Xanthan assay

In addition to the total carbohydrate assay for xanthan using the Dubois method, there are specific analytical methods that may be applied to determine how much of a specific group is present. For example, specific micromethods were applied by Nisbet et al (1982) to assay for 0-acetyl groups, pyruvate ketals and uronic acids. Further discussion of such methods is beyond the scope of this work. 

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LAI E P C, FARFARA A, VANDERNOOT V A, KONO M and POLSKY B (1998), Surface plasmon resonance sensors using molecularly imprinted polymers for sorbent assay theophylline, caffeine and xanthan , Can J Chem, 76, 265. 

Acid chloride handles on various templates 49-51 were acylated with equimolar mixtures of 19 different appropriately protected amines to prepare non-peptidic polyamide libraries. The three templates possess different types of symmetry and offer varying degrees of 3D spatial diversity. Screening for trypsin inhibition employing a chromogenic assay identified the xanthane analog 52 (K, = 9.4 pM) as a moderately active, but structurally novel, inhibitor of trypsin (see Fig. 7) [37]. 

Assay A sample yields, on the dried basis, not less than 4.2% and not more than 5.4% of carbon dioxide (CO2), corresponding to between 91.0% and 117.0% of Xanthan Gum. Isopropyl Alcohol Not more than 0.075%. 

C, com starch W, water S, sucrose X, xanthan gum G, guar gum A, alginate. Standard error (SE) between parentheses. Assays were performed in quintuplicate. Within a column, values with different superscripts are significantly different (P <. 05). 

Vitamin activity in foods and food products serves as an example where typical problems arise with traditional liquid solvent extraction and then where SFE has been used to address these concerns [30]. In addition to the routine assay of food products, there is a considerable amount of research being conducted on the role of carotenoids and xanthans as antioxidants in the human body. This antioxidant-role may address many health concerns such as aging and various diseases. The "friendly-extracting-environment" of SFE has some merit of consideration for such studies, particularly with regard to the lesser possibility of oxidation of the analytes during the sample preparation step. 

Methods of analysis. The total protein concentration of crude solutions, including cellular proteins, was determin by the biuret method (72). With dilute xanthan solutions, this method was not sensitive enough, and a spectrofluorometric assay was carried out. This method consisted of an acid hydrolysis of the samples followed by derivatization with o-phthaldialdehyde and HPLC analysis on a Cl8 reverse column of the amino acids released, using spectrofiuorescence as the detection nKxie. 

An additional filtration step was required for some xanthan solutions to remove other particulates, such as undissolved clumps of the powdered xanthan. A 0.22 /zm or 0.45 jum filter usually removed this debris. The xanthan concentration was measured by the phenol-sulfuric acid colorimetric assay for carbohydrates. Solution viscosities were determined using a coni-cylindrical (cup-and-bob) rotational viscometer. 

It is very important in a laboratory flood or in analysing fluids in the field to have an accurate and reproducible method for detecting and assaying polymers. There are certain methods that can be used that are common to both polymers, such as radiolabelling (Szabo, 1975 Sorbie et al, 1987d) and total organic carbon (TOC) assays. However, the most common methods of assay for xanthan and HPAM use the particular chemistry of the molecules involved. In the following sections the chemical methods of analysis that have been used to detect xanthan and polyacrylamide are described. The use... 

These different mechanisms were reviewed some time ago by Willhite and Dominguez (1977), and each is illustrated schematically in Figure 5.1. Before discussing these mechanisms here, it should be pointed out that the experimental measurement of polymer retention, by all mechanisms, depends on the ability to determine accurately the polymer concentration. Ultimately, all such measurements involve a material balance estimate. The issues involved in assaying polymer concentration are discussed in some detail, for both HPAM and xanthan, in Section 2.4. 

Properties Creamy-wh. gran, powd. 90% min. through 20 mesh. 5% max. through 200 mesh almost neutral odor sol. in cold water vise. 1200-1600 mPa-s pH 6-8 (1%) 91-108% assay 8-14% loss on drying Storage 2 yr. shelf life when stored cool and dry GRINDSTED Xanthan SM [Danisco Textural Ingredients]... 

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