Rheodyne injector

Chromatography conditions. HPLC was performed using a Milton Roy HPLC system (Riviera, FL, USA), consisting of a Constametric 3000 Series isocratic pump, a Rheodyne injector (Rheodyne L.P., Cotati, CA, USA), and a... 

Figure 4.11 (Continued) (B) The Rheodyne injector (Rheodyne, Inc.) in which the volume injected is determined by the sample loop. Sample loops can be obtained commercially in a number of fixed volumes or made to any size. (C) A 200-/xL loop.

The D4 content of the samples was determined by reverse-phase high-pressure liquid chromatography (HPLC) with a Varian 5500 liquid chromatograph. A DuPont Zorbax ODS (Cis) column was used with a Wilmad infrared detector set at 12.45 xm to monitor the Si-CHa vibration. The mobile phase was an 83 17 mixture of acetonitrile and acetone at a flow rate of 0.8 mL/min. A Rheodyne injector valve operating on compressed air was used with a 10-p,L sample loop for reproducible injection volumes. Ethyl acetate was used to dissolve the samples for analysis. 

Separations were performed on a Shimadzu HPLC instrument. A 50 pL aliquot was injected (in water acetonitrile 98 2 v/v) via a Rheodyne injector (Cotati, CA) onto a Vydac analytical column (4.6 cm x 250 mm) containing C-18 packing material (300A, 5 pm). Separations were achieved using a mobile phase of A) 0.06% TEA and B) 0.052% TEA in CH3CN. A solvent gradient of 2% —> 37.5% B (0-60 minutes) 37.5% 75% B (60-90... 

Analytical Detector, and a Rheodyne injector (SO-pL sample loop). The data acquisition system was a Chromate (Ver. 3.0 Interface Engineering, South Korea) installed in a PC. The flow rate of mobile phase was fixed at 4, 2, and 1 mL/min with CIM QA, QlOO, and HiTrap Q, respectively. The wavelength was fixed at 260 and 280 nm and the injection volume was fixed at 20 pL. The experiment was performed at room temperature. 

The HPLC system consisted of a Varian Model 5560 liquid chromatograph equipped with a constant-flow pump, a variable wavelength detector (Varian, Instrument Group/Walnut Creek, CA), a Rheodyne injector valve and an Alltech Spherisorb ODS column, 4.6 mm id x 25 cm (Alltech/Applied Science, IL). The mass spectrometer was a Finnigan Model 4600 quadrupole instrument with... 

MA.). The exclusion limit of this column system is 1.7 x 10° determined with polystyrene standards (Waters Assoc., Milford, MA). The HPLC system consists of a piston pump (mini-pump, Milton Roy Co., Hollywood, Fla.), the columns, a Rheodyne injector 7125 an R—U Differential Refractometer, and a Speedomax H recorder (Leeds and Northrop, Phila., PA), with THF as the eluant. 

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. 

The HPLC analyses were conducted with a Water 600 Pump apparatus. This apparatus was equipped with a quaternary solvent delivery system, a Rheodyne injector with 20qL sample loop and a UV detector Waters 486 Tunable which was fixed at 280 nm. Throughout this study. Alltech Intertsil ODS-5 C18 reversed phase column (150 mm, 4.6 mm, 5qm particle size) was used. The flow rate of the mobile phase was of 1 mL / min and the gradient elution was adapted from (Nakatani et al., 2000 Bouayed et al, 2007). The solvent composition and the gradient elution program are reported in the table 1. 

High precision autosampler, equipped with cooling if possible (e.g, Kontron 465) or manual Rheodyne injector with low dispersion volume and PEEK stator (e.g., Rheodyne 9125). 

HPLC syringe (this syringe incorporates a blunt end use of a beveled-end GC syringe would damage inner seals to the Rheodyne injector)... 

Countercurrent Chromatography Procedure. The entire column (pair of coiled multilayer columns connected in series) was filled with the stationary phase. The apparatus was then rotated counterclockwise at 600 rpm in planetary motion while the mobile phase was pumped into the inlet of the column at a flow-rate of 2.2 mL/min (head to tail elution mode). Maximum pressure at the outlet of the pump measured 80 psi. After a 1-hour equilibration period, the sample was loaded into the Rheodyne injector loop and injected. Effluent from the outlet of the column was continuously monitored with a Shimadzu UVD-114 detector at 312 nm and fractions collected with a Gilson FC-lOO fraction collector to obtain approximately 8.8 mL of eluant in each tube (during a 4-min interval). Retention of the stationary phase was estimated to be 930 mL (74%) by measuring the volume of stationary phase eluted from the column before the effluent changed to mobile phase (330 mL) and subtracting this volume from the total column capacity of 1260 mL. 

Before an extract is analysed, lOmL of n-pentane are used to flush the system and to adjust the solvent flow-rate to 0.5 mL/min. Extracts, concentrated to 200 pL, are injected with the Rheodyne injector. The fractions, determined from the calibration procedure (Table 20-2), are collected in 10 mL tapered, thick-walled test tubes with ground joints that... 

Figure 3 shows a schematic of the FIA system and details the thin-layer transducer cell, which contains the poly(3-methylthiophene) anion sensor electrode(s). Electrochemical detection in the amperometric mode was employed for the FIA/EC (flow injection analysis with electrochemical detection) studies. A typical potential used was +1.00 volts vs. Ag/AgCl reference electrode. The FIA-EC system consisted of an Altex lOOA double reciprocation pump and a Rheodyne injector (Cotai, CA) with either a 20 or 50 microliter sample loop. Constant potentials were applied using the herein described DWEP, which is software controlled. The electronically transduced signals are converted from analog to digital by use of A/D and D/A converter circuits. The option exists to automatically save the data on the computer or print the results as the experiment progresses. 

The HPLC separation was performed using a Waters 625 LC System (Milford, MA) connected to a Waters model 996 photodiode array detector, equipped with a Rheodyne injector (loop 50 pi) and a Waters Millenium workstation. 

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