Mobile phase solvent programmer

Mobile phase solvent A—acetonitrile solvent B—2mM KH2PO4. Equipment gradient system with solvent programmer and variable wavelength detector. 

There are two types of gradient programmer. In the first type, the solvent mixing occurs at high pressure and in the second the solvents are premixed at low pressure and then passed to the pump. The high pressure programmer is the simplest but most expensive as it requires a pump for each solvent supply. There can be any number of solvents involved in a mobile phase program, however, the majority of LC analyses usually require only two solvents but up to four solvents can... 

Figure 6. Effect of pH on anion exchange of IAA, Column — Vydac AX — TP (10p.m) 3.9 mm ID X 20 cm, flow = 2.0 cm3 min1, mobile phase = 0.1 m, Naff2P04 — Na HPO( buffer. Pump = Waters Associates 6000A, solvent programmer, Waters Associates 600.

Gradient elution separation the composition of the mobile phase is altered using a microprocessor-controlled gradient programmer, which mixes appropriate amounts of two different solvents to produce the required gradient. 

Dongjin Pyo also reported some other procedures The extraction by SFE was performed with a Beckman 116 pump (System Gold programmable solvent module 126), a 15 cm X 10 mm I.D. ODS column and Agilent HPLC 1100 series diode-array detector. Methanol/0.05 M phosphate buffer (52 48), pH 3, was used as a mobile phase at a flow rate of 2 mL/min. The analytical results obtained from real lake samples indicate the viability of the method for the determination of microcystins in real samples. 

The dried residues are repositioned in the workstation and resuspended with 100. 4L of mobile phase or a similar solvent. (7) After briefly vortexing, the completed plate is placed in the autosampler of the LC/MS instrument and between 1 and 10 lL of each utilized well is injected (unused wells can be skipped by the autosampler). Sample order can be easily randomized or otherwise sequenced by the programmability of the autosampler. 

The solvent programmer is an apparatus that allows the composition of the mobile phase to be changed, in a defined manner, over a defined period of time, and is normally controlled by the chromatograph computer. There are basically two types of gradient programmer, one that mixes the solvents at high pressure, prior to the column and the other that involves solvent mixing that occurs at low pressures, prior to the solvent pump. 

HPLC Analysis. A Tracor liquid chromatograph equipped with a Model 951 pump unit, a 980 A solvent programmer, a 970 A detector and a computing integrator Model CI-lOB (LDC-Milton Roy) are used for analysis. Alkaloids are finally separated by reversed phase HPLC carried out on a LiChrosorb Superspher RP-18 column (Merck, particle size 4 pm, 125 mm X 4mm i.d.) at 25 °C by the mobile phase 2-propanol-acetonitrile-water (5 40 50) with 1% ammonium carbonate (flow rate Iml/min, UV detector at 280 nm). 

A similar separation of a methylene chloride extract of PE was achieved by HPLC [16]. The solvent programmer is set to 90% from 100% heptane to 100% methylene chloride in 5 minutes. The total flow rate is 3 ml/min. The Model 450 UV detector is set at 0.2 or 0.4 absorbance unit sensitivity and the recorder chart speed is 1 cm/min. Duplicate injections of 100 pi of each of the standard and sample solutions are made. The mobile phase gradient is started at the point of injection. 

The type of separation desired dictates the choice ofthe mobile phase. Isocratic separations can be carried out with a single solvent or a fixed proportion mlxtmre of two solvents. For gradient elution, however, the development solvent composition changes continuously. This is achieved by a gradient programmer usualty attached to the HPLC assembty. 

Sander and Field (16) used a liquid chromatograph (solvent programmer in conjunction with two pumps) to generate a mobile-phase gradient. The eluent was introduced into the developer trough and distributed across the layer. 

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