Degassing systems, HPLC

A modern solvent delivery system consists of one or more pumps, solvent reservoirs, and a degassing system. HPLC pumps can be categorized in several ways by flow range, driving mechanism, or blending method. A typical analytical pump has a flow range of 0.001-10 mL/min, which handles comfortably the flow rates required for most analytical work (e.g., 0.5-3 mL/min). Preparative pumps can have a flow range from 30 mL/min up to L/m. 

Although the method is simple and straightforward, there are a few important points to consider. First, since 200 pL are being injected on to a 2-mm diameter HPLC column, compatible solvents must be injected on to the column and the amount of acetonitrile used in the prepared samples should be exactly as directed. Second, the temperature of the column and the use of a degassing system for the mobile phase are critical components required to guarantee reproducible chromatography. In addition, the standards should be stored in a refrigerator when not in use. 

Model RR/066 351 and 352 pumps models 750/16 variable-wavelength UV monitor detector 750/11 variable filter UV detector, MPD 880S multiwave plasma detector, 750/14 mass detector 750/350/06 electrochemical detector refractive index detector HPLC columns column heaters, autosamplers, pre-columns derivatization systems, solvent degassers, preparative HPLC systems... 

High Performance Liquid Chromatography (HPLC) (Chapter 30) gives an elaborate discussion of theoretical aspects. Instrumentation encompasses the various important components e.g., solvent reservoir and degassing system pressure, flow and temperature pumps and sample injection system ... 

Solvent Reservoirs. Storage of sufficient amount of HPLC solvents for continuous operation of the system. Could be equipped with an online degassing system and special filters to isolate the solvent from the influence of the environment. 

A modern HPLC solvent delivery system consists of one or more pumps, solvent reservoirs, and a degassing system. Typical requirements of an analytical HPLC pumps are ... 

The apparatus consists of a degassing system and a single pump, single wavelength detector HPLC the same as that described in Experiment 24, p. 579. 

Thermo SeparaAons Products HPLC system with an autosampler, solvent degasser and column heater interfaced to aFinnigan MAT 7000 mass spectrometer or equivalent insAumentation opAmized for the detection of azinphos-methyl. 

A simple system is comprised of an isocratic pump, a manual injector, a UV detector, and a strip-chart recorder. A schematic diagram of an HPLC instrument is shown in Fig. 15.4. This simple configuration is rarely used in most modern laboratories. A typical HPLC system is likely to consist of a multi-solvent pump, an autosampler, an on-line degasser, a column oven, and a UV/Vis or photodiode array detector all connected to and controlled by a data-handling workstation. Examples of modular and integrated systems are shown in Fig. 15.5. Some of the important instrumental requirements are summarized in Table 15.2. 

The traditional HPLC instrument is composed of two different parts the first part separates the components of the sample and the other part accomplishes the detection of the components separated. The part of the HPLC carrying out the separation contains a column, an injection device and the eluent delivery system (pump with filters, degasser and transfer tubing, eventually a mixer for gradient elution). One or more detectors, a signal output device coupled with appropriate software, are responsible for detection and primary data evaluation. Pumps deliver the eluent or the different components of the eluent into the column with a precise, constant and reproducible flow rate. 

HPLC system consisting of a buffer pump, preferably with degasser, autosampler with cooling system, fluorescence detector (excitation 384 nm, emission 516 nm) and an integration and data handling system. 

The HPLC system consist of an HP 1100 series binary gradient pump, a vacuum degasser, and a column temperature controller (all from Hewlett Packard), connected to a Gilson 231 XL autosampler (Gilson). 

Vacuum filtration device, ultrasonicator, or inline vacuum degasser HPLC system ... 

J,m poly(tetrafluoroethylene) (PTFE) syringe-tip filters High-performance liquid chromatography (HPLC) system equipped with Quaternary pump Diode array detector Vacuum degasser... 

The first step in the wetted path in the HPLC is the solvent reservoir holding freshly filtered (and possibly degassed or deoxygenated) solvent. Most systems use a porous fritted stone (5-30-/an filter) as a solvent line sinker. The tubing to the solvent inlet is wide-diameter Teflon . In the solvent inlet line we may have another frit and a sapphire ball/stainless steel check valve. The wetted surfaces in the pumping chamber are all stainless steel except for the plunger... 

This compound is determined using HPLC analysis. A Diluent reagent is prepared as a 9 1 mixture of water and methanol. The Mobile Phase is prepared as a filtered and degassed solution by dissolving 5.6 g of monobasic potassium phosphate in 820 mL of water in a 1-liter volumetric flask, adjusting with phosphoric acid to a pH of 4.3, diluting with methanol to volume, and mixing. Adjustments in the composition may be made if required by the System Suitability requirements. 

Sample analysis was performed by using an Applied Biosystems (Foster City, CA) API 3000 triple quadrupole mass spectrometer equipped with a TurboIonSpray source and an Agilent 1100 capillary HPLC system (Palo Alto, CA). The capillary HPLC system included a binary capillary pump with an active micro flow rate control system, an online degasser, and a microplate autosampler. The analytical column was a 300 pm I.D.x 150 mm Zorbax C18 Stablebond capillary column (pore size 100 A and particle size 3.5 pm). The injection volume was 5 pL, and a needle ejection rate of 40 pL/min was used. The pLC flow rate was 6 pL/min. In order to minimize dead volume before the column, the autosampler was programmed to bypass the 8 pL sample loop 1.5 min after injection. The mobile phase consisted of (A) 2 mM ammonium acetate (adjusted to pH 3.2 with formic acid) in 10 90 acetonitrile-water, and (B) 2 mM ammonium acetate in 90 10 acetonitrile-water. The percentage of mobile phase B was held at 32 % for the first minute, increased to 80 % over 8 min, and then increased tol00% over the following 1 min. 

The organic acids were analyzed with an HPLC system consisting of degassing unit (Gastorr GT-103),pump (Pharmacia LKB), autosampler (Pharmacia, LKB), precolumn (Shodex R Spak KC-LG), separation column (Shodex R Spak KC-811), water bath (Julabo U3) and a UV detector (Soma Optics LTD S-3702). The data monitoring was performed using a PC-chromatography data system Andromeda 1.6 (Techlab). 

---