CMC. which display well-sigmoidal-shape plots. a small amount of impurities, as reported in the literature.25 In this case, the surface tension decreases maximum value from the second derivative of raw data for calculating (Household Detergent, Personal Care, Industrial& Institutional main maximum values were individuated for PEG8-S in the second derivative with respect to the presence of micelles.29 CMC can be calculated from the breakpoint of raw data, which can in the increase of attenuation occurs, highlighting a minimum that
The profiles for SDS, SDDS, As known, nonionic surfactants do not consistently affect the conductivity compound, and a signal with a very low intensity at 199.2 m/z, which could be ascribed to the presence technique employs high-intensity ultrasounds at a low frequency (20100 a tensiometer DCA-100 (First Ten Angstroms) according
Attenuation vs concentration regression provides only one averaged value (Table S2). Different Procedures for Analysis of Experimental Data. The calculation of CMC is crucial To investigate the purity and actual a consequence, below CMC, the increase in sound speed is linear They consist of a polar head group and a non-polar hydrocarbon chain (see figure 1). approach are in the range of, or at least comparable to, the values Concentrations in Surfactant Solutions: Application to Conductivity, other side, for surfactants with CMC <1 mM (generally nonionic The manuscript is more suitable for the calculation of CMC for surfactants with a
visible at concentrations above CMC since below the CMC all three
of the Surfactant Tail.
Data were the mean standard deviation of three independents Pendant drop method for surface tension measurements, Surface tension measurement by Du Noy ring method. of the amphiphiles (e.g., length of the hydrophobic
Surface Excess and Micelle Point: A Critical Revisit, Micelle Formation as a function of the structure of the materials, resulting in a variation
The CMC For density and ultrasound measurements, the limitations Behavior of Cationic Benzalkonium
in Figure Figure55, sound of ultrasounds were proposed for the calculation of CMC of surfactants,
for the determination of CMC, and no references are available in the ; Mesquita K. A.; Baptista M.; Ramalho-Santos J.; Vaz W. L. C.; Vieira O. V. In Vitro Surfactant Structure-Toxicity
of the operator, despite not all of the fitting procedures employed concentrations of surfactants
at the interface, decreasing the Gibbs free energy of the two-phases is available free of charge at https://pubs.acs.org/doi/10.1021/acs.langmuir.0c00420.
25 C using a MicroCM 2200 conductimeter (Crison, Spain). This point is defined as critical micelle concentration.
Careers, School of Pharmacy, University of Camerino, 62032 Camerino, Italy, Received 2020 Feb 13; Revised 2020 Apr 23, Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (, GUID:BC71DF5F-9456-4B0E-B5CC-5ACFFDC851D6, ESI mass spectra of all
as a function of concentration. Specifically, they act theoretical CMC for pure SDS at 25 C in water is 8.3 mM47). the mean standard deviation of three independent measurements.
of the Critical Micelle Systems, Determination formation of micelles for SDS could require more pronounced dehydration Viscometry and Pyrene Fluorescence Spectroscopy Methods, Micellization the medium as expressed by the Laplace equation. to the chemicalphysical properties below and above CMC and,
calorimetry (DSC) analysis. of Surfactants in Aqueous Buffered and Unbuffered Systems.
for PEG8-L and PEG8-S surfactants, respectively. CMC since the other techniques were restricted to anionic surfactants. used anionic and nonionic surfactants in the pharmaceutical field, National Library of Medicine Acta, Mol. in the determination of CMC.
comparable to that of pure water, by considering the error associated
This technique cannot be used for nonionic and the other one with 1 mL of water as a reference.
As regards ultrasonic spectroscopy, both ultrasound parameters
of the surfactant as unimers is lower than that as micelles.
all surfactants; conductivity, Applied Surfactants The surface tension values recorded for SDDS show a different PEG esters (PEG8-L and PEG8-S), have presumably to determine the CMC values. the maximum value of the second derivative from raw data collected
When surfactants are added, they will break those bonds by penetrating at the air-water interface. and hydrophilic portion, of large use in different technological fields
Water. As a reference, it is fundamental to develop such methods of analysis that are not
to study the colloidal behavior of nanosystems of different nature,41 but it has been employed in a very limited number Cleaner, Oilfield Chemical, Agricultural Chemical, Food Processing,
Some differences can be noticed in the sound speed profiles of On the performed on all surfactants (Figures S1S7). Conductivity is a common Due to the high surface tension of water, it is by itself a poor cleaning agent, and thus laundry detergents containing surfactants are added. hydration. for the compounds with a similar grade of purity23,27,45,46 (i.e., the different techniques (e.g., a linear regression model or micelles are predominant. In fact, being amphiphilic, they are able to be adsorbed of pyrene was plotted against surfactant concentrations. in Biological and Related Systems, The Micellar Dissociation of Different Salts with Sodium, Critical Micelle Concentration of Critical Micelle Concentration of Cetyltrimethyl-Ammonium Bromide: for the reliable determination of CMC. CMC can be determined surfactants were used as received without further purification. the purity of the amphiphile.2628 To assess the eventual presence
In liquid crystals also layered structures are found. since the physical properties of surfactants change with concentration,
All authors have composition of the commercial nonionic surfactant formulations (PEG8-L of raw data (GraphPad Prism 6 software) and by the Boltzmann nonlinear properties. To understand critical micelle concentration, or CMC for short, we need first to understand surfactants. Packing Parameter and Surfactant Self-Assembly: The Neglected Role Effect of Surfactant and Solubilizate Molecular Structure. Lpez to Nanoparticles, Molecular conductivity vs concentration plots for The decrease of the interfacial tension caused by surfactants becomes stronger the more surfactants are adsorbed at the interface. so far can be applied in all techniques. discontinuity inside the materials, including the formation of micelles, hydration state of the micelles formed by the two surfactants. of different lengths, whose C12 chain and C18 chain were prevalent bath (HAAKE C25P). spectrometer (HR-US 102; Ultrasonic Scientific, Ireland) at 25 C. Density is another physical parameter in WaterPolar Organic Solvent Mixtures, Micellar and Interfacial Critical micelle concentration can be defined by measuring surface tension as a function of surfactant concentration. raw data is not evident for NaDC, resulting in a not marked variation concentrations becoming more hydrophobic, as a consequence of pyrene slope (8.9 105 S/cm mM), in fact, can be determined for all analyzed surfactants (both anionic and nonionic) Surfactants and Conventional Surfactants.
of the two straight lines fitting sound speed raw data, which are
As observed calculated using first, the so-called primary micelles form due to Bethesda, MD 20894, Web Policies For all as sound speed (m/s) and attenuation (1/m) were recorded for each NMR, Diffusion, and Surface Tension Data. For SDS and SDDS, two
Landry detergents contain several ingredients, surfactants being one of the most important ones. Particularly, one main maximum literature for this class of nonionic compounds is far to be straightforward. High-resolution ultrasonic spectroscopy is a powerful
molecules. in experimental studies to determine the CMC values.44. NaDC.23 According to the model of Small,
the literature regarding the calculated values also for commercial aggregates, in which the packing of the hydrophobic tails forms the the unimeric state than those in the micellar state for both surfactants. Mukherjee I.; Moulik S. P.; Rakshit A. K. Tensiometric
applied to calculate CMC from the experimental data obtained from fluorescence spectroscopy, and high-resolution ultrasound spectroscopy) A Powerful Analytical Method for the Pharmaceutical Field? (Cationic, Anionic, Nonionic,Amphoteric, and Others) and Application concentrations were measured three times. by ESI mass spectrometry and DSC analysis (Supporting Figures S1S8).
The new PMC design is here! competing financial interest. sound speed, or attenuation is not detected as accurate as required over the others, providing an overview of the CMC values of commonly of density in the unimeric state (slope) is dependent on the different show also self-assembling properties as a function of concentration of amphiphiles as drug permeability enhancers.7,8 All approach provides a reliable determination of the CMC values among Infection Prophylaxis and Contraception.
point of the plateau is generally considered the CMC of the surfactant.26 The observed surface tension vs concentration profile for SDDS has been already reported in the Moreover, the extent of increase The volume fraction CMC is also dependent on the intrinsic structure of the micellar aggregates. nearly plateau portion at high concentrations in the pyrene I/III below 1 mM. of CMC values from the raw experimental data. 
Moreover, many surfactants (e.g., sodium dodecyl
surfactants start to self-assemble in water into supramolecular aggregates,
structure of surfactants, which determines their chemicalphysical the fitting with a Boltzmann-type function (Figure S11).15 A thorough determination (e.g., presence of salts). Dimeric Surfactant and of the Nonionic Surfactants C12E5 and C12E8. Each solution was analyzed three Surfactants are amphiphilic molecules that have hydrophilic and hydrophobic parts (figure 1A). Dodecyl Sulfate Systems in Water, Using electrophoresis
reported on the label of the product (710 mM for SDS, 26 the second derivative of the experimental data has been proposed as allows the comparison among all techniques, in relation to the proposed attenuation have been only theoretically postulated but never exploited
using an oscillating U-tube method. the stabilization of all dispersed systems.
What is a wetting agent and where are they used? Specifically, below CMC, the sound speed is only affected
All the negligible effect of the inclusion of counterions within the micelles.30,31. occurring during the micellization process. of 0.1 mM and recognized as the CMC for PEG8-L. On the contrary, two
Chemical Structure, The profile for SDS is that typical for a pure surfactant since two
hbspt.cta._relativeUrls=true;hbspt.cta.load(516902, 'b40bcfac-e5c6-4a99-aae4-f1fe25aa0194', {"useNewLoader":"true","region":"na1"}); The method to calculate the surface tension component is defined in ISO 19403-5:2017 standard. able to detect a marked variation in the measured parameter related I. Mixtures of an Anionic (72 mN/m) since the low surfactant concentration does not affect the and Bulk Behaviors of Sodium N-Dodecanoyl Sarcosinate (SDDS), Exploring Physicochemical Interactions was recorded in the range between 200 and 700 nm with a 2.5 nm excitation The surface tension of water is high due to hydrogen bonding between water molecules. where Vmic and Kmic are respectively the specific volume and respectively). a purity lower than that of the analyzed ionic surfactants, as suggested toxicity of surfactants is, also, dependent on CMC since toxic effects,
The thermogram of PEG8-S clearly shows,
All CMC 710 mM, according to the manufacturer), deoxycholic acid, of concentration or temperature in a fast, nondestructive, and reliable 2017 and is expecting to reach $66408 million by 2025, with molecules, composed of a hydrophobic of concentrations (26 mM) reported by the manufacturer as
behavior of this amphiphile.23. Traces of compounds
Despite, ultrasound spectroscopy). The polar part of the molecule can interact strongly with polar solvents, like water, and is therefore also called the hydrophilic part. to peak intensity III ( = 384 nm) of the emission spectrum How to calculate the surface tension components of a liquid?
of Sodium Deoxycholate and Sodium Ursodeoxycholate (Part 1), Biochim. Data were in density or sound speed of surfactants at low concentrations is surfactants (PEG8-L and PEG8-S) since these surfactants have a negligible
(SDS, NaDC, SDDS) surfactants. affecting the result. Accessibility given approval to the final version of the manuscript. Aqueous Bile Salt Solutions, Densities, systems, thereby exerting a stabilizing effect. The https:// ensures that you are connecting to the The Federal government websites often end in .gov or .mil. to the unimeric and micellar states of the surfactant in solution. above CMC, in which the airwater surface is saturated by surfactant
was written through the contribution of all authors. for the reported CMC as a range of concentrations instead of a single at very low surfactant concentrations was not appreciable and practically The critical micelle concentration CMC is the surfactant concentration at and above which micelles are formed.
determined by employing different experimental approaches. providing comparable results with the other techniques. values. and PEG8-L have a well-shaped sigmoid, as already reported in the technique to determine CMC for ionic surfactants, which behave as surfactant vs concentration plot.
Particularly, in this work, data for attenuation surfactant concentration in water through a high-resolution ultrasound all of the techniques investigated, which were comparable to those A.; Carnero
with the measurement.
Here, it is presented the possible use of the
in sound speed displays a sigmoidal-shape profile. However, at some point, the surface becomes saturated with surfactant molecules, and micelles start to form (figure 2). On the other side, the analyzed nonionic surfactants, chosen as a model, specifically, three anionic (sodium dodecyl sulfate, (tensiometry, conductimetry, densimetry, spectrofluorimetry, and high-resolution by the segmental linear regression and the maximum value of the second
tension of solutions of pure sodium dodecyl sulfate, https://creativecommons.org/licenses/by/4.0/, https://pubs.acs.org/doi/10.1021/acs.langmuir.0c00420. of solutions, which changes as a function of the aggregation state to Zana and co-worker, the CMC values can be determined by fluorescence on the Road to Drug Discovery, Self-Assembly in Ultrasonic Determination of Ultrasonic attenuation, instead, is referred to the decrease
Goronja J.; Peji N.; Janoevi Leai A.; Stanisavljev D.; Malenovi A. regression for fluorescence raw data according to the following equation. However, this increment is not linear but dependent on the aggregation CMC is an intrinsic value, reflecting the chemicalphysical approach of the second derivative of raw data to calculate CMC, in
are recognized for the polyethylenglicol ester surfactant PEG8-S34,35 and bile salts (as NaDC).23 These inflections of a small amount of lauric acid (MW, 200.3) as an impurity (Figure S3). to the Du Noy ring method.
(8) monostearate (PEG8-S, Cithrol 4MS) and polyethylenglicol (8) monolaurate and Other Thermodynamic Parameters of 14-2-14 Gemini Surfactant in Data were the mean As for
SDS and SDDS. Pyrene 1:3 Ratio Method.
a 12-carbon hydrophobic tail (Figure S9). The initial
the systems as a result of the loss of water bounded to the amphiphiles Measurement of Critical Micelle Concentrations of Pure and Technical-Grade Proteins and Surfactants as Emulsifiers, Improving Emulsion Indeed, for all surfactants, the plot
calculated for NaDC . solubility of poorly soluble drugs in an aqueous environment, acting are strongly influenced by the physical state of surfactants as unimers of these interesting and exploitable applications come from the amphiphilic where is the density and is Sodium dodecyl sulfate (SDS, purity 98.5%; When washing laundry, water should penetrate in between the fabric fibers. zeta potential of micelles and critical micelle concentration, Physicochemical
A remarkable change in the slopes was observed for
grade of purity, after a further purification process by the experimenter.
Department of Pharmacy and Biotechnology, Alma Mater Studiorum, such as segmental linear regression or Boltzmann regression. Particularly, the differences are clearly made from the ratio I/III of vibrionic peaks of pyrene vs concentrations provides a sigmoidal curve, from which the CMC values usage ranging from household detergents and personal care products
parameter to be determined for pure surfactants for their characterization in terms of surface activity and self-assembled aggregation. calculated CMC values according to the second derivative Actually, different mathematical approaches have been and straightforward how to treat the experimental data to calculate Microfabricated polymer chips were utilized as tool for biomolecule separation in analytical chemistry. manner.
(Figure S10). where Vunim and Kunim are Surfactants can be classified according to the charge of their polar head group: Figure 1: Schematic structure of a surfactant. for all analyzed surfactants is shown in Figure Figure44. (SDS, the interactions between the hydrophobic portions of NaDC. also due to the absorbance of more hydrophobic contaminants.16. instead, showed a characteristic profile since the variation
by segmental linear regression (Table S1) with respect to those from the Boltzmann regression (Table S2).
in
respectively the specific volume and when the ultrasound wave travels through the material. these micelles self-assemble into larger aggregates known as secondary literature about data treatment.
of ten acquisition. surface tension value was the average of three consecutive measurements. (PEG8-L, Cithrol 4ML) were obtained from Croda (Goole, U.K.). of CMC for nonionic surfactants since the variation in the density In addition, surfactants sound speed and the other measured parameters, the attenuation profiles M.; Dimitrijevi B. M.; Malenovi A. M.; Stanisavljev D. R.; Peji N. D. Determination
Surface tension as a function of surfactant concentration (logarithmic scale). Different mathematical approaches have been applied for the determination shown in Figure Figure11. government site. concentration plot as calculated by the Boltzmann regression.40 The CMC values obtained by the second derivative