Hydrophile-Lipophile Balance HLB

In most cases, these active defoaming components are insoluble in the defoamer formulation as weU as in the foaming media, but there are cases which function by the inverted cloud-point mechanism (3). These products are soluble at low temperature and precipitate when the temperature is raised. When precipitated, these defoamer—surfactants function as defoamers when dissolved, they may act as foam stabilizers. Examples of this type are the block polymers of poly(ethylene oxide) and poly(propylene oxide) and other low HLB (hydrophilic—lipophilic balance) nonionic surfactants. 

Ethoxylated fatty alcohols and alkylphenols were used. The products available on the market make up homologous series containing an average of between 3 and 100 ethylene-oxide groups. They thus have a wide HLB (hydrophilic/lipophilic balance) range. Besides, they are among the least expensive surfactants on the market. 

HLB (hydrophile-lipophile balance) system, 70 126 HLB value, 72 54, 55 HMG-CoA, role in cholesterol synthesis, 5 142... 

The temperature (or salinity) at which optimal temperature (or optimal salinity), because at that temperature (or salinity) the oil—water interfacial tension is a minimum, which is optimum for oil recovery. For historical reasons, the optimal temperature is also known as the HLB (hydrophilic—lipophilic balance) temperature (42,43) or phase inversion temperature (PIT) (44). For most systems, all three tensions are very low for Tlc < T < Tuc, and the tensions of the middle-phase microemulsion with the other two phases can be in the range 10 5—10 7 N/m. These values are about three orders of magnitude smaller than the interfacial tensions produced by nonmicroemulsion surfactant solutions near the critical micelle concentration. Indeed, it is this huge reduction of interfacial tension which makes micellar-polymer EOR and its SEAR counterpart physically possible. 

Microemulsions are transparent or translucent, thermodynamically stable emulsion systems (Griffin 1949). Forming a middle phase microemulsion (MPM) requires matching the surfactant system s hydrophobicity with that of the oil. The HLB (hydrophilic-lipophilic balance) number reflects the surfactant s partitioning between water and oil phases higher HLB values indicate water soluble surfactants while lower values indicate oil soluble surfactants (Kunieda et. al. 1980, Abe et. al. 1986). While a balanced surfactant system produces middle phase microemulsions, an underoptimum surfactant system is too water soluble (high HLB) while an over-optimunTSystem is too oil soluble (low HLB). 

The amphiphilic nature of many emulsifying agents (particularly non-ionic surfactants) can be expressed in terms of an empirical scale of so-called HLB (hydrophile-lipophile balance) numbers222 (see Table 10.1). The least hydrophilic surfactants are assigned the lowest HLB values. Several formulae have been established for calculating HLB numbers from composition data and they can also be determined experimentally - e.g. from cloud-point measurements123,125. For mixed emulsifiers, approximate algebraic additivity holds. 

Anthocyanins are generally more stable at an acidic pH. Therefore, anthocyanins are commonly extracted under cold conditions using either acidic methanol or ethanol to avoid degradation1 5169 (Table 3.4). In comparison, acetone allows more reproducible extraction and avoids problems with pectins. However, it is limited by the coextraction of proanthocyanins.39 In general, ethanol is preferable as an extraction solvent, although it can require an additional step for the removal of lipid-soluble substances. SPE using Ci8, polyamide, HLB (hydrophilic lipophilic balanced stationary phases), or Amberlite has been employed for the purification of anthocyanidins prior to HPLC analysis.39-51 66 69... 

Notes LOD, limit of detection MeOH, methanol EtOH, ethanol ACN, acetonitrile EtAC, ethyl acetate SPE, solid phase extraction HLB (hydrophilic lipophilic balanced) TFA, trifluoroacetic acid GC, gas chromatography TMS, trimethylsilyl MS, mass spectrometry HPLC, high-performance liquid chromatography DAD, diode array detector NMR, nuclear magnetic resonance ESI, electrospray ionization APCI, atmospheric pressure chemical ionization CE, capillary electrophoresis ECD, electrochemical detector CD, conductivity detector TLC, thin layer chromatography PDA, photodiode array detector. 

For abbreviation of analyte names see Sect. Abbreviations . ACN acetonitrile, CBA carboxylic acid, FA formic acid, HLB hydrophilic-lipophilic balance, hum human, IS internal standard, LRC large reservoir capacity, MCX mixed-mode cation exchange, metab. metabolites (biotransformation products produced in vivo), MeOH methanol, n.s. not specified, OAc acetate, PB phosphate buffer, PBS phosphate-buffered saline, SCX strong cation exchange Ratio given as v/v... 

The solubility of the surfactant of polyethyleneglycol type in different phases can be described by the HLB (hydrophilic-lipophilic-balance) concept [ 27]. This concept attributes to the molecule a HLB number that represents the geometric ratios of the hydrophilic and the hydrophobic moieties. It should, however, be emphasized that the HLB does not represent a fundamental property of the system but is based on experience. For fatty alcohol ethoxylates... 

In inverse polymerization, water-soluble monomers are emulsified with low HLB (hydrophilic-lipophilic balance) surfactants in an organic medium and the reaction is initiated with water-soluble or oil-soluble initiators. A review of the subject can be found in a recent publication of Greenshields [46]. 

HLB = hydrophilic-lipophilic balance. a Grinsted Products A/S, Brabrand, data sheets. 

The Span 80 with an HLB (hydrophilic-lipophilic balance number) of 4,3, which is an oil soluble liquid, was used as surfactant. The effect of the continuous medium was investigated by employing 1,1,2,2-tetrachloroethane, toluene, or decane, which have various degrees of hydrophobicity. The amounts of the components used are listed in Table 3. At room temperature (20 °C), concen-... 

Tween 80 (also known as At-Plus 109 and Polysorbate 80) is a polyoxyethylene sorbitan monooleate and was obtained from Atlas Chemical Industries, Inc. This nonionic surfactant has an HLB (hydrophile-lipophile balance) of 15.0 and is used as an emulsifier, solubilizer, and dispersant. It was used without further purification at the 0.1% (w/v) level in partitioning and greenhouse herbicidal evaluations as described below. 

Becher and Becher (2) measured the spreading pressure, tt, of a series of surfactants on plant and synthetic surfaces. The surfactants were characterized by HLB (hydrophile-lipophile balance) values (3) similar to those of Jansen s adjuvants. The relationship between the spreading pressure and the contact angle can be expressed as tt = yL cos 0, where yL is the surface tension of the liquid and 6 is the contact angle between the liquid and a solid surface. Becher and Becher demonstrated that surfactants in their series which exhibited maximum spreading pres-... 

One of the difficulties is that there is no convenient theory for selecting the appropriate surfactants a priori. The simplest procedure is to try to match the HLB (hydrophile-lipophile balance) character of the surfactants to the polarity of the particular polymers. Tabulated HLB values are available [23, 24] (the higher the HLB number the more hydrophilic is the soap), but the rating is essentially empirical and effective use requires some experience and intuition. 

The manner in which lecithin is modified to achieve increased hydrophilicity will greatly affect its emulsification properties. Different modifications will create lecithin products with different apparent HLB (hydrophile-lipophile balance) values, a term used to convey the approximate degree of water dispersibility (hydrophilicity) of lecithin products (31). The higher its HLB value, the more water dispersible the lecithin product. In o/w emulsions, the type of fat to be emulsified may require a specific type of hydrophilic lecithin for optimum emulsion stability. Dashiell (31) provides a short listing of fat types, and the corresponding class of lecithin found to give the most stable emulsion in model systems of water/fat/ emulsifier. 

CMC Critical micellization concentration DP Degree of polymerization HLB Hydrophilic-lipophilic balance MSA Methanesulfonic acid... 

A frequently used method is known as the HLB (hydrophile-lipophile balance) method. In this method (Griffin, 1949), a number (0-40) indicative of emulsification behavior and related to the balance between the hydrophilic and lipophilic (hydrophobic) portions of the molecule has been assigned to many commercial emulsifying agents. (In some cases, the HLB number is calculated from the structure of the molecule in other cases, it is based on experimental emulsification... 

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