High-pressure liquid chromatography reverse-phase solvents

Oxyphenbutazone, and other non-narcotic analgesics are screened by reverse-phase high-pressure liquid chromatography (39). The column is LiChrosorb RP8 and the mobile phase is a acetonitrile-water mixture. Blood and organs are homogenized in 4% perchloric acid before extraction with the solvents. Urine is extracted without primary treatment. 

The quantitative analysis of the fat-soluble vitamins (A, E, D and K) and their esters by reversed-phase partition in water/alcohol solvents on Zipax columns has been reported [255]. The applicability of gas and high pressure liquid chromatography of vitamin A was discussed by Vecchi, Vesely and Oesterhelt [256] who concluded that HPLC was superior in this application. 

Reverse phase, C-18. This coating consists of 0.05 mm diameter porous glass beads with a layer of octadecylsilane bonded to the surface. The purpose of the coating is to duplicate as closely as possible the column conditions for high pressure liquid chromatography (HPLC) regarding the solvent selection. TLC is much faster than HPLC but is difficult to quantitate. These plates contain 19 rows of 1 cm x 20 cm. 

Isolation of potential anticancer compounds from bioactive extracts involves bioactivity-guided fractionation. The DNA-damaging natural products encountered in our studies were extracted by MEK and/or methanol, and the general methodology which we have employed in our bioassay-directed fractionation of these extracts is schematically presented in Fig. 7. These fractionations involved solvent-solvent partition, Sephadex LH-20 gel filtration, normal phase and reversed-phase (RP) column, preparative thin-layer and high pressure liquid chromatography (HPLC). Silica gel chromatography was employed only if bioactive compounds were found to be stable under these mildly acidic conditions. 

Total tin present as chloride or chloro complexes in urine can be analyzed by reversed phase high-pressure liquid chromatography (HPLC) and detected by ETAAS [98]. Tri-, di-, and monobutyltin can be extracted with ethyl acetate from the homogenized tissues acidified with HCl. Organotin compounds are separated on a silica gel column and then eluted with various solvent mixtures. The confirmation of each tin compound in the different fractions is carried out by flameless AAS and by chromatography. The detection limit is 1.5 ng of tin for each of the tin compounds [99]. 

Some compounds can be easily detected by both CGC and high-pressure liquid chromatography (HPLC), for instance, cocaine, which has characteristic electron-impact mass and UV fluorescence spectra (Fernandez et al., 2009). Inert nonpolar or low-polar silicone phases have chromatographic features suitable for separation and analysis by CGC. In addition, dedicated base-treated stationary phases are now used to improve the identification and quantification of compoimds. HPLC analyses are done by reversed-phase elution with buffered water/organic solvent mixtures. In contrast, numerous native drags and almost all metabolites require chemical derivatization before analysis [e.g., with trifluoroacetic anhydride, A -methyl-7V-trimethylsilyltrifluoroacetamide, or iV-(r-butyldimethylsilyl)-Af-methyltrifluoroacetamide, which is usually used for cannabinoids] this improves the analytical performance of the method and drastically reduces the risk of misinterpretation and misidentification of the compoimds. 

High-pressure liquid chromatography Analysis was performed by reverse-phase utilizing a Waters Associates chromatograph equipped with 30 cm X 4 mm i.d. micro Bondapak C g columns with 254-and 280-nm detectors at a flow rate of 60 ml/hr, using water-acetonitrile-acetic acid as a solvent system. 

Details of apparatus and technical methods for high-performance (pressure) liquid chromatography for the separation of retinoids, in particular the type of stationary phase, the elution solvent, the use of a modifier, the reversed-phase technique and detection, have been summarized in a number of review... 

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