Column thermostat

The application of HPLC in routine environments, like pharmaceutical, food, or environmental analysis and particularly quality assurance, makes not only great demands on the robnstness of HPLC hardware, comprising pumps, column thermostats, and detection units, bnt in addition to the column reproducibility. Column reproducibility can be investigated at different levels of complexity Run-to-run reproducibility compares consecutive chromatographic runs, whereas long-term stability describes the column variance over several hundreds of injections. Column-to-column (batch-to-batch) reproducibility finally explores the match of independently fabricated chromatographic columns. Column characteristics that are routinely consulted for the determination of the robustness are retention, selectivity, column efficiency, and peak symmetry. 

The experimental simplicity the common instruments can be utilized, preferably but not necessarily equipped with the column thermostat. An additional injecting valve can be easily mounted between the sample injector and the LC LC column in case of the LC LC procedures, which apply the zone of the barrier liquid injected in front of sample. 

Column thermostats are required to maintain a constant temperature ( 0.1 °C) in both time and space. Differences in temperature between the mobile phase entering... 

Reducing the pathway length between LC and MS starts already with setting up your UHPLC instrumentation. The conventional LC setup typically follows a top-down path of your mobile phase (Figure 1.7a) with the solvent bottles on top, the stack sequentially contains the degasser, the pump, the autosampler, the column thermostat, and finally the detector(s) downstream. Most of all commercial mass... 

Temperature increase always helps for a kinetic optimization of separations (it does, however, require prerequisites regarding the column thermostatting and stationary phase temperature stability). 

This consideration on frictional heat effects is only applicable in this simple form, if the thermostatting of the column follows the so-called isothermal concept, in other words the thermostat attempts to keep the column at a defined temperature by removing the frictional heat. The larger the column diameter the more difficult it is to complete heat dissipation. Alternative to the removal of frictional heat is the adiabatic column thermostatting [4] where in the ideal case the column would be thermally insulated and all frictional heat remains in the column. Thermostats without a fan for heat circulation come closer to this adiabatic mode... 

The accessible range of temperature variation on common LC columns (using a column thermostat that allows working at subambient temperature) is approximately 10-50 °C. In this span, the retention factor can be changed by not much more than factor 2. 

PLA was determined by reversed-phase isocratic HPLC. The HPLC system consisted of a JASCO (Tokyo, Japan) AS-2055 autosampler, a PU-2080 pump, a CO-2060 column thermostat, an FP-2025 fluorescence detector and 807-IT integrator. The column used was of Cosmosil 5C18MS-II column (250 cm X 4.6 cm Nacalai Tesque, Kyoto, Japan). The mobile phase buffer was 20 mM potassium phosphate, pH 7.0, containing 10% (v/v) methanol. The flow rate, sample volume and column temperature were 0.5mL/min, 100 pL and 20 °C, respectively. The fluorescence intensity of the eluted 4-PLA was monitored at 430 nm (excitation at 360 nm). 

Amsterdam, The Netherlands) with 3.5- r,m particles (2008-2009 series). The pie-colunm used in both series was a 4.0 x 2.0 nun i.d. Phenomenex Security Guard colunm (Bester). The colunms were conditioned in a column thermostat that was maintained at a temperature of 21°C. The extract (20 p.L) was injected into the LC system and the analytes were separated using a linear gradient elution. 

Configuration of a method development system Autosampler Quaternary pump Photodiode array detector Column thermostat Switching valve/solvent (6 positions) Switching valve/columns (6 positions) Autosampler Quaternary pump Photodiode array detector Column thermostat Switching valve/solvent (12 positions) Switching valve/columns (6 positions) Autosampler at present, binary pump Photodiode array detector Column thermostat Switching valve/solvent (plan 12 positions) Switching valve/columns (12 positions)... 

Therefore, it was considered how more than two chromatographic factors, e.g. stationary phase, column temperature, gradient run time, solvent, gradient rise, etc., could be tested systematically in one experiment. With column thermostats, which were specifically developed for this purpose (Model H ELIOS, AnaConDa), a maximum of twelve columns and an arbitrary number of temperatures can be... 

The HPLC system that is to be used for such a imiversal development of a chromatographic separation method consists in the optimal case of a quaternary pump with a solvent switching valve (6-12 positions), an autosampler, a programmable column thermostat (for 6-12 columns), a photodiode array detector and other detectors, depending upon the need. A personal computer with suitable software is needed for the automatic control system. The method development software controls the HPLC system via this software and produces the chromatograms necessary for development and optimization. 

Apparatus involving a column thermostatically controlled within the range 0°C to 130 C and a katharometer at room temperature. This apparatus is used for separating mixtures when the highest boiling constituent boils below 160°C at atmospheric pressure. If die polymer constituent boils between 160 and 250 C then the column should be thermostatically controlled in the range 100 - 200 C. 

Employ a HPLC column thermostat Optional Essential... 

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