.D., Essential of Medical Pharmacology, 5th edition, 2003, Jaypee Brother Medical Publishers (P) Lit, New Delhi, 611-612.
10.Mithal, B.M., A Text Book of Pharmaceutical Formulation, 4th edition, 1996, Vallabh Prakashan, Delhi, 77-84,86-91.
11.Abdul, A.S., T.L. Gibson, C.C. Ang, J.C. Smith, and R.E. Sobczynski. 1992. Ground Water 30:219–231.
12.Adamson, A.W. 1990. Physical chemistry of surfaces. 5th ed. John Wiley, New York.
13.Brown, C. L., Pope, G. A., Abriola, L. M., Sepehrnoori, K., Simulation of surfactant-enhanced aquifer remediation, Water Resources Research, vol. 30 no. 11 pages 2959-2977
14.EPA1, Remediation Technologies Screening Matrix, Prepared by the DOD Environmental Transfer Committee, in press 1994
15. frtr.gov, (online version of Remediation Technologies Screening Matrix, Prepared by the DOD Environmental Transfer Committee, in press 1994) last accessed April 1, 1999
16.Ahel M, McEvoy J, Gieger W (1993) Bioaccumulation of the lipophilic metabolites of nonionic surfactants in freshwater organisms. Environmental pollution 79:243-248
17.Scott HW, Patoczka JB, Mirenda RJ, Porter BA, Miller E (1989) Acute toxicity of industrial surfactants to Mysidopsis bahia. Arch Environ Contam Toxicol 18:765-772
18.Smith JT, Vinjamoori DV (1995) Rapid determination of logarithmic partition coefficients between n-octanol and water using micellar electrokinetic capillary chromatography. J.Chromatogr B 669:59-66
19.Rankin JC, Stagg RM, Bolis L (1982) Effects of pollutants on fish gills. In: Houlihan DF, Rankin JC, Shuttleworth TJ (eds) Gills. Society for Experimental Biology Seminar Series 16. Cambridge University Press, Cambridge, pp 207-219
20.Tolls J, Sijm DTHM (1999) Bioconcentration and biotransformation of the non-ionic surfactant octaethylene glycol monotridecyl ether 14C-C13EO8. Environ Toxicol Chem 18:2689-269
21.Tolls J, Sijm DTHM, Kloepper-Sams P (1994) Surfactant bioconcentration - a critical review. Chemosphere 29:693-717
22. Tolls J, Haller M, De Graaf I, Thijssen MATC, Sijm DTHM (1997) Bioconcentration of LAS: experimental determination and extrapolation to environmental mixtures. Environ Sci Technol 31:3426-3431
23. Tolls J, Haller M, Labee E, Verweij M, Sijm DTHM (2000) Experimental determination of bioconcentration of the nonionic surfactant alcohol ethoxylate. Environ Toxicol Chem 19:646-653
24. Ukeles R (1965) Inhibition of unicellular algae by synthetic surface active agents. J Phycol 1:102-110

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