Factors theoretical plates versus

Eigure 17-17. Theoretical plates versus retention factor for series of parabens separated by isocratic chromatography. Extra-column effects result in decreased efficiency for early-eluting components (low values of k). 

Figure 18.7 Influence of the sample size on the production rate of a preparative chromatographic column. Plot of the production rate per unit mobile phase flow rate, Pr/F , versus the loading factor, Lj2- Solid lines derived from Eq. 18.53a. Symbols from numerical solution of the equilibrium-dispersive model. Experimental conditions Column length 25 cm particle size 10 im efficiency 5000 theoretical plates. Isotherm coefficients ...

For the actual HPLC assay, equal volumes (about 20 p,l) of the standard preparations and the assay preparations are injected into the chromatogr h, the chromatograms recorded, and the peak responses measured. From the peak responses of the standard versus the assay preparations, the quantity, in mg, of rifampin (C43H5gN40i2) and isoniazid (C6H7N3O) in the product is calculated. If the assay is performed correctly, the relative retention times are about 2.6 and 1.0 for rifampin and isoniazid, respectively the column efficiency is not less than 50,000 and not less than 6000 theoretical plates for rifampin and isoniazid, respectively the tailing factors are not more than 2.0 and the relative standard deviation for replicate injections is not more than 2.0%. 

Fig. 27A, Height of a theoretical plate and pressure drop ofMellaiak 2X and 2Y versus flie factor...

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