Sugars HPLC analysis

A classic HPLC analysis of sugars is made by means of an isocratic elution with R1 detection hence the only degree of freedom is the choice of the column on which the level of separation depends. More recent issues that do not allow the use of isocratic elution are the use of an ELS detector or an electrochemical detector (ED). 

TABLE 19.3 Sensitivity of HPLC Analysis of Main Food Sugars and Related... 

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... 

The second half of the 1990s saw an increase in the use of dialysis (as a liquid-liquid extraction procedure). Its main advantage is the possibility of operating in an automatic mode by coupling a dialysis unit with an automatic injector, as demonstrated not only in HPLC analysis (17) but also in flow-injection determinations of reducing sugars in wines (18) and alcoholic fermentation broths (19). 

RF McFeeters. Single injection HPLC analysis of acids, sugars, and alcohols in wine. Abstract of papers of the American Chemical Society, (22 August 1993), 206(1) 51, 1993. 

The solubility of NHDC in hot water, alcohol, aqueous alkali, acetonitrile, dimethyl sulfoxide, and alcohol/water mixture facilitates its selective extraction from food samples (20,91,94). It is extracted from jams, fruit juices, and dairy products with methanol (66,93) or acetone (95) and filtered or centrifuged. Chewing gum samples are dissolved in chloroform and extracted with water. The extract is centrifuged, and the clear supernatant is injected into the HPLC (95). If necessary, sample cleanup and concentration may be achieved by selective adsorption or desorption (20) on Sep-Pak Cl8 (96). Tomas-Barberan et al. (93) used Amberlite XAD-2 resin for purification of jam extract. Sugars, pectin, and other polar compounds were eluted with water, and NHDC was eluted with methanol. After concentration, the extract was further purified on a Sephadex LH-20 column prior to HPLC analysis. 

When samples contain high quantities of interfering material (e.g., sugars, colloids), a sample-cleanup procedure is recommended. A sample preparation with solid-phase extraction cartridges (C18) was found to be quite useful and effective (180,193). Prior to HPLC analysis, all samples should be filtered through a 0.45-/zm or smaller membrane filter. 

FIGURE 1-9. Journal references to HPLC analysis of food and sugar, 1969-1988. (Adapted from reference 14 with permission.)... 

While there are several methods available for the HPLC analysis of cocaine [7], these appear to have been principally nsed in toxicological studies. For street drug analysis, the preferred method is cnrrently GC (either GC-FID or GC-MS). In addition to identification, GC-MS can also be nsed to quantify cocaine in street samples. For simple mixtures which contain only cocaine and a sugar, UV spectroscopy can also be employed for qnantification pnrposes. Examples of each of these approaches are detailed below. 

Figure 1.8 Chromatogram relative to HPLC analysis of sugars in a grape must sample. Analytical conditions column Aminex HPX-87H (300 x 7.8mm, 9p.m) (Bio-Rad Laboratories, Richmond, CA) at 60°C detector refractometer sample volume injected 20p,L solvent H2S04 0.013 N with isocratic elution at flow rate 0.6 mL/min...

Figure 7.1. HPLC analysis of carbohydrates (simple sugars) in soft drink using resin column and refractive index detection. HPLC conditions column BioRad Aminex HPX-87C (300 x 7.8mmi.d.) injection volume 10 pL mobile phase water, flow rate 0.6mL/min at 85°C detection refractive index. Chromatogram courtesy of PerkinElmer, Inc.

PAMAM scaffolds have been decorated with carbohydrates via oxime ligation [177], RAFT scaffolds have been functionalized with D-mannose, /V-acetylga-lactosamine and lactose via the reversed oxime ligation, i.e. the sugar molecules were aminoxylated (cf. Scheme 1) and then reacted in aqueous acetic acid with the RAFT scaffold provided on solid support and presenting four glyoxaldehyde functions. Excess sugar was recovered and RP-HPLC analysis of a reaction sample, cleaved from the resin, showed only the expected product [72],... 

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