High-pressure liquid chromatography detector system

High pressure liquid chromatography (HPLC) was used for the quantitative measurement of quinones and hydroquinones in the cultures. 20 pi of supernatant were injected in a Merck-Hitachi HPLC system 655A-12 equipped with a 4.6 x 250 mm Nucleosil C18 column (5 pm, RP 18). The system was run at a flow rate of 1 ml min-1 with a methanol/water gradient (10 to 20% methanol in 15 min, then 20 to 100% methanol in 5 min). The UV detector was operated at 281 nm or 275 nm to follow the reduction of quinones 13 and 14, respectively (37). 

Fig. 14.8 A thin-layer cell for use as a high pressure liquid chromatography electrochemical detector (courtesy of Bioanalytical Systems).

High pressure liquid chromatography (HPLC) was used to identify phenols and separate the products of the reaction. The system included a Dupont 870 pump module, 850 absorbance detector, and a 4.6 mm x 25 cm Zorbax ODS liquid chromatography column (all from DuPont and Co., Wilmington, DE). Analysis of 2-CP was achieved under the following conditions mobile phase 33% MeOH in water at 1.5 mL/min PCP analysis mobile pliase 50% MeOH in water at 1.5 mL/min UV detection for 2-CP and PCP at 254 nm. 

Inc. System (two model 6000A pumps model 440 UV detector with a 254 filter model 680 gradient controller model 746 data module and a RCM 8 X 10 cm Radial Compression Cartridge Holder) was used for high pressure liquid chromatography. Injections were made with a model 7125 Rheodyne injector. 

Aminosalicylic acid in assessment of reactive oxygen species formation by in vitro Fenton and ozonation reactions and by in vivo ozone-exposure experiments in rats revealed oxidation products as follows salicylic acid, by deamination 2,3-dihydro-xybenzoic acid and 2,5-dihydroxybenzoic acid, from radical or enzymatic hydroxylation 5-amino-2 - hydroxy-N,W-bis(3 - carboxy- 4- hydroxyphenyl)-1,4-benzoquinonediimine, a condensation product of oxidised 5-aminosalicylic acid and 5-amino-2,3,4,6-tetrahydroxybenzoic acid, attributed to hydroxyl radical attack without deamination, identified by high-pressure liquid chromatography electrochemical detector system analysis and by gas chromatography-mass spectrometry analysis of trimethyl silyl derivatives (Kumarathasan et al. 2001). 

High pressure liquid chromatography (HPLC) Waters (Mildford, MA) 6000A solvent delivery system, fitted with a Rheodyne injection valve and equipped with a Waters 484 tunable absorbance detector. 

The major application of porous, three-dimensional electrodes has been in metal removal from dilute process liquors (Chapter 7) although inorganic and organic dectrosynthesis applications continue to be explored (see, for example, the Dow-Huron cell for production in Chapter S). Many battery and l el cell electrodes utilize an active material which is (or is supported by) a porous, three-dimensional matrix (Chapter 11), while miniature porous electrodes have found use in electrochemical detector systems for high-pressure liquid chromatography analysis (Chapter 12). 

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. 

High-Pressure Liquid Chromatography. - A new sensitive, selective amperometric detector has been developed, based on the oxidation in alkaline solutions of carbohydrates on a glassy carbon electrode onto which has been cast copper/copper oxide particles dispersed in a Nafion film. This system substantially lowers the overpotential for oxidation. Its use was demonstrated for the quantitation of various aldoses, sugar alcohols, and disaccharides in h.p.l.c. and flow injection analyses. ... 

It is for these reasons that a recommendation is made to avoid, wherever possible, concentration and cleanup steps that involve "column chromatography" of this nature, that is, chromatography where an in-line detector is not involved. This distinction is made to eliminate any implied criticism of instrumented high pressure liquid chromatographic systems which have not to date been used extensively for this particular purpose. 

Apparatus (See Chromatography, Appendix IIA.) Use a high-performance liquid chromatograph operated at room temperature with a 10-p.m particle size, 30-cm x 4-mm (id), C18 reverse-phase column (jxBondapak C18 column, Waters Corp., 34-T Maple Street, Milford, MA 01757, or equivalent). Maintain the Mobile Phase at a pressure and flow rate (typically 2.0 mL/min) capable of giving the required elution time (see System Suitability in High-Performance Liquid Chromatography). Use an ultraviolet detector that monitors absorption at 254 nm (0.2 to 0.1 AUFS range). 

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