Quantitative HPLC method for

A qualitative and quantitative HPLC method for analysis of mixtures of 12 antioxidants was described Grosset et al. (121). For the identification of the components present, gradient elution with a convex profile from 35 65 water-methanol to pure methanol is used, on a Waters 5-/xm C18 column, with UV detector. Propyl gallate was not separated by this system. For quantitative analysis, with UV and electrochemical detectors in series, the water-methanol mixture or pure methanol was used as the eluent, under isocratic conditions, with lithium perchlorate as supporting electrolyte. An applied potential ranging from +0.8 to +1.7 V allows detection of all the antioxidants tested. Both modes of detection were very sensitive, with limits of detection as low as 61 pg. 

A quantitative HPLC method for the analysis of sphingolipids as their perbenzoyl derivatives was first developed for ceramides (5). Ceramides can be conveniently derivatized with benzoic anhydride in pyridine (3 hrs at 110°C) and the products formed have been utilized for the quantitative analysis of NFA and HFA ceramides in normal and Farber s disease tissue. Iwamori and Moser also utilized this procedure for the analysis of ceramides in Farber s disease urine (6). More recently Iwamori and Moser (7) established that the ceramide derivatives formed by reaction with benzoyl chloride or benzoic anhydride are analogous to those formed with cerebrosides. They also characterized the behavior... 

Bergeron, C., Livesey, J., Awang, D., Arnason, J., Rana, J., Baum, B., and Letchamo, W. 2000. A quantitative HPLC method for the quality assurance of Echinacea products on the North American market. Phytochem. Anal. 11, 207 -215. 

Bohman and colleagues described a reverse-phase HPLC method for the quantitative analysis of vitamin A in food using the method of standard additions. In a typical example, a 10.067-g sample of cereal is placed in a 250-mL Erlenmeyer flask along with 1 g of sodium ascorbate,... 

With the development of HPLC, a new dimension was added to the tools available for the study of natural products. HPLC is ideally suited to the analysis of non-volatile, sensitive compounds frequently found in biological systems. Unlike other available separation techniques such as TLC and electrophoresis, HPLC methods provide both qualitative and quantitative data and can be easily automated. The basis for the HPLC method for the PSP toxins was established in the late 1970 s when Buckley et al. (2) reported the post-column derivatization of the PSP toxins based on an alkaline oxidation reaction described by Bates and Rapoport (3). Based on this foundation, a series of investigations were conducted to develop a rapid, efficient HPLC method to detect the multiple toxins involved in PSP. Originally, a variety of silica-based, bonded stationary phases were utilized with a low-pressure post-column reaction system (PCRS) (4,5), Later, with improvements in toxin separation mechanisms and the utilization of a high efficiency PCRS, a... 

Homero-Mendez, D., Gandul-Rojas, B., and Mmguez-Mosquera, M.L, Routine and sensitive SPE-HPLC method for quantitative determination of pheophytin a and pyropheophytin a in olive oil. Food Int., 38, 1067, 2005. 

Discuss qualitative and quantitative analysis methods for HPLC and how they are different from those of GC. 

HPLC has more or less supplanted GC as a method for quantifying drugs in pharmaceutical preparations. Many of the literature references to quantitative GC assays are thus old and the precision which is reported in these papers is difficult to evaluate based on the measurement of peak heights or manual integration. It is more difficult to achieve good precision in GC analysis than in HPLC analysis and the main sources of imprecision are the mode of sample introduction, which is best controlled by an autosampler, and the small volume of sample injected. However, it is possible to achieve levels of precision similar to those achieved using HPLC methods. For certain compounds that lack chromophores, which are required for detection in commonly used HPLC methods, quantitative GC may be the method of choice, for analysis of many amino acids, fatty acids, and sugars. There are a number... 

This chapter does not constitute a comprehensive review of all recently published HPLC methods for the analysis of water-soluble vitamins. It is a summary of selected methods and is intended to serve as a tool for the analyst in search of a method for quantitating one or more of the water-soluble vitamins in foods. The selected methods must ... 

Table 1 HPLC Methods for Quantitating Total Vitamin C in Foods (C,8 Columns Fluorescence Detection)... 

Table 2 HPLC Methods for Quantitating C Vitamers in Foods (C18 Columns UV Absorbance Detection)... 

Three recent reviews specifically cover HPLC methods for quantitating riboflavin in foods. In addition to HPLC methods, Nielsen (81) summarized paper chromatography, TLC, and open-column chromatography procedures for quantitating total riboflavin and the individual vitamers in foods, pharmaceuticals, and biological samples. Russell (44) included a brief discussion of the standard methods, along with HPLC and flow injection analyses published between 1990 and 1994 for total riboflavin and the individual vitamers in foods. Ball (45) reviewed HPLC methods for quantitation of riboflavin, as well as chemical and microbiological riboflavin assays for foods. 

Although microbiological methods are widely used for quantitation of total niacin, they tend to be time consuming and labor intensive (100). Reproducibility problems have also been reported (96). The HPLC methods for foods generally determine total niacin rather than the individual vitamers. Table 14 summarizes a recent HPLC method for quantitating total niacin in foods. The simultaneous determination of niacin with one or more other B vitamins is covered later in this chapter in Sec. XI. 

Three recent reviews included HPLC methods for food folacin. Mullin and Duch (122) reviewed selected HPLC methods for determining the folacin vitamers in foods, biological tissues, and pharmaceuticals. They also included paper chromatography, TLC, and microbiological methods. Russell (44) reviewed selected HPLC methods published between 1990 and 1994 for folacin quantitation in foods, including a brief review of the reference methods. Ball (45) reviewed HPLC and microbiological methods for the quantitation of folacin in food samples. 

The first HPLC methods for quantitating vitamin B12 in foods are beginning to appear (Tables 21 and 22). The detection problems are being addressed by coupling HPLC with other analytical techniques. Further work is needed for routine analysis of these vitamers by HPLC. 

Table 21 HPLC Methods for Quantitating B l2 Vitamers in Foods (C8 Columns Detection by Radioassay)... 

Table 22 HPLC Methods for Quantitating B12 Vitamers in Foods (C,g Columns Detection by Electrothermal Atomic Absorption)... 

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