Simple sugars and lowermolecularweight oligomers

Sugar determinations are important in the food industry, in analysis of carbohydrates and their polymers, and in pharmaceutical analysis of glyco-proteins. A number of column types have been used in the separation of sugars, particularly amino columns and strong anion exchange columns. Amperometric detection is widely used, but post-column detection schemes, UV detection, and refractive index detection are also useful. Sugars are capable of being linked together at a number of locations on the...

Carbohydrate polymers

Higher oligosaccharides occur as natural homopolymers, such as inulin, dextran, starch, and pullulan, and as heteropolymers, such as pectin and heparin. Complex oligosaccharides are found as N-linked or O-linked prosthetic groups of glycoproteins. As has been noted, analysis of the branching of polysaccharides is one of the most challenging problems in contemporary analysis. One means of approaching that problem is though enzymatic digestion with linkage-specific enzymes. In Figure 23 is shown...

Info

D., High-pressure liquid chromatography techniques for the isolation and identification of organics in drinking water extracts, J. Chromatogr. Sci., 16, 254, 1978. 64. Swadesh, J. K., Stewart, Jr., C. W., and Uden, P. C., Comparison of liquid chromatographic methods for analysis of homologous n-alkyl esters of biphe-nyl-4,4'-dicarboxylic acid, Analyst, 118, 1123, 1993. 65. Farinotti, R., Siard, Ph., Bourson, J., Kirkiacharian, S., Valeur, B., and Mahuzier, G.,...

Applications 541 Inorganic ions

For many applications, spectroscopic techniques such as atomic absorption spectroscopy are preferred for the determination of simple inorganic ions. For complex mixtures, for samples derived from complex matrices, or in cases when differentiation of oxidation states is required, ion exchange is usually superior. Prevention is critical for a number of industrial applications of ion exchange chromatography for inorganic ions, particularly in nuclear power. Applications are also to be found in...

Validation considerations

Validation activity is the crucial end-stage in the process development of a biopharmaceutical chromatographic purification and one which young companies often underestimate. Regarding process validation, the FDA issued a guideline in 1986 which states Process validation is establishing documented evidence which provides a high degree of assurance that a specific process will consistently produce a product meeting its predetermined specification and quality attributes. Validation is not...

A321 Theory

A model of blending aqueous salt buffers for chromatography has been developed.1 The model assumed full miscibility, low mixing enthalpy and low volume change. It reproduced experimental S-curves of buffer strength produced by a Pharmacia P3500 dual piston system equipped with a model 24 V dynamic mixer with 0.6 mL internal volume as well as those produced by a BioSepra ProSys 4-piston system equipped with two dynamic mixers of 1.2 mL internal volume. Separations in hydrophobic interaction...

Giddings Jc In Hplc References

R., and Horvath, Cs, An Introduction to Separation Science, John Wiley amp Sons, New York, 1973, 121-167. 2. Snyder, L. R. and Kirkland, J. J., Introduction to Modern Liquid Chromatography, Second ed., John Wiley amp Sons, New York, 1979, chap. 2. 3. Glajch, J. L., Kirkland, J. J., Squire, K. M., and Minor, J. M., Optimization of solvent strength and selectivity for reversed-phase liquid chromatography using an interactive mixture-design statistical technique, J....

Reversedphase HPLC update 2000

Ryall A4.1 Introduction Reversed-phase HPLC RP-HPLC continues to be the most popular chromatographic separation mode. A better understanding of the critical properties of chemically modified silica-based stationary phases has facilitated the preparation of more reproducible and rugged reversed phase column packings. Selecting the most suitable column available from among many different commercial suppliers remains a challenge to the chromatographer. Advances in the...

Crossover Of Peak Retention Times

0.0 0.2 0.4 0.6 0.8 1.0 Median Organic Composition Fraction Figure 4 Crossover of peak retention times as a function of gradient rate in the separation of peptides. Previously unpublished data are drawn from Swadesh, J. K., Tryptic fingerprinting on a poly styrene-divinyl benzene reversed phase column, J. Chromatogr, 512, 3215, 1990.92 0.0 0.2 0.4 0.6 0.8 1.0 Median Organic Composition Fraction Figure 4 Crossover of peak retention times as a function of gradient rate in the separation of...

Development of an RPLC method

Method development starts from an understanding of the physical and chemical properties of the sample molecule and or the impurities present i.e., the properties such as solubility, stability, polarity, dissociation constant, molecular weight, electroactivity, and the UV absorption spectrum . If the sample is of a low-molecular-weight lt 2000 and is soluble in the reversed phase water organic solvents, then RPLC is one of the methods of choice. Preliminary estimates of retention may be made on...

The Science

R-aud, complacency, and secrecy in the scientific establishment Figure 6 The Science Mob. Reproduced with permission from The New Republic and Mr. Robert Grossman.110 Figure 6 The Science Mob. Reproduced with permission from The New Republic and Mr. Robert Grossman.110 work discovered to be erroneous in a regulatory audit. The low rate of fraud or error in science is a powerful testament to the fundamental dedication and decency of the overwhelming majority of scientists. Still, some members of...

Cip

This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. Neither this book nor any part may be reproduced or transmitted in any form or by any...

A325 Chiral chromatography

Chiral chromatography has only rarely been used in preparative settings. There are a number of reasons for this. Only recently has it been fully recognized that optically pure compounds have potential benefits in lower toxicity and greater efficacy. Also, chiral synthesis represents an opportunity to reclaim what would be wasted if achiral synthesis were used in combination with chiral purification. The stationary phases used in chiral chroma-tography also tend to be expensive, of low capacity,...

Drugs pharmaceuticals and pharmacologically active compounds

Many, if not most, pharmacologically active compounds are amines. For this reason, issues in the RPLC of substances of pharmaceutical interest tend to be similar to those encountered in the separation of amines. Incompletely endcapped silica-based phases may exhibit tailing. The use of ion pairing or ion suppression is common in the analysis of pharmacologically active substances. Also, derivatization of the amine functionality prior to analysis may be required. The RPLC retention indices of...

Prediction of retention time

It is possible to predict retention times with a reasonable degree of accuracy based on a knowledge of the analyte structure. A number of schemes have been proposed.32-38 Usually, approaches to prediction of retention time assume that the hydrophobicity of a complex molecule can be divided into contributions of hydrophobicity or hydrophilicity of each functional group comprising it. For example, the retention of a peptide may be estimated by adding up the retention times of the amino acids...

References

M., Scimedia Mass Spectrometry Ionization Methods, accessed 3 9 2000, 2. Niessen, W.M.A., Advances in instrumentation in liquid chromatography-mass spectrometry and related liquid-introduction techniques, J. Chromatogr. A, 794, 407, 1998. 3. Sakairi, M. and Kato, Y., Multi-atmospheric pressure ionization interface for liquid chromatography-mass spectrometry, J. Chromatogr. A. 794, 391, 1998. 4. Klink, F., New Sample Preparation Approaches for Biological Matrices for LC-MS, LCGC,...