Food analysis separation

Capillary electrophoresis is increasingly used in food analysis due to its separation performance combined with the short time of analysis. - CapiUary electrophoresis recently applied to colorant measurements includes technical variants such as capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography. ... 

Coupled LC-LC can separate high-boiling petroleum residues into groups of saturates, olefins, aromatics and polar compounds. However, the lack of a suitable mass-sensitive, universal detector in LC makes quantitation difficult SFC-SFC is more suitable for this purpose. Applications of multidimensional HPLC in food analysis are dominated by off-line techniques. MDHPLC has been exploited in trace component analysis (e.g. vitamin assays), in which an adequate separation for quantitation cannot be achieved on a single column [972]. LC-LC-GC-FID was used for the selective isolation of some key components among the irradiation-induced olefinic degradation products in food, e.g. dienes and trienes [946],... 

Capillary electrophoresis (CE) is a modem analytical technique that allows the rapid and efficient separation of sample components based on differences in their electrophoretic mobilities as they migrate or move through narrow bore capillary tubes (Frazier et al., 2000a). While widely accepted in the pharmaceutical industry, the uptake of CE by food analysts has been slow due to the lack of literature dedicated to its application in food analysis and the absence of well-validated analytical procedures applicable to a broad range of food products. 

Retinoids The challenge in fat-soluble vitamins analysis is to separate them from the lipid fraction that contains interferents. Alkaline hydrolysis, followed by LLE, is widely applied to remove triglycerides. This technique converts the vitamin A ester to all-trani-retinol. A milder process, which does not hydrolyze vitamin A ester, is alcoholysis carried out with metha-nolic KOH solution under specific conditions that favor alcoholysis rather than saponification. A more accurate explanation of this technique is reported in the book Food Analysis by FIPLC [409]. For some kind of matrices a simple liquid extraction can be sufficient with [421-423] or without [424,425] the purification... 

The first section of the book explores emerging novel aspects of HPLC and related separation methods based on the differential velocity of analytes in a liquid medium under the action of either an electric field (capillary electromigration techniques) or a gravitational field (field-flow fractionation). The section focusing on applications highlights four significant areas in which HPLC is successfully employed chiral pharmaceutical, environmental analysis, food analysis, and forensic science. 

The first edition of Food Analysis by HPLC fulfilled a need because no other book was available on all major topics of food compounds for the food analyst or engineer. In this second edition, completely revised chapters on amino acids, peptides, proteins, lipids, carbohydrates, vitamins, organic acids, organic bases, toxins, additives, antibacterials, pesticide residues, brewery products, nitrosamines, and anions and cations contain the most recent information on sample cleanup, derivatization, separation, and detection. New chapters have been added on alcohols, phenolic compounds, pigments, and residues of growth promoters. 

M. Careri and A. Mangia, Multidimensional detection methods for separations and their application in food analysis , Trends Anal. Chem. 15 538-550 (1996). 

It is with the topic of analyte determination in foods by the technique of analytical AAS that this chapter is concerned. Analyte quantitation (d above) by this technique is thus the main thrust of this treatment, but of necessity, the intimately related procedures of sample treatment (b) and analyte separation and manipulation (c) will also be discussed insofar as they bear on quantitative measurement by AAS. Food for human consumption is the main concern of this chapter. Peripheral discussion, however, of allied commodities such as plants and animal feedstuffs, is included to make the treatment more comprehensive, especially in areas where there is a dearth of publications relating to food-analysis applications of atomic spectrometry. For detailed accounts of methodologies bearing on such related materials, the reader is referred to the other chapters in this volume. 

There are examples in the literature for the application of LC-MS-NMR in the pharmaceutical industry. In the area of natural products, this technique has been applied as a rapid screening method of searching unknown marine natural products in chromatographic fractions [108] and for the separation and characterization of natural products from plant origin [109, 110]. Another application is in the area of combinatorial chemistry [111]. In the field of drug metabolism, LC-MS-NMR has been extensively applied for the identification of metabolites [112-120]. And finally, LC-MS-NMR has been used for areas such pharmaceutical research [35,121,122], drug discovery [123], degradation products [101], and food analysis [124,125]. 

The example of an LC chiral separation shown in Figure 12.6 serves to emphasise (a) that the demand for effective chiral selectors is such that even complex synthetic chiral selectors have been commercialised, and (b) the interest in chirality extends beyond pharmaceutical applications, being widespread and in this instance being found in food analysis. Aspartame (N-DL-cx-aspartyl-DL-phenylalanine methyl ester (Figure 12.7)) can exist as four stereoisomers, DD-, LL-, DL- and LD-. On an achiral column DD- and LL- would appear as a single peak which would be separable from another single peak arising from DL- and LD-. A chiral column is needed to separate the enantiomeric pairs (i.e. DD- from LL- and DL-from LD-). The LL-isomer is used as artificial sweetener (under the brand... 

MI-SPE has been applied in either on-line or off-line mode for several analytes. In the first case, MIP is packed as an HPLC precolumn. Column switching and pulsed elution modes are employed in on-line MI-SPE. One advantage of this design is the automation capability and the direct coupling to HPLC or other separation modes. Despite these advantages, the off-line mode, which has been successfully applied to bio and environmental and food analysis, is the most commonly practiced method. 

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