How to choose the mobile phase of high performance liquid ch
As the mobile phase in high performance liquid chromatography is liquid, it has affinity for components and participates in the competition of fixed relative components. Therefore, the correct choice of mobile phase directly affects the separation of components. The requirements for mobile phase solvent are as follows:(1) The solvent must have suitable polarity and good selectivity for the sample to be tested.
(2) The solvent should match the detector. For UV absorption detector, the wavelength of detector should be longer than the UV cutoff wavelength of solvent. The so-called ultraviolet cut-off wavelength of solvent refers to that when the radiation less than the cut-off wavelength passes through the solvent, the solvent will produce strong absorption of the radiation. At this time, the solvent is regarded as optically opaque, which seriously interferes with the absorption measurement of components. You can search the UV cut-off wavelength of solvents on the Internet.
For the refractive index detector, it is required to select the solvent which is different from the component refractive index as the mobile phase to achieve the highest sensitivity.
(3) High purity. Due to the high sensitivity of HPLC, the purity of mobile phase solvent is also required. Impure solvents may cause baseline instability or "pseudo peaks". The existence of trace impurities will increase the cut-off wavelength by 50 ～ ioonm.
(4) Good chemical stability. It is not allowed to choose the solvent that reacts with the sample or polymerizes.
(5) Low viscosity. If high viscosity solvent is used, the pressure will be increased, which is not conducive to separation. The commonly used low viscosity solvents are acetone, ethanol, acetonitrile, etc. However, solvents with too low viscosity should not be used, such as pentane, ether and so on. They are easy to form bubbles in chromatographic column or detector and affect the separation
For more related technologies, please consult MS technologies technicians
