DuPont packed columns

A stainless steel column (4.6 mm internal diameter by 250 mm length) packed with 7 micron Zorbax ODS (Dupont) was equilibrated with 82 % Acetonitrile in water at a flow rate of 2.0 ml/min. provided by a Spectra Physics Model 87(X) pump and controller. The effluent was monitored at 230 nm using either a Tracor UV-Visible detector Model 970A or a Jasco Uvidec UV detector Model 1(X)-V. Peaks were recorded and calculated on a SpectraPhysics recording integrator. Model 4200 or Model 4270. Samples of 0.5 mg/ml in toluene were applied to the column automatically with a Micromeritics Autosampler Model 725 equipped with a 10 pi loop. 

High-Performance Liquid Chromatography. A Varian 5060 delivery system was used for this work with detection by UV absorption. Either a Varian UV-50 variable wavelength detector or a Hewlett Packard 1040A scanning diode array detector was used. All HPLC columns were packed in our laboratory (10) with 5-/um particle size Spherisorb-ODS, Spherisorb-CN (Phase Separations), or 8-pm particle size Zorbax-CN (Dupont Ltd). HPLC columns (20 or 25 cm X 4.6 mm i.d.) were coupled via short lengths of stainless steel capillary tubing (5 cm X 0.25 mm i.d.). Separation conditions were as follows ... 

A commercially packed h.p.l.c. column (25 cm x 4.6 mm) of y-aminopropyl silanised silica [e.g. 5/mi Spherisorb (Regis Chemical Co.), or 7/im Zorbax (Dupont Co.), or 10 /im Lithosorb (Merck), or 5 m irregular (J. T. Baker Chemical Co.)] was sequentially treated, at a pumping rate of 2 ml/min, with the following solutions 2 ml of triethylamine in 40 ml of dry tetrahydrofuran, 2g of (R)-JV-(3,5-dinitrobenzoyl)phenylglycine in 40 ml of dry tetrahydrofuran, 20 ml of dry tetrahydrofuran, and finally 10 per cent propan-2-ol in hexane, until the base line stabilises. The chiral amino acid derivative (which is available from Aldrich Chemical Co.) becomes ionically bonded to the amino residues on the stationary phase. 

Apparatus Use a suitable high-performance liquid chromatography system (see Chromatography, Appendix IIA) equipped with a dual wavelength detector system such that the effluent can be monitored serially at 254 nm and 325 to 385 nm (wide-band pass). Use a 1-m x 2.1-mm (id) column, or equivalent, packed with a strong anion-exchange resin (Dupont No. 830950405, or equivalent). 

Figure 32-11 Typical applications of bonded-phase chromatography, (a) Soft-drink additives. Column 4.6 X 250 mm packed with polar (nitrile) bonded-phase packing. Isocratic elution with 6% HOAc/94% H,0. Flow rate 1.0 mL/min. (Courtesy of BTR Separations, a DuPont ConAgra affiliate.) (b) Organophosphate insecticides. Column 4.5 X 250 mm packed with 5-/xm Cj bonded-phase particles. Gradient elution 67% CH30H/33% H.O to 80% CH,OH/20% H2O. Flow rate 2 mL/min. Both used 254-nm UV detectors.

Method 5001. An air volnme of 15-200 L may be passed throngh a glass fiber filter at a flow rate of 1-3 L/min. The phenoxy acid anions are desorbed with methanol and analyzed by HPLC with UV detection. The eluants nsed 0.001 M soln-tions of NaC104 and Na2B407. A stainless steel column packed with Zipax SAX (DuPont) is used for separation. The UV detector is set at 284 nm for 2,4-D and at 289 nm for 2,4,5-T. 

The silica-based SEC packings which are currently being employed were Introduced on the market in 1980 and there has since been very little improvement In their properties in terms of pore size distribution, particle size etc. Now, initiated by theoretical Investigations of the resolution of SEC columns, a new family of SEC packings Is beginning to be produced and marketed. The new packings are characterized by a particle size smaller than 5 / m, adequate porosity, and superior bonding chemistry. The Bio-Series 6F 250 column from DuPont de Nemours Is a typical example. However, the performance - with reference to resolution, analysis time and peak capacity — of this novel material has not yet been evaluated. 

Stainless-steel, 1000 X 2.1 mm (DuPont) first rinsed with tetrahydrofuran followed by vigorous cleaning of the inside of the tubing with a cotton string pre-soaked with THF. Chloroform is drawn through the column and the column dried under a stream of dry nitrogen. Bondapak C Corasil packing Mobile phase... 

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