Mobile phase inorganic solvents used

Lambert and DeLeenheer (1992) contributed a review on the TLC analysis of K vitamins. They noted that although HPLC is usually the method of choice for analysis, there is some interest in HPTLC-densitometric analysis of the K vitamins. Their review covers isolation, extraction, and cleanup methods uses of polar inorganic solvents uses of modified silica (i.e., nonpolar bonded phases such as C2, Cg, C18, and phenyl) uses of mobile phases and methods of detection and quantification of the K vitamins. Madden and Stahr (1993) assayed vitamin K in bovine liver by reversed-phase TLC with dichloromethane-methanol (7 3)... 

For the size exclusion chromatography of proteins on silica-hased diol packings, it is generally recommended to use fully aqueous mobile phases with a salt concentration between 0.1 and 0.3 M. In general, a phosphate buffer around pH 7 is used as the mobile phase. Under these circumstances, the tertiary structure of most proteins is preserved without difficulty and the interaction of proteins with each other is minimized. However, other inorganic buffers or combinations of buffers with organic solvents can be used without difficulties for special applications. 

Involatile inorganic buffers, when used as mobile-phase additives, are the prime canse of blocking of the pinhole. The situation can be alleviated either by replacing them by a more volatile alternative, such as ammonium acetate, or by nsing post-colnmn extraction to separate the analytes from the buffer, with the analytes, dissolved in an appropriate organic solvent, being introduced into the mass spectrometer. 

The selection of proper mobile phase in TLC exerts a decisive influence on the separation of inorganic ions. With a particular stationary phase, the possibility of separation of a complex mixture is greatly improved by the selection of an appropriate mobile phase system. In general, the mixed aqueous-organic solvent systems containing an acid, a base, or a buffer have been the most favored mobile phases for the separation of ionic species. The mobile phases used as developers in inorganic PLC include ... 

Silica stationary phases for exclusion can be used with either organic or aqueous solvents. Some types are bonded phases, others are unmodified. When aqueous phases are used with silica exclusion columns, small amounts of polar mobile phase modifiers (inorganic salts or polar organic solvents) often have to be used to reduce adsorption effects. 

The heterogenization of organometallic catalysts on inorganic or organic solids has been extensively studied with traditional organic solvents. Mass transfer limitations and metal leaching have been identified as major obstacles for the practical use of this approach. Both factors might be reduced if an SCF is used as the mobile phase, albeit systematic studies are currently not yet available. 

Separation science focuses on room temperature ionic liquids (RTlLs), salts that are liquid at ambient temperature. They have been studied as extracting solvents, stationary and mobile phases, mobile phase additives, and other uses. Common RTILs consist of a bulky nitrogen- or phosphorus-containing organic cation (pyridinium or pyrrolidinium, alkyl-imidazolium, ammonium or phosphonium) and a variety of organic and inorganic anions (triflate, dicyanamide, trifluoroacetate, acetate trifluo-romethylsulfate, nitrate, perchlorate, bromide, chloride, chloroaluminate, tetrafluo-roborate, hexafluorophosphate). 

Reversed phase liquid chromatography (RPLC) allows the separation of analytes with different hydrophobicity and polarity characteristics. It has good selectivity mobile phases used in the technique contain organic solvents and small amounts of inorganic salts [149]. The effectiveness of the process depends on the hydrophobicity of the separated analytes. Charged substances must first be transformed into neutral derivatives (e.g., by adding appropriate anti-ions into the mobile phase). 

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