High-performance liquid chromatography injector

Fernandez Otero, G.C. Lucangioli, S.E. Carducci, C.N. Adsorption of drugs in high-performance liquid chromatography injector loops. J.Chromatogr.A, 1993, 654, 87-91... 

High Performance Liquid Chromatography. Tissue extracts were analyzed with a Varian model 5020 liquid chromatograph equipped with a Rheo-dyne model 7120 loop injector valve, a Tracer 970 variable wavelength detector set at 257 nm, an automated Hewlett-Packard 3385A printer-plotter system for determining retention times and peak areas, and a Waters /x Bondapak column (3.9 mm i.d. X 300 mm) for carbohydrate analysis. The buffer was eluted isocratically at 1 mL/min with a 1 4 (v/v) mixture of 0.01 M monobasic sodium phosphate (pH 4.46) and methanol. The minimum amount detectable was 10 ng. 

High-performance liquid chromatography employs very fine particles, and uses high-pressure pumps to force the mobile phase through the column. The mobile phase passes from a reservoir through the pump, an injector, the column and a flow-through detector to a waste collection reservoir. The injector allows the introduction of sample mixtures into the flowing mobile phase with little or no disturbance to the flow. 

High-performance liquid chromatography (HPLC) is a versatile analytical technique using sophisticated equipment refined over several decades. An in-depth understanding of the working principles and trends is useful for more effective application of the technique. This chapter provides the reader with a concise overview of HPLC instrumentation, operating principles, recent advances, and modern trends. The focus is on the analytical scale HPLC systems and modules (pump, injector, and detectors). System dwell volume... 

Sugars. The high performance liquid chromatography (HPLC) method described by Hunt et al. (8) was used to determine the sugars in the kiwifruit and nectars with some modifications (21). A Waters Association Chromatograph equipped with a Model 6000-A solvent delivery system, a Model R401 refractometer detector, a D6K universal injector column was a 30 cm x 4 mm i.d. stainless steel tube packed with u-bondapak-carbohydrate (Waters Associates). The precolumn was packed with CO-PELL PAC (Whatman). The eluent was acetonitril and distilled water (85/15, v/v). 

The LC system consisted of a Jasco 880 PU pump (JASCO, Tokyo, Japan) for the mobile phase, a Rheodyne Model 7125 injector with a 25 pL loop, and a 0.2 x 15 cm Mightysil RP-18 GP (5 pm) column (Kanto Chemical, Tokyo, Japan). LC was performed using an aqueous solution containing 80% MeCN as the mobile phase at a flow rate of 0.2 ml/min at 26°C. The column was connected to L-7455 diode array detector (Hitachi, Tokyo, Japan) with a flow cell (17.7 pL, 10 mm), and Hitachi D-7000 advanced high performance liquid chromatography (HPLC) system manager was utilized for data acquisition. 

The method of characterization by high-performance liquid chromatography [HPLC] is as follows 25 mg of hemicellulose was put into 50 mL volumetric flask and pure water was added to the mark. The mixture was shaken and then filtered [first few milliliters of filtrate was discarded]. The solution was then filtered through a membrane filter of 0.2 pm cellulose nitrate. Then about 100 mL solution was injected into the HPLC system via a loop injector with a 20 mL, using an isocratic elution system with distilled water with a mobile phase, flow rate 0.8 mL/min. The detection was made using a UV detector at a wavelength of 280 nm [34]. 

A typical high-performance liquid chromatography (HPLC) system consists of two pumps, a mixer, an injector, a guard colunm, a separation column, a detector, an electrospray nozzle, and a mass spectrometer. The two pumps and the mixer allow establishment of desired solvent gradients. The injector is used to inject a small amount of sample into the column. In all separation techniques, definition of a small volume of injected sample is cmcial in preventing adverse broadening of peaks and a consequent loss in compmient resolution. The injected compounds are separated in the separation colunm and then detected via a simple detector or a mass spectrometer. All of the parts of the HPLC system have been miniaturized, and several research groups have been able to demonstrate on-chip HPLC separations. 

The injector is an interface that achieves reproducible and accurate transfer of a sample volume between the system operator and the chromatographic column in a front (band) as narrow as possible. Usually, for analysis by high-performance liquid chromatography (HPLC), samples are prepared in a liquid state (as a solution in an appropriate solvent or mixture of solvents, obtained as a result of sample preparation of solid or liquid samples). For practical reasons (avoiding column overloading), even for analytes in a liquid state under ambient conditions, dilution in appropriate solvents is more often used. 

Loop Injectors for High Performance Liquid Chromatography (HPLC)... 

A typical high-performance liquid chromatography (HPLC) system consists of two pumps, a mixer, an injector, a guard column, a separation column, a detector, an electrospray nozzle and a mass spectrometer. The two pumps and the mixer allow establishment of desired solvent gradients. The injector is used to inject a small... 

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