HPLC packings, evaluation

A variety of HPLC packing materials have been prepared and their chromatographic properties evaluated for separating amodiaquine and other basic dru using a single mobile phase. The three most promising packing materials are silica, a mercapto Pr modified silica and a sulfonic acid modification (39). 

Fig. 3-8. HPLC evaluation of a 250 x 4.6 mm i.d. analytical column packed with the selected dipep-tidic (5)-Glu-(5)-Leu-DNB CSP. Conditions mobile phase 20 % 2-propanol in hexane, flowrate 2.0 mL min, UV detection at 280 nm. (Reprinted with permission from ref. [86]. Copyright 1999, American Chemical Society.)...

Trisciani, A. and Andreolini, F, Evaluation of a micro-HPLC system dedicated to packed capillary column liquid chromatography, /. HRC CC, 13,270,1990. 

Kassel, D. B. Shushan, B. Sakuma, T. Salzmann, J. P. 1994. Evaluation of packed capillary perfusion column HPLC/MS/MS for the rapid mapping and sequencing of enzymatic digests. Anal. Chem., 66,236-243. 

The introduction of "fast HPLC" has proven to be particularly valuable in protein analysis. As stated earlier, assay time in RP-HPLC analysis of proteins is typically long compared to that for smaller organic molecules. We have evaluated the use of 0.6-cm ID x 4-cm columns packed with 3-um particles in the analysis of insulin by RP-HPLC for potency determination, related substances, and in peptide mapping (7). The use of the "fast column" allows considerable savings (40-60%) in analysis time, compared to the regular (0.46-cm ID x 25-cm) columns, without loss in resolving power. 

Fields reported that continuous silica xerogels prepared from potassium silicate solutions could be used as highly permeable support media, and exhibit reasonable chromatographic efficiency in HPLC [23]. Minakuchi et al. reported the preparation and evaluation of continuous porous-silica columns that provide a much higher column efficiency in HPLC than do conventional columns packed with particles [13-16,18], The monolithic columns prepared in a capillary can also be used in CEC. 

HPLC was used to evaluate the enantiomeric resolution of dihydrope-pidine enantiomers (including nimodipine), using phenylcarbamates of polysaccharides as a chiral stationary phase [35]. A column (25 cm x 4.6 mm) packed with the arylcarbamate derivatives of amylase, cellulose, and xylem was used. Detection was effected using polarimetry at 435 nm. Using xylem bis-(3,5-dichlorophenylcarbamate) and a mobile phase (flow rate of 0.5 mL/min) of 0.1%, diethylamine in hexane-propan-2-ol (17 3) yielded separation of nimodipine. 

All parameters of the packing material are interrelated in their influence on the chromatographic performance of the column. The quality of an HPLC column is a subjective factor, which is dependent on the types of analytes and even on the chromatographic conditions used for the evaluation of the overall quality. 

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