Separation of aliphatic and

Analytical Properties Separation of compounds containing the NH4+ group, such as amino acids and peptides the coated silica also behaves as a reverse phase for the separation of aliphatic and aromatic acids high selectivity for glycine and tyrosine oligomers Reference 59... 

Fig. 3-101. Separation of aliphatic and aromatic polyphos-phonic acids. — Separator column IonPac AS7 eluent 0.04 mol/L HN03 detection and injection volume see Fig. 3-97 solute concentrations 100 ppm each of 1, 5, 8, 9, and 6.

Examples of EKC methodologies for aromatic amines in water - are compiled in Table 31.4. Figure 31.4 illustrates the electromigration separation of aliphatic and aromatic amines. 

M. Pawlowska, J. Zukowski and D.W. Armstrong, Sensitive Enantiomeric Separation of Aliphatic and Aromatic Amines Using Aromatic Anhydrides as Non-chiral Derivatizing Agents, J. Chromatogr. A, 666(1994)485. 

Micropacked columns are available with most of the bonded-phase packings used in HPLC. Porous and non-porous silica particles are optionally functionalized with covalently ound silanes or other strongly adsorbed materials. ALkyl-bonded silicas produce separations, generally based on solute volatility, but with the potential for selectivity differences based on interaction with silanol groups. Underivatized silica is popular for petroleum separations of aliphatic and aromatic hydrocarbons. Silver-ion-containing silica columns are selective for olefin separations. Huoroalkyl-bonded... 

Figure 6.62 Separation of aliphatic and aromatic carboxylic acids on OmniPac-PAXlOO with a NaOH concentration gradient. Column dimensions 250 mm x2 mm i.d. eluent NaOH/MeOH (95 5 v/v) gradient linear, 40-280 mmol/L in 15 min flow rate 0.25 ml/...

Skelly, N.E. Separation of aliphatic and aromatic acids, aromatic sulfonates, quaternary ammonium compounds, and chelating agents on a reversed-phase column without ion pairing, J.Chromatogr.ScL, 2003, 41, 22-25. [nonoxynol-9 citric add benzenesulfonic acid phthsilic acid hydrobromic acid nitrUotriacetic acid oxalic acid nitric acid hydriodic acid glycolic acid formic add nitrous add cyanuric acid lactic acid acetic acid NTA benzalkonium EDTA]... 

For the separation of aliphatic and aromatic acids, especially from substances of nonionic character, paper electrophoresis can be applied successfully. With a potential drop of lOV/cm and with 2n ammonia or 1 N acetic acid as a buffer, the separation can be carried out in 2 hr. Mono-, di-, and polysulfonated derivatives are also separated, but not isomeric sulfonic acids. Detection is carried out as in paper chromatography. 

Separation of Aromatic and Aliphatic Hydrocarbons. Aromatics extraction for aromatics production, treatment of jet fuel kerosene, and enrichment of gasoline fractions is one of the most important appHcations of solvent extraction. The various commercial processes are summarized in Table 4. 

Taft began the LFER attack on steric effects as part of his separation of electronic and steric effects in aliphatic compounds, which is discussed in Section 7.3. For our present purposes we abstract from that treatment the portion relevant to aromatic substrates. Hammett p values for alkaline ester hydrolysis are in the range +2.2 to +2.8, whereas for acid ester hydrolysis p is close to zero (see Table 7-2). Taft, therefore, concluded that electronic effects of substituents are much greater in the alkaline than in the acid series and. in fact, that they are negligible in the acid series. This left the steric effect alone controlling relative reactivity in the acid series. A steric substituent constant was defined [by analogy with the definition of cr in Eq. (7-22)] by Eq. (7-43), where k is the rate constant for acid-catalyzed hydrolysis of an orr/to-substituted benzoate ester and k is the corresponding rate constant for the on/to-methyl ester note that CH3, not H, is the reference substituent. ... 

Naphthalenedisulfonate-acetonitrile as the only mobile phase with a silica column coated with a crosslinked aminofluorocarbon polymer has proven to be an effective combination for the separation of aliphatic anionic surfactants. Indirect conductivity and photometric detection modes are used to monitor these analytes. The retention of these surfactants is found to depend on both the ionic strength and the organic solvent content of the mobile phase. The mechanism of retention is considered to be a combination of both reverse phase and ion exchange processes. Selective separation of both alkanesulfonates and... 

In contrast to traditional methods for total petroleum hydrocarbons that report a single concentration number for complex mixtures, the fractionation methods report separate concentrations for discrete aliphatic and aromatic fractions. The petroleum fraction methods available are GC-based and are thus sensitive to a broad range of hydrocarbons. Identification and quantification of aliphatic and aromatic fractions allows one to identify petroleum products and evaluate the extent of product weathering. These fraction data also can be used in risk assessment. 

One particular method is designed to characterize Ce to C28+ petroleum hydrocarbons in soil as a series of aliphatic and aromatic carbon range fractions. The extraction methodology differs from other petroleum hydrocarbon methods because it uses n-pentane, not methylene chloride, as the extraction solvent. If methylene chloride is used as the extraction solvent, aliphatic and aromatic compounds cannot be separated. 

Few analytical methods are available for the determination of total petroleum hydrocarbons in biological samples, but analytical methods for several important hydrocarbon components of total petroleum hydrocarbons may be modified. Most involve solvent extraction and saponification of lipids, followed by separation into aliphatic and aromatic fractions on adsorption columns. Hydrocarbon groups or target compounds are determined by gas chromatography-flame ionization or... 

Many contributions regarding silica monolithic columns were published by the group of Tanaka [93,189,196]. In their early work, they reported on the successful separation of alkyl benzenes, which are representative for the separation of many low-molecular-weight compounds, containing aromatic groups. Tanaka et al. also combined a conventional column in the first dimension with a silica rod column for the fractionation of aliphatic and aromatic hydrocarbons [197]. The successful separation of the 16 EPA priority pollutants PAHs was carried out by Nunez et al. [93] and is shown in Eigure 1.15. 

Similar good results of the separation of aromatic and aliphatic hydrocarbons were recently obtained with ethyl(2-hydroxyethyl)dimethylammonium Ws(trifluoromethylsulfonyl)imide, [(Cj)2C2HOC2N][Tf2N], at 298.15 K [160]. The separation of m-xylene from n-octane by extraction with [(Ci)2C2HOC2N] [TfjN] was observed with the distribution ration of 0.3 and selectivities of range 22-31. The other ammonium salt as [(Ci)2C4HOC2N][Bp4] or 1,3-dihexyl-oxymethyl-imidazolium tetrafluoroborate was not so successful in this separation [161]. 

A coordination polymer such as (65) proves to have exemplary thermal and chemical stability and it has been used as the solid phase for separating a variety of aliphatic and heterocyclic bases. Retention volumes remained constant after many hours use at 100 °C.98... 

In a quite different field, that of petroleum chemistry, solvent extraction is being used extensively for the separation of aromatic and aliphatic hydrocarbons. The preferred solvents are all very polar sulfolane (Beardmore and Kosters 1963), dimethylsulfoxide, and N-methylpyrrolidinone. The polar solvents (Tables 3.5 and 4.3) have a higher affinity to the aromatic hydrocarbons and remove them from the mixture. Additional features in favour of, e.g., sulfolane,... 

The XAD-8 resin separation of hydrophobic and hydrophilic components of WSOM was also employed by Sannigrahi et al. (2006). The 13C-NMR results indicated that WSOM in urban atmospheric particles is mostly aliphatic in nature (-95% C mass) with major contributions from alkyl and oxygenated alkyls (-80%), carboxylic acid (-10%), and aromatic functional groups (-4%). The authors also found that urban aerosol WSOC are only qualitatively similar to aqueous humic material in terms of functional group distribution. 

Borecky, J., Gasparic, J., and Vecera, M., Identification of organic compounds. XXV. Identification and separation of aliphatic Ci-C18 alcohols by paper chromatography, Chem. Listy, 52, 1283, 1958 Chem. Abs., 53, 8039h, 1958. 

Most frequently, the capillary electrochromatography system is equipped with a UV detector, so it is not surprising that — to the best of our knowledge — no paper dealing with the separation of aliphatic hydrocarbons has been published so far. On the other hand, quite a few reports deal with the separation of polyaromatic species. Nearly always the packing used is ODS and most of the separations are run isocrati-cally. 

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