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Reversed-phase liquid chromatography (RP-LC) is a mode of liquid chromatography in which non-polar stationary phase and polar mobile phases are used for the separation of organic compounds. [ 1 ] [ 2 ] [ 3 ] The vast majority of separations and analyses using high-performance liquid chromatography (HPLC) in recent years are done using the ...
This behavior is somewhat peculiar to normal phase chromatography because it is governed almost exclusively by an adsorptive mechanism (i.e., analytes interact with a solid surface rather than with the solvated layer of a ligand attached to the sorbent surface; see also reversed-phase HPLC below). Adsorption chromatography is still somewhat ...
The mobile phase consists of the sample being separated/analyzed and the solvent that moves the sample through the column. In the case of HPLC the mobile phase consists of a non-polar solvent(s) such as hexane in normal phase or a polar solvent such as methanol in reverse phase chromatography and the sample being separated. The mobile phase ...
In reversed phase the opposite is true; the stationary phase is nonpolar and the mobile phase is polar. Typical stationary phases for normal-phase chromatography are silica or organic moieties with cyano and amino functional groups. For reversed phase, alkyl hydrocarbons are the preferred stationary phase; octadecyl (C18) is the most common ...
Analysis of buprenorphine, a heroin substitute, demonstrated the potential utility of multidimensional LC as a low-level detection method. HPLC methods can measure this compound at 40 ng/mL, compared to GC-MS at 0.5 ng/mL, but LC-MS-MS can detect buprenorphine at levels as low as 0.02 ng/mL. The sensitivity of multidimensional LC is therefore ...
Hydrophilic interaction chromatography (or hydrophilic interaction liquid chromatography, HILIC) [1] is a variant of normal phase liquid chromatography that partly overlaps with other chromatographic applications such as ion chromatography and reversed phase liquid chromatography. HILIC uses hydrophilic stationary phases with reversed-phase ...
The researcher found that, in this case, reverse phase HPLC, was a better, more sensitive technique despite the time savings in direct injection. [21] Analysis of pharmaceuticals by MLC is also gaining popularity. The selectivity and peak shape of MLC over commonly used ion-pair chromatography is much enhanced. [22]
Around 90% of all pharmaceutical separations are performed on normal phase silica gel; however, other stationary phases such as alumina can be used for samples with dissociating compounds and cellulose for ionic compounds. [4] The reverse-phase HPTLC method (similar methodology to reverse-phase TLC) is used for compounds with high polarity.