High-performance liquid chromatographic HPLC columns

Silica particles used for SPE sorbents are typically irregularly shaped, 40 to 60 pm in diameter. Silica particles used for sorbents in high-performance liquid chromatographic (HPLC) columns are generally spherical and 3 to 5 pm in diameter. Due to the differences in size and shape, SPE sorbents are less expensive than HPLC sorbents. Much greater pressures are required to pump solvents through the smaller particle sizes used in HPLC. 

In SFC, the mobile phase is delivered by a high-pressure pump. The sample is usually injected as a solution by means of a high-pressure injection valve. The column may either be a packed column, comparable to a high-performance liquid chromatographic (HPLC) column, or an open capillary column, comparable to a capillary gas chromatographic (GC) column, but with somewhat smaller internal diameters (50-100 / m). Detection is performed either on-line, (i.e., UV-VIS) or after the expansion of the fluid [i.e., flame ionization detection (FID) or mass spectrometry... 

Lambert, W. J., L. A. Wright, and J. C. Stevens. 1990. Development of a preformulation screen utilizing a C-18-derivitized polystyrene-divinylbenzene high-performance liquid chromatographic (HPLC) column. Pharm. Res. 7 577-586. 

It would appear that the sensitivity of the refractive index function was about 10 refractive index units and that of the UV absorption function about 0.001 absorption units. The cell volume was 12 il which is rather large to be used for modern high-performance liquid chromatographic (HPLC) columns. Nevertheless, the detector system is an interesting combination due to the fact that, together, the combined performance of the UV and refractive index detectors approach that of the universal detector. 

The volume of the cell was kept as small as possible to minimize band dispersion, but at the same time, the geometry of the flow cell had to provide optimum synchronization with the NMR sensing coil. Consequently, the walls of the cell had to be straight and parallel to the axis of the coil. the volume of the cell was about 420 pi (very large for high-performance liquid chromatographic (HPLC) columns) and thus, at a flow rate of 1 ml/min allowed a residence time of about 2 5 sec. To achieve adequate sensitivity, Fourier Transform techniques were employed. The layout of the system used by Bayer et al (1). is shown in Figure 2 and is fairly typical of all LC/NMR combinations. 

Applications and uses include the following medical implants, sealing rings, bearings, piston parts, pumps, high-performance liquid chromatographic (HPLC) columns, compressor plate valves, and cable insulation. 

Figure 9 shows the result of injecting 10 gA of the total low molecular weight fraction from GPC 1 (Column Code A2) into GPC 2 (Column Code Bl). With this column code, GPC 2 is performing as a High Performance Liquid Chromatograph (HPLC). Separation is based upon solubility (i.e. composition differences) rather than upon molecular size. Methyl methacrylate monomer was used as a reference and added to the solution injected into GPC 1. Concentrations of n-butyl methacrylate, styrene and conversion are readily calculated from the peak areas and initial concentrations. 

Reversed-phase high-performance liquid chromatography (HPLC) column 50 mm x 3.2-mm i.d. with Kromasil 5- um Gig packing High-performance liquid chromatograph coupled to a triple-quadrupole mass spectrometer with an atmospheric pressure chemical ionization (APCI) source Gel permeation chromatograph with a 60 mm x 25-mm i.d. column packed with Bio-Beads SX-3 (50-g)... 

High Performance Liquid Chromatographic (HPLC) Analysis. A Waters HPLC system (two Waters 501 pumps, automated gradient controller, 712 WISP, and 745 Data module) with a Shimadzu RF-535 fluorescence detector or a Waters 484 UV detector, and a 0.5 pm filter and a Rainin 30 x 4.6 mm Spheri-5 RP-18 guard column followed by a Waters 30 x 3.9 cm (10 pm particle size) p-Bondapak C18 column was used. The mobile phase consisted of a 45% aqueous solution (composed of 0.25% triethylamine, 0.9% phosphoric acid, and 0.01% sodium octyl sulfate) and 55% methanol for prazosin analysis or 40% aqueous solution and 60% methanol for naltrexone. The flow rate was 1.0 mL/min. Prazosin was measured by a fluorescence detector at 384 nm after excitation at 340 nm (8) and in vitro release samples of naltrexone were analyzed by UV detection at 254 nm. 

Initially, progress in this area was hampered by the lack of suitable analytical methods for chiral hydrocarbons. Early studies relied on optical rotation to determine enantiomeric excess (ee) values, but with the development of chiral gas chromatography (GC) and high-performance liquid chromatography (HPLC) columns, chromatographic methods have become more common. 

A review of high-performance liquid chromatographic (HPLC) instrumentation, techniques, and methodologies for the determination of trace organic compounds in water is presented. The review includes approaches to sample cleanup or analyte isolation for those compounds likely to be candidates for analysis by HPLC. Column technology, as it contributes to the use of HPLC for trace organic analyses, is discussed. Finally, various techniques for quantitative and qualitative detection of analytes are discussed. 

High-performance liquid chromatograph (HPLC e.g., Waters Chromatography) equipped with column heater, solvent pump, UV detector (set at 210 nm), integrator, autosampler, and (for manual injection) a 10-pl sample loop 15 x 0.46-cm YMC-ODS-AQ analytical column (AQ12S031546WT, Waters Chromatography)... 

Amadori compounds (N-substituted-l-amino-l-deoxy-2-ketoses) are potential precursors to the formation of many of these heterocyclic volatile products. The secondary nitrogen in most Amadori compounds is weakly basic and is therefore a likely site for rapid nitrosation reactions via normal reactions with nitrous acid, under mildly acidic conditions. However, purified Amadori compounds are usually obtained only after tedious isolation procedures are invoked to separate them from the complex mixtures of typical Maillard browning systems. Takeoka et al. ( 5) reported high performance liquid chromatographic (HPLC) procedures to separate Amadori compounds in highly purified form on a wide variety of columns, both of hydrophilic and hydrophobic nature. They were able to thus demonstrate that reaction products could be followed for kinetic measurements as well as to ensure purity of isolated products. 

There is no doubt that the combination of high-performance liquid-chromatographic (HPLC) separations with MS affords one of the most powerful, centrally applied tools in drug discovery and development [2]. While there is a clear trend toward incrementally smaller ID columns from the... 

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