Stationary phases in liquid chromatography

摘要: Although HPLC has only been available for fifteen years, the column part of system seen more changes than any other system. Classical chromatography was associated with large diameter, porous particle packings (>100 μm) in wide bore columns (1–2 cm i.d.) and a low head pressure (from gravity to 50 lbf in−2) which together lead slow analyses. The diameter particles are unsuitable owing diffusion into deeper pores causes decrease efficiency loss resolution. earlier packing materials also had very irregular shapes formed in-homogeneously packed beds producing great variation mobile phase velocity band spreading so that efficiencies resolution were again low. Equation (2.42) shows relationship between terms height equivalents theoretical plate many variables: $$H=C_{\text{D}}\prime\frac{D_{\text{M}}}{v}+C_{\text{S}}\prime\frac{d_{\text{f}}\,^{2}v}{D_{\text{S}}}+C_{\text{SM}}\prime\frac{d_{\text{p}}\,^{2}v}{D_{\text{M}}}+\frac{1}{1/C_{\text{F}}\prime d_{\text{p}}+D_{\text{M}}/C_{\text{M}}\prime v d_{\text{p}}\,^{2}}$$ (2.42) With LC regular adsorbents, d fthe film thickness stationary is equivalent p since porosity adsorbent allows solute diffuse through whole particle. Since C S, resistance mass transfer, proportional f 2 , S contributes linearly increase flow must be as small possible.