The liquid chromatography column uses sample processing and the preparation of the flow phase

Rrelevant topics liquid phase
chromatography
and gas chromatography technology chromat column
before use, it is best to carry out the performance test of the column, and save the results as a reference for future evaluation of column performance changes. However, it should be noted that the performance of the column may vary due to the differences in the sample, flow phase, column temperature and other conditions used, and in addition, in doing the column performance test is carried out in accordance with the conditions reported by the column factory (the conditions used for factory testing are the best conditions), only in this way, the measured results can be compared.1, sample pre-treatment:a, it is best to use the flow phase to dissolve the sample.b, the use of the treatment column to remove the strong polarity in the sample or with the column
fill
to produce irreversible adsorption of impurities.c, using 0.45 m of
filter
membrane filtration to remove particulate impurities.2, the preparation of the flow phase:liquid chromatography is the sample parts in the column filler and the flow phase quality exchange and achieve the purpose of separation, so the flow phase is required to have the following characteristics: a, flow relative to the sample has a certain ability to dissolve, to ensure that the sample parts will not be deposited in the column (or retained in the column for a long time).b, the flow phase has a certain inertness, and the sample does not produce
bio
bio-chemical reaction (except in exceptional circumstances).c, the viscosity of the flow phase should be as small as possible, in order to use a longer analysis column can get a good separation effect, while reducing the column pressure drop, extending the life of the liquid pump (can be used to improve the temperature method to reduce the viscosity of the flow phase).the materialized properties of the d and flow phases should be adapted to the detector used. If UV detectors are used, it is best to use solvents with low UV absorption.e, flow phase boiling point should not be too low, otherwise easy to produce bubbles, resulting in the experiment can not be carried out.f, after the flow is matched, must be degassed. Removing trace gases dissolved in the flow phase is beneficial for detection and prevents trace oxygen in the flow phase from acting on the sample.3, the choice of flow phase flow rate:because the column effect is a function of the linear flow rate of the flow phase in the column, different flow rate can be used to obtain different bar effect. For a particular column, the best flow rate is best used for the best bar efficiency. For columns with an inner diameter of 4.6mm, the flow rate is generally 1 ml/min, and for the inner diameter is 4.0mm columns, the flow rate is 0.8ml/min.the analysis time may be extended when the candidate is elected with the optimum flow rate. The washing strength of the flow phase can be changed to reduce the analysis time (e.g. when using inverse columns, the content of methanol or ethyl pyrol can be appropriately increased).note: . Because methanol is cheap, methanol systems are recommended for inverse columns (except where ethyl acetylene is required).b. For positive-phase columns recommended to use petroleum ether with a boiling range of 30 to 60 degrees C or purified hexane as a flow phase, hexane without purification shall not be used. Ultra-pure water (resistivity greater than 18 mega euros) is best used for water use, and deionized water and double steamed water contain phenolic impurities that may affect the results of the analysis. c. Water-containing flow phase is most likely to be made before the experiment, especially in summer using buffer solution as a flow phase not overnight. It is best to add sodium nitride to prevent bacteria from growing. d. Flow phase requires the use of 0.45 m membrane filtration to remove particulate impurities. . the use of HPLC-grade solvents to make flow phase, the use of suitable flow phase can extend the service life of the column, improve column performance.