Column packing, HPLC

Shodex Packed Columns for HPLC and Shodex Instruments for HPLC, 95/96, p. 10, Showa Denko. 

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.)...

As expected from the design of the experiment, the HPLC column packed with CSP 14 containing all 36 members of the library with tt-basic substituents separated 7t-acid substituted amino acid amides. Although encouraging since it suggested the presence of at least one useful selector, this result did not reveal which of the numerous selectors on CSP 14 was the most powerful one. Therefore, a deconvolution process involving the preparation of series of beads with smaller numbers of attached selectors was used. The approach is schematically outlined in Fig. 3-17. 

High-pressure pumps operating at up to 6000 psi are required to force solvent through a tightly packed HPLC column, and electronic detectors are used to monitor the appearance of material eluting from the column. Alternatively, the column can be interfaced to a mass spectrometer to determine the mass spectrum of every substance as it elutes. Figure 12.18 shows the results of HPLC analysis of a mixture of 10 fat-soluble vitamins on 5 jam silica spheres with acetonitrile as solvent. 

Dichloromethane (unstabilized HPLC grade) was purchased from Fisher Scientific and was dried by percolation through two columns packed with neutral alumina under a positive pressure of argon. 

Packed column An HPLC column containing particles of inert material of typically 5 ttm diameter on which the stationary phase is coated. 

Reversed-phase high-performance liquid chromatography (HPLC) column 50 mm x 3.2-mm i.d. with Kromasil 5- um Gig packing High-performance liquid chromatograph coupled to a triple-quadrupole mass spectrometer with an atmospheric pressure chemical ionization (APCI) source Gel permeation chromatograph with a 60 mm x 25-mm i.d. column packed with Bio-Beads SX-3 (50-g)... 

Second cleanup Transfer the above carbon tetrachloride solution into a glass column packed with 7 g of silica gel saturated in carbon tetrachloride. Rinse the column, first with 2 mL of carbon tetrachloride and then with 35 mL of hexane-ethyl acetate (17 3, v/v). Elute benfuracarb with 30 mL of the same hexane-ethyl acetate solution. Concentrate the eluate to near dryness by rotary evaporation and prepare the GC/HPLC-ready sample solution by dissolving the residue either in benzene for plant material or in acetonitrile for water and soil. 

Transfer the residue on to the top of the column packed with 10 g of 5% water containing Horisil PR with the aid of hexane. Rinse the column with 95 mL of hexane and then with 100 niL of acetone-hexane (1 99, v/v). Discard the column washings. Elute hexythiazox with another 150 mL of acetone-hexane (1 99, v/v) in a 300-mL round-bottom Aask and concenAate the eluate to near dryness by rotary evaporation at 40 °C. Prepare the HPLC-ready sample soluAon by dissolving the plant material residue in acetonitrile. 

Wilson, T. D. and Simmons, D. M., A particle size distribution analysis of used HPLC column packing material, Chromatographia, 35, 295, 1993. 

A polyethylene-coated (PEE) silica column was used with water-methanol eluents to achieve the separation and retention of 27 pesticides.40 The retention times of 33 commercial pesticides were determined on an octadecyl (ODS)-derivatized alumina column using water-methanol eluents and compared with retention properties on an ODS-silica column packing.41 More recently, RP-HPLC was used in combination with diode array detection for the identification and quantification of 77 pesticides (acidic, basic, and neutral) in groundwater samples.42... 

Kirkland J.J., Henderson J.W., Martosella J.D., Bidlingmeyer B.A., Vasta-Rus-sell J., and Adams Jr. J.B., A highly stable alkyl-amide silica-based column packing for HPLC of polar and ionizable compounds, LC-GC, 17 (7), 634,1999. 

Detector selectivity is much more important in LC than in GC since, in general, separations must be performed with a much smaller number of theoretical plates, and for complex mixtures both column separation and detector discrimination may be equally significant in obtaining an acceptable result. Sensitivity is important for trace analysis and for compatibility with the small sizes and miniaturised detector volumes associated with microcolumns in LC. The introduction of small bore packed columns in HPLC with reduced peak volume places an even greater strain on LC detector design. It is generally desirable to have a nondestructive detector this allows coupling several detectors in series (dual... 

---