HPLC, High performance reverse-phase

The problem of determining V-j in SEC is similar to that of determining zero retention time (tg) in other liquid chromatography columns. Recently, there have been several papers dealing with the determination of retention time of a retained peak in HPLC (12-19). In high-performance reversed-phase chromatography, McCormick and Karger (1 ) and Berendsen, et al., (16) have employed D2O to measure tg. Neidhart et al.,... 

Most HPLC is based on the use of so-called normal-phase columns (useful for class separations), reverse-phase columns (useful for homolog separations), and polar columns (used in either the normal- or reverse-phase mode). Since reverse-phase HPLC columns are generally easier to work with, almost all authors use high-performance reverse-phase liquid chromatography with octade-cyl chemically bonded silica as the stationary phase and nonaqueous solvents as mobile phases (so-called NARP, or nonaqueous reverse-phase chromatography). 

Recent progress in the high-performance liquid chromatography (HPLC) technique, e.g., developments in high-performance reversed phase columns and highly sensitive and specific detectors, has contributed to advances in... 

The application of HPLC to studies of BaP metabolism was an important advance (414). Using reverse-phase colunms, the major metabolites of BaP formed in vitro can readily be separated, as shown in Fig. 7. Systems for separation of the minor phenolic metabolites and for the triol and tetraol metabolites of BaP have also been developed (416, 506). Metabolites are quantified by ultraviolet detection or by scintillation counting of the column eluant. The latter technique is used for mixtures with low levels of metabolites and is more successful when unmetabolized BaP is first removed by silicic acid chromatography. Addition of vitamin E to incubation mixtures prior to analysis helps retard air oxidation (365). High-performance reverse-phase columns are commercially available and have relatively long lifetimes when used for this type of work. 

Chemical stabiUty studies are monitored by siUca gel thin-layer chromatography (dc) or by high performance Hquid chromatography (hplc) using a reverse-phase C g coated column (24). Hplc peaks or dc spots are visualized by thek uv absorption at 245 nm the tic spots can also be detected by ceric sulfate or phosphomolybdic acid staining. 

High-performance liquid chromatography (HPLC). see also Reversed-phase HPLC... 

HPLC, high performance (or pressure) liquid chromatography, is particularly suited for small water-soluble molecules and proteins. Most used for analysis of DNA fragments is the reverse phase HPLC. Detection with electrochemical detectors are preferred. There are many different brands of ECD detectors and electrodes/cells. In our laboratory we have found that the ESA Coulochem is working excellent for our purposes and provides excellent sensitivity. Similar experience with other detectors can be found. We have found that for HPLC-ECD analysis of urine, separation is critical due to electrochemically active peaks eluting close to that of 8-oxodG. Ways to detect a false peak is given in details elsewhere [3]. 

Figure 6-2 Chromatogram from an HPLC reversed-phase separation of tricyclic antidepressants with the use of a UV photometer detector set at 2l5nm. Signal is displayed at 0.1 AUFS, HPLC high-performance liquid chromatography UV, ultraviolet AUFS, absorbance units full scale. (Courtesy Vydac/The Separations Group, Hesperia, Calif.)...

High-performance liquid chromatography (HPLC) using the reversed phase technique is used to separate the most complex mixtures of organic and inorganic molecules with base-line separation quality. In the case of sulfur ho-... 

Assay Procedures. Tissues, feces, urine samples, and sample fractions were assayed for radioactivity (RA) by liquid scintillation counting essentially as described by Magnussen et al. (9). Tissues were assayed for parent tilmicosin by methanol extraction, purification by liquid-liquid partitioning, and measurement by high performance liquid chromatography (HPLC) on a reversed phase phenyl column with detection by UV absorption at 280 nm. Elution was with a nonlinear gradient of mobile phase consisting of water, acetonitrile, and dibutyl ammonium phosphate at pH 2.5. 

Analytical measurements for the determination and quantihcation of oxazole- and oxazine-related compounds in tobacco and tobacco smoke include gas chromatography (GC) with packed or capillary columns, high performance liquid chromatography (HPLC) usually with reverse phase (RP) columns, and mass spectrometry (MS) methods (GC-MSandLC-MS). 

Most common furanocoumarins have characteristic retention properties on HPLC (High Performance Liquid Chromatography) with both reversed-phase and conventional-phase columns (Spencer et al., 1987). The assignment of ring-substitution patterns of plant-derived furanocoumarins can be made by negative-ion mass spectrometry (Plattner and Spencer, 1988). 

Aberham A, Cicek SS, Schneider P, Stuppner H (2010) Analysis of sesquiterpene lactones, lignans, and flavonoids in wormwood (Artemisia absinthium 1.) using high-performance liquid chromatography (HPLC)-mass spectrometry, reversed phase HPLC, and HPLC-solid phase extraction-nuclear magnetic resonance. J Agric Food Chem 58 10817-10823... 

High-performance liquid chromatographic (HPLC) procedures using reversed-phase columns and detection by ultraviolet (UV) light, fluorescence detection (FED),... 

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