Chromatography HPLC columns

Practical inlet systems for attaching a high-pressure liquid chromatography (HPLC) column to a mass spectrometer utilize atmospheric-pressure ionization (see Chapters 8 and 11). 

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)... 

Initially, progress in this area was hampered by the lack of suitable analytical methods for chiral hydrocarbons. Early studies relied on optical rotation to determine enantiomeric excess (ee) values, but with the development of chiral gas chromatography (GC) and high-performance liquid chromatography (HPLC) columns, chromatographic methods have become more common. 

A Zorbax-CN high performance liquid chromatography (HPLC) column used with hexane as mobile phase produced desirable results. Details of the HPLC procedure will be published elsewhere (5.). Three HPLC subfractions of S1-C2 were made ... 

In most common turbulent-flow chromatography experiments, a second conventional high-performance liquid chromatography (HPLC) column is employed. The conventional HPLC column, usually referred to as the analytical column, is used for peak sharpening and additional separation prior to MS detection. This approach requires an additional valve and pump to control the final HPLC separation. A typical dual-column methodology is shown in Fig. 10.5. 

The four common causes for high-performance liquid chromatography (HPLC) column failure include column clogging at the inlet frit (from samples/mobile phase), voids generated in the column, strongly adsorbed impurities from solvent/sample, and chemical attack of the stationary phase from the mobile phase or analytes. Procedure for removal of strongly adsorbed impurities from sample/mobile phase was discussed in Chapter 3, Section 3.9.2. 

The purity of crude peptide will be analayzed on a reverse-phase high-performance liquid chromatography (HPLC) column. The elution of the peptide is followed by absorbance recorded at 215 nm. The purification on a 10 to 20 mg scale is performed on a larger, preparative column monitored at the less sensitive wavelength of 238 nm. 

Various forms of solid-liquid) chromatography exist, including thin layer chromatography, column chromatography and, more recently, high performance liquid chromatography (HPLC). Column chromatography may be applied in... 

Many technical problems can occur with gradient elution, some of which can be avoided through various methods. To begin, gradient elution relies upon the purity of the solvents used. The high-performance liquid chromatography (HPLC) column can collect impurities. 

Trace enrichment is a sample precleaning procedure which is performed prior to a sample analysis. The purpose of any sample preparation procedure is twofold. First, such a procedure must selectively collect and concentrate the components of interest. Second, the method should eliminate any other components that would either interfere with the analysis or would contaminate an analytical gas chromatography (GC) or high-performance liquid chromatography (HPLC) column to shorten its useful analytical life. 

High-performance liquid chromatography (HPLC) Column chromatography in which the mobile phase is a liquid, often... 

One of the key issues in LC-MS involves separation of the analytes of interest from each other and from the matrix in which they are present. The introduction of the high-performance liquid chromatography (HPLC) column prior to the ionization source accomplished this task. The use of different stationary phases coupled with an appropriate selection of mobile phases and gradient conditions allowed for... 

The term H is usually determined for the last eluting compound. For a well-packed high-performance liquid chromatography (HPLC) column of 5-/xm particles H should be about 2 to 3 times the particle diameter. Values of 0.01 to 0.03 mm are typical. 

Desilylation of compound (28) gave compound (10) by using tetrabutylammo-nium fluoride in THF. The crude product was subjected to high performance liquid chromatography (HPLC) (column, microporasil 3 i.d. x 250 mm eluent, CHC1 flow rate, 0.5 ml/min.). Pure dehydropodophyllotoxin was found to be identical with compound (10) on direct comparison in all its spectral data. 

Purification schemes depend on the perceived nature of the impurities. The actual experimental conditions depend on the nature of the peptide. For each technique discussed, the user is encouraged to get in touch with the manufacturers of the media, high-performance liquid chromatography (HPLC) columns, equipment, etc. to acquire technical notes, which can provide very useful information on topics such as preparing media, solvent conditions, and HPLC strategies. 

In contrast to the expensive and short-lived high pressure liquid chromatography (HPLC) columns used for amino acid analyses, GC columns are extremely easy to maintain and very inexpensive to repack. 

In conventional high-performance liquid chromatography (HPLC), columns are usually of 10-25 cm length and 2—4 mm i.d. Recently, capillary HPLC columns have become available in the market. The terminology, abbreviations, and definitions have not yet been standardized. In the literature, we can find microbore, micro-LC, semimicro-LC,... 

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